Biomedical subjects

R C Hermida

Publications and source records attributed to R C Hermida.

At least 73 records · Page 4Linked to original sources

PubMed1990

Circannual rhythm of plasma growth hormone in girls (but not boys) with constitutional short stature.

GH concentrations (in ng/ml) were determined by radioimmunoassay in plasma obtained at about 3-hour intervals during a 24-hr sampling span from 40 boys and 14 girls of short stature, 6-14 years of age, living on a diurnal waking (approximately 07:00 to approximately 22:00), nocturnal resting routine. Circadian rhythm parameters were first computed by the single and population mean cosinor fits of a 24-hour cosine curve. Circadian parameter comparisons revealed an intergroup difference between the genders in A (P = .012) and, perhaps, in M (P = .078), but not in 0 (P = .957). In the search for circannual variability, individual circadian Ms were fitted by LLS with a 1 year cosine curve. The LLS harmonic analysis shows a circannual rhythm for the girls (P = .037; M = 8.54; A = 5.38; 0 = -214 degrees from January 1), but not for the boys. Moreover, a 3.5 months prominent component was also found for both the individual circadian Ms (P = .010) and As (P = .012) when all subjects are considered for analysis irrespectively of gender. These infradian characteristics complement circadian differences in GH between boys and girls and must be taken into account in the development of any protocol for studies of GH responses to GH-releasing hormone in children with short stature.

Adolescent↗

PubMed1990

Similar circadian characteristics of serum glucose in boys and girls of short stature.

In the absence of any gastroenterologic complaint, circadian variations characterize serum GL in 22 boys and 7 girls of short stature, 6-14 years of age, living on a diurnal waking (approximately 07:00 to approximately 22:00), nocturnal resting routine, consuming the usual hospital diet. Blood was drawn at about 3-hour intervals during a 24-hour sampling span and serum stored frozen at -60 degrees C until radioimmunoassay for GL concentration (in mg/dl). Circadian rhythm parameters were computed by the single and population mean cosinor fits of a 24-hour cosine curve. A parameter-comparison of data from the two genders indicates similar circadian M, A and 0 for both groups. The Ps for a comparison of Ms, As, 0s and (A,0) pairs are .635, .183, .385 and .308, respectively. The larger differences between genders were found for the circadian A. In human beings, differences in the A of a rhythm are associated with differences in the probable development of several civilization diseases. In this sense, evaluation of risk by appropriately designed questionnaires should next complement blood sampling in groups of children differing in age, gender, health or ethnicity, with the purpose in mind of deriving prediction regions for assessment of health, risk or disease.

Adolescent↗

PubMed1990

Infradian characteristics of plasma cortisol in children of short stature.

CT concentrations (in micrograms/dl) were determined by radioimmunoassay in plasma obtained at about 3-hour intervals during a 24-hour sampling span from 42 boys and 16 girls of short stature, 6-14 years of age, living on a diurnal waking (approximately 07:00 to approximately 22:00), nocturnal resting routine. Circadian rhythm parameters were first computed by the single and population mean cosinor fits of a 24-hour cosine curve. A parameter-comparison shows similar circadian rhythm parameters for both genders, the Ps for a comparison of Ms, As, 0s and (A,0) pairs being .69, .14, .73 and .32, respectively. In the search for infradian variability, individual circadian Ms were first fitted by LLS. The LLS harmonic analysis shows prominent components with periods of 8, 7, 4, 3 and 1 months, with ordering P-values of .031, .011, .009, .018 and .024, respectively. The rhythm parameters thus obtained were used as initial values for the NLLS method. This approach only detects the circaseptrigintan (7 months) component, with estimated period, M, A and 0 of 5023.96 hours, 10.32 micrograms/dl, 3.34 micrograms/dl and -273 degrees, respectively. These not anticipated infradian characteristics of the adrenal cortisol cycle may constitute quantitative parameters in dealing with risk in health and may serve to monitor any possible progression of a condition into a disease.

Adolescent↗

PubMed1990

Chronoendocrine assessment of the risk of developing depressive disorders.

Chronoepidemiology studies alterations of biologic rhythms with several frequencies as harbingers and possibly determinants of the risk of developing certain diseases. Along these lines, a method for pattern discrimination, the so-called "monotest", involving the leave-one-out technique for the estimation of the PM, is here used in the search for classifiers of personality. By this method, chronoendocrine relations of a DPP are explored in 12 plasma hormones sampled around the clock in 4 seasons on a small number of clinically and psychologically healthy women, 29-36 years of age. Subjects were separated in two groups by scores for DPP of the Mini-Mult, an abbreviated version of the Minnesota Multiphasic Personality Inventory. Discriminant analysis singles out plasma aldosterone as the primary classifier for DPP in winter. In spring, the best classifiers include 17-OH progesterone and insulin, whereas in the summer the circadian amplitude of 17-OH progesterone classifies best. Finally, the identified classifiers in the fall are DHEA-S, estradiol and estrone. In clinical health, hormones are thus sensitive in ordering people who, according to questionnaires, are at different risk of developing emotional disorders. Results also illustrate the need to consider the intermodulation of circadian and circannual rhythms, whenever endocrine variables are being determined in human plasma.

Adult↗

PubMed1990

Infradian variation in the incidence of giardiasis assessed by linear-nonlinear rhythmometry.

The analysis of biological time series necessarily involves mathematical and physiologic techniques for purposes of data collection and interpretation, respectively. To assess a biologic rhythm in a given time series, one can first fit a cosine curve with a fixed period to the data by LLS. When the period is unknown or when there is more than one significant period, with no integral relation among them, LLS have to be replaced by NLLS. In applying the NLLS method, initial values for all the parameters in the model are first estimated by LLS. These are usually the overall M and the periods, As and 0s corresponding to each component found to be statistically significant by LLS. This combined approach was used in the search for infradian variability in the incidence of GD, the most common gastrointestinal parasitic disease in the USA at the present time. Monthly totals in ten consecutive years (1977 to 1986) of cases of GD detected in Minnesota (USA) were first fitted by LLS. The linear harmonic analysis shows the anticipated 1-year synchronized circannual rhythm with a period of 8766 hours (P less than .001) and other prominent components with periods of 7 (P = .038), 6 (P = .003), 5 (P = .001) and 3 (P less than .001) years, which were not anticipated. The rhythm parameters thus obtained are then used as initial values for the nonlinear method. Components of 5, 3. and 1 years are then detected by the NLLS approach, that also gives estimates and 95% confidence intervals for the period, the M, the A, and the 0 of each significant component. Of very great interest are infradian changes also seen time-macroscopically in other data on numbers of waterborne cases and outbreaks of GD. Awareness of the thus detected predictable variability in the incidence of GD with frequencies lower than a year may be important in the diagnosis and treatment of this infectious disorder.

Biometry↗

PubMed1990

Differences in circannual characteristics of the incidences of amebiasis and giardiasis.

Entamoeba histolytica is the most common pathogenic intestinal parasite in México. Prevalence rates of AM vary widely from place to place, being higher in areas with poor sanitation, households and institutions, and among male homosexuals. Early recognition and treatment may be necessary to prevent its spread in the community. Intervention by preventive health education is indicated. The timing of such educational endeavours may be adjusted to any rhythmic and to that extent predictable changes in the incidence of AM and of any other possibly related gastrointestinal parasitic disease, such as GD. Accordingly, monthly totals of cases of AM and GD detected in Monterrey, (México) between November, 1985, and October, 1987, were fitted by linear least-squares with a 1-year cosine curve. The no-circannual rhythm assumption in the incidence of AM and GD was rejected in both cases (P = .006 and .049, respectively). A comparison of circannual parameters shows differences in M, A and phi between the incidences of AM and GD, the Ps for those comparisons being less than .001, .014 and .041, respectively. A high incidence of GD (above the yearly mean) consistently observed in April could be, however, related to the circannual pattern of AM, showing higher incidences in the spring. The timing of any preventive intervention should take into consideration the circannual variability in the incidence of AM and the differences or correlations with the circannual patterns of other gastrointestinal parasitic diseases.

Entamoebiasis↗

PubMed1989

Circadian and ultradian characteristics of plasma growth hormone in children with normal and short stature.

Circadian and ultradian variations characterize plasma growth hormone (GH) in 40 boys and 10 girls of short stature, and 15 boys and girls of normal stature, 6-14 yr of age, living on a diurnal waking (approximately 07:00 to approximately 22.00), nocturnal resting routine. Blood was drawn at about 3-h intervals during a 24-h span and serum stored frozen at -60 degrees C until radioimmunoassay for GH concentration. A linear least-squares spectrum analysis of those data reveals the anticipated statistically significant circadian rhythm as the principal spectral feature for all groups. Prominent components with a period of 12 h were also found for the groups of short boys and short girls, and of 8 h for short boys. A parameter comparison indicates similar circadian characteristics between short and normal children, whether one compares boys (p = .52, .30 and .84 for comparison of rhythm-adjusted means (M), amplituedes (A) and acrophases (phi), respectively), girls (p = .65, .37 and .92), or all children (p = .53, .31 and .87). These results notwithstanding, studies of GH responses to GH-releasing hormone in children with short stature and healthy controls should be extended to evaluate any possible difference in terms of gender and circadian or ultradian timing.

Adolescent↗

PubMed1987

Bootstrapped potential circadian harbingers if not determinants of cardiovascular risk.

Among 12 endocrine variables in blood from clinically healthy adult women sampled systematically around the clock and the year, discriminant analysis methods have singled out certain hormones in certain seasons as classifiers for a high or low risk of developing diseases associated with a high circadian rhythm-adjusted mean (midline estimating statistic of rhythm, MESOR, M) of blood pressure, i.e., risk of M-hypertension (RMH). Before extending the labor intensive, costly data base, showing circadian changes with RMH, we reanalyzed available data by circadian bootstrapping, complementing earlier circannual bootstrapping. Differences in circadian M for aldosterone in all four seasons and for TSH in spring and summer (the only seasons checked), but not for the cortisol M checked in spring and summer, are validated, as are differences in circadian amplitude for TSH in spring and summer and aldosterone in spring. Identification of classifiers provides cost-effective, time-specified endocrine checks complementing the targeted automatic monitoring of blood pressure as part of a system of chronobioengineering for health maintenance.

Adolescent↗

PubMed1987

Ultradian rhythmometry by adaptive line enhancer.

Widrow's adaptive line enhancer (ALE) was applied to human rectal temperatures at 12-min intervals for 9 days. Changes along the scale of 9 days in circadian pattern suggested the occurrence of infradian variation, resolved by analyses of the entire series by linear-nonlinear rhythmometry. Once the original signal is filtered to extract the circadian component, ultradian components appear. A wide peak with a period of about 100 min, seen each day, may reflect a consistent ultradian component. Other peaks at lower ultradian frequencies (around a period of approximately 8 hr) are unsteady and may correspond to harmonics of the partially extracted circadian oscillation. Ultradian components with periods of approximately 131 and approximately 68 min were also suggested independently by population-mean cosinor summarizing data collected over a total of 158 days. Results show the ability of ALE to detect and reconstruct periodic components in noise and to track their changes in frequency, notably when other methods are also used to assess separately the components and the corresponding uncertainties involved.

Biometry↗

PubMedDate not supplied

Time-qualified reference values for 24 h ambulatory blood pressure monitoring.

BACKGROUND: The development of automatic instrumentation for ambulatory blood pressure monitoring makes it possible to follow the time-course of blood pressure variation over 24h or more in large groups of individuals. Whenever samples from a reference group of individuals are available, one may construct a prediction interval that is expected to include any single future observation from the reference population, with a specified confidence. Alternatively, the reference interval may consist of a tolerance interval that will include at least a specified proportion of the population with a stated confidence. OBJECTIVE: To examine prospectively whether a new, combined tolerance-hyperbaric test approach of establishing tolerance intervals for the circadian variability of blood pressure as a function of gestational age and then computing the hyperbaric index as a measure of blood pressure excess provides high sensitivity and specificity in the early identification of pregnant women who subsequently will develop gestational hypertension or pre-eclampsia. METHODS: We used data sampled for 48 h from 148 normotensive men and women to compute and compare time-specified tolerance and prediction intervals for blood pressure. Once the threshold, given by the upper limit of the tolerance interval, was available, the hyperbaric index, as a measure of blood pressure excess, could be calculated by numerical integration as the total area of any given patient

Blood Pressure Monitoring, Ambulatory↗

PubMedDate not supplied

Circadian distribution of hematology variables in subjects with multiple sclerosis.

Hematology variables were measured in blood samples obtained every 3h (8/24h) from 10 multiple sclerosis (MS) patients and 34 healthy subjects and analyzed for circadian characteristics using the population multiple-components method. Red blood cell (RBC) and hemoglobin levels as well as hematocrits exhibited circadian rhythms with minimal amplitudes in healthy individuals and insignificant variability in the smaller group of MS patients. In contrast the total white blood cell (WBC) and platelet counts for MS patients and healthy individuals both showed significant circadian characteristics while the mean 24h WBC and platelet levels did not significantly differ between the two groups. When the different WBC subsets were examined independently, statistically significant circadian rhythms were seen for lymphocytes and eosinophils for both MS patients and healthy individuals and for neutrophils only in the latter. Moreover, the 24h mean levels of lymphocytes, basophils, and eosinophils were significantly higher for the healthy controls while those of monocytes were higher for the MS patients. However, of all the variables tested with significant circadian rhythms in both groups of individuals, only those of lymphocyte numbers exhibited different patterns with somewhat higher amplitude in healthy individuals and a peak level occurring over an hour after that of MS patients. These changes may be the reflection of a disturbance in the regulation of patterns of lymphocyte activity and migration in MS patients. In addition, the elevation in circulating monocytes in MS patients is consistent with the inflammatory nature of the disease.

Adult↗

PubMedDate not supplied

Chronotherapy of ovarian cancer: effect on blood variables and serum cytokines. A case report.

A 7-year-old patient with Stage III-c ovarian cancer was subjected to 8 cycles, approximately four weeks apart, of chronobiologically-optimized treatments with combination of three anti-cancer agents: Four cycles at AM, Cytoxan and PM, cis-Platinum; four cycles at AM, Adriamycin and PM, cis-Platinum. A second look laporoscopy revealed clean intestines, no definite masses in the pelvis area although there was an apparent mass in the right upper pelvis and several slightly enlarged lymph nodes in the base of mesentery. Six cycles of Taxol were administered at about Noon. Seven months remission appeared evident as judged by no changes in monthly examinations, in blood work or in CA-125 marker levels which remained below 12 U/ml. During the eight month the CA-125 marker began to rise, 36 then to 52 U/ml. A second 6 cycle series of Taxol was initiated but the CA-125 marker continued to rise, 57, 65, 72, 86, and 87 U/ml level. The patient declined in spirit, in well-being and expired 2 weeks later, 31 months after the initial diagnosis of cancer. Blood hematology, chemistry, and cytokines variables were analyzed at about weekly intervals. Significant reductions in total WBC, neutrophiles and platelet levels were evident during the second week of all cycle treatments, while increases were noted in serum levels of IL-2, IL-6 and IL-10 following Cytoxan-cis-Platinum-Adriamycin, but not Taxol. After each infusion moderate and temporary increases in RBC levels were noted. The treatments impact on hematology, chemistry, cytokine variables and on the integrity of the patient, are presented and briefly discussed.

Aged↗

PubMedDate not supplied

Human mesor-hypertensive chronorisk.

Twelve endocrine variables in blood from a small number of clinically healthy adult women were sampled systematically around the clock and the seasons. Pattern discrimination methods singled out certain hormone values in certain seasons as classifiers for a high vs low risk of developing diseases associated with a high blood pressure. Further evidence in support of such classifiers is obtained on data from adolescent, menstrually cycling young adults and post-menopausal women, here analyzed as pool of series, with the scope of the data from any one age group greatly extended by a resampling procedure, namely, by bootstrapping. This mathematical approach was carried out on data series around the clock and seasons on several hormones as well as systolic and diastolic blood pressure. Classifier roles were strongly supported for plasma aldosterone and thyroid stimulating hormone, originally by an analysis of variance and, in the case of aldosterone, by circannual cosinor analysis and by numerical resampling. Circannual bootstrapping, a procedure recommended for broad routine use as a safeguard for hypothesis testing, was also done for plasma cortisol, dehydro-epi-androsterone sulfate and prolactin, variables for which (parametric) analyses of variance and cosinors did not reveal any difference between groups at high and low cardiovascular risk. In these instances, bootstrapping results are tentative and await further analyses. Results show the ability of circannual bootstrapping to detect outliers. Identification of classifiers provides cost-effective endocrine checks complementing the targeted automatic monitoring of blood pressure. Circannual indices for risk evaluation are, however, costly in several ways since it takes at least a year and quite a few samples to estimate them reliably. Accordingly, we also extended the scope of previous results by the application of an added procedure for circadian bootstrapping. With circadian as well as circannual bootstrapping, we here illustrate a major potential component of a system of chrono-engineering for health maintenance. This system should start with focus on the newborn. The results on adults here analyzed are likely to be more prominent in the neonate, to the extent that they are genetic in origin, yet amenable to modification by the extra-uterine environment.

Adolescent↗

PubMedDate not supplied

Circannual bootstrapping complements pattern discrimination in the assessment of endocrine markers for an expansive personality (EP).

The bootstrap distribution of the difference in the circannual mesor of DHEA-S, TSH and LH between healthy adult women of a lowly or highly expansive personality, assessed by scale 9 of an abbreviated Minnesota Multiphasic Personality Inventory, validates the potential classifying role of these hormones, originally singled out by methods of pattern discrimination.

Adult↗

PubMedDate not supplied

Chronobiologic pattern discrimination of plasma hormones, notably DHEA-S and TSH, classifies an expansive personality.

Methods of chronobiologic pattern discrimination, a "monotest' involving the leave-one-out technique and a "maximin distance' algorithm for cluster analysis, along with stepwise discriminant analysis procedures and correlation techniques are used in the search for classifiers of personality. By these methods, chronoendocrine relations of an expansive personality are explored in data sampled around the clock in 4 seasons on 10 North American and 3 Japanese women. Of 12 plasma hormones determined in each season, DHEA-S shows a time-dependent relation to an expansive, egocentric personality assessed by an abbreviated version of the Minnesota Multiphasic Personality Inventory; time-dependent co-classifiers are TSH, LH, prolactin and cortisol. Cost-effective recommendations for sampling are thus proposed for further tests of endocrine factors classifying for an expansive personality and, perhaps, classifying also for any associated vulnerability or risk state.

Adolescent↗

PubMedDate not supplied

Bootstrapping and added data discriminate, at low blood pressures, neuroendocrine risk of developing mesor-hypertension.

Under room-restricted conditions in a clinical research center, blood pressure and circulating aldosterone and TSH, sampled along 24-h and seasonal scales, reveal differences between small groups of young adult clinically healthy women at high or low risk of developing a high blood pressure. In view of the small sample sizes, data on additional age groups were added and both the original and the extended samples were further analyzed by bootstrapping. Monte Carlo procedures thus applied support the validity of the rhythm-stage-dependent endocrine and blood pressure differences as a function of the risk of developing a high blood pressure.

Aldosterone↗

PubMedDate not supplied

Time-dependent effects of ASA administration on blood pressure in healthy subjects.

Several studies aimed at testing the effects of low-dose acetylsalicylic acid treatment (ASA, aspirin) in the prevention of preeclampsia conclude that beneficial effects of such treatment outweigh adverse ones. Since recent results suggest that desired effects upon lipoperoxides and beta-adrenergic receptors are dependent on the circadian timing of ASA administration, we aim to study if ASA therapy can be optimized by timing according to the rest-activity cycle. Accordingly, before conducting clinical trials on pregnant women, we have examined in clinically healthy subjects the possibility that effects of ASA upon blood pressure could indeed be time-dependent. We studied 55 healthy subjects (35 men and 20 women), 19-24 years of age (mean +/- SD: 20.9 +/- 1.8). Subjects were living on their usual diurnal waking (approximately 08:00 to approximately 24:00), nocturnal resting routine during sampling, following every-day life conditions without any restriction. The systolic, mean arterial and diastolic blood pressures and heart rates of each subject were automatically monitored every 30 min. for 48 hrs with an ABPM-630 Colin (Komaki, Japan) device before and after a one-week course of aspirin (500 mg/day). Subjects were randomly assigned to one of three groups, according to the circadian timing of administration of the daily dose of ASA: within two hours of awakening (R x 1), seven to nine hours after awakening (R x 2), or within two hours before bedtime (R x 3). The second blood pressure profile was obtained during the sixth and seventh days of treatment (to avoid differences in activity dependent on the day of the week). Results indicate a statistically significant blood pressure reduction (negative mean area between the blood pressure profiles obtained before and after aspirin administration) only when ASA was given seven to nine hours after awakening (R x 2; P = .012, .003, and .006 for systolic, mean arterial and diastolic blood pressure, respectively). These results were corroborated by a non-parametric (sign) test, also indicating the significant reduction in systolic and diastolic BP for R x 2 (P = .003 and .010, respectively). Non-invasive BP monitoring combined with the proper analysis of the time series thus obtained could then provide a cost-effective approach for testing the circadian optimization of long-term ASA administration for both cardiovascular disease prophylaxis and prevention of preeclampsia.

Adult↗

PubMedDate not supplied

Heart rate and blood pressure chronomes during and after pregnancy.

Whereas conventional time-unspecified single measurements of blood pressure and heart rate may mislead, influenced as they are, among other factors, by the individual's emotional state, position, diet and external stimuli generally, the chronobiologic evaluation of predictable variability in these physiologic variables assesses early cardiovascular disease risk in pregnancy by (a) the use of fully ambulatory devices and (b) the proper processing of the time series thus obtained. We have used this approach to quantify changes in 24-h synchronized circadian characteristics of cardiovascular variables in two consecutive pregnancies of a clinically healthy woman. The results were then compared with those obtained from data sampled after the second pregnancy. Blood pressure and heart rate were automatically monitored, at 1-h intervals, each time for at least 48 consecutive hours, and for a total of 76 days of monitoring in each pregnancy. Circadian parameters of those circulatory variables were computed for each 48-h profile of measurements by the least-squares fit of a 24-h cosine curve. Regression analysis of parameters thus obtained revealed patterns of variation of circadian rhythm-adjusted means and amplitudes with gestational age. In both pregnancies, the predictable variability of the circadian rhythm-adjusted mean of blood pressure can be approximated by a second-order polynomial model on gestational age: a steady linear decrease in systolic, mean arterial and diastolic blood pressures up to the 22nd week of pregnancy is followed by an increase up to the day of delivery. This pattern of variation is not found for data similarly sampled during non-pregnancy on the same woman. This longitudinal study confirms and extends to ambulatory everyday life conditions the predictable pregnancy-associated variability in blood pressure and heart rate and also allows the establishment of prediction and confidence limits for cardiovascular parameters in a healthy pregnancy.

Animals↗