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Biomedical subjects

T Fernandez

Publications and source records attributed to T Fernandez.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effect of acute pharmacological reduction of plasma free fatty acids on growth hormone (GH) releasing hormone-induced GH secretion in obese adults with and without hypopituitarism.

In obesity, there is a markedly decreased GH secretion. The diagnosis of GH deficiency (GHD) in adults is based on peak GH responses to stimulation tests. In the severely obese, peak GH levels after pharmacological stimulation are often in the range that is observed in hypopituitary patients. To distinguish obese subjects from GHD patients, it will be necessary to demonstrate that reduced GH responsiveness to a given test is reversible in the former, but not in the latter, group. Recent studies have shown that reduction of plasma free fatty acids (FFA) with acipimox in obese patients restores their somatotrope responsiveness. There are no data evaluating GH responsiveness to acipimox plus GHRH in obese adults with hypopituitarism. The aim of the present study was to evaluate the effect of acute pharmacological reduction of plasma FFA on GHRH-mediated GH secretion in obese normal subjects and obese adults with hypopituitarism. Eight obese patients with a body mass index of 34.2+/-1.2; eight obese adults with hypopituitarism, with a body mass index of 35.5+/-1.9; and six control subjects were studied. All the patients showed an impaired response to an insulin-tolerance test (0.15 U/kg, i.v.), with a peak GH secretion of less than 3 microg/L. Two tests were carried out. On one day, they were given GHRH (100 microg, i.v., 0 min), preceded by placebo; and blood samples were taken every 15 min for 60 min. On the second day, they were given GHRH (100 microg, i.v., 0 min), preceded by acipimox (250 mg, orally, at -270 min and -60 min); and blood samples were taken every 15 min for 60 min. The administration of acipimox induced a FFA reduction during the entire test. Normal control subjects had a mean peak (microg/L) of 23.8+/-4.8 after GHRH-induced GH secretion; previous acipimox administration increased GHRH-induced GH secretion, with a mean peak of 54.7+/-14.5. In obese patients, GHRH-induced GH secretion was markedly reduced, with a mean peak (microg/L) of 3.9+/-1; previous administration of acipimox markedly increased GHRH-mediated GH secretion, with a mean peak of 16.0+/-3.2 (P < 0.05). In obese adults with hypopituitarism, GHRH-induced GH secretion was markedly reduced, with a mean peak (microg/L) of 2+/-0.7; previous acipimox administration did not significantly modify GHRH-mediated GH secretion, with a mean peak of 3.3+/-1.1 (P < 0.05). The GH response of obese patients and obese adults with hypopituitarism was similar after GHRH alone. In contrast, the GH response after GHRH plus acipimox, was markedly decreased in obese adults with hypopituitarism (mean peak, 3.3+/-1.1), compared with obese patients (mean peak, 16.0+/-3.2) (P < 0.05) and control subjects (mean peak, 54.7+/-14.5) (P < 0.01). In conclusion, GH secretion, after GHRH-plus-acipimox administration, is reduced in obese adults with hypopituitarism patients, when compared with obese normal patients. Testing with GHRH plus acipimox is safe and is free from side effects and could be used for the diagnosis of GHD in adults.

Adult↗
PubMed1995

Test-retest reliability of the sensory organization test in noninstitutionalized older adults.

The purpose of this study was to determine the 1-week test-retest reliability of the Sensory Organization Test (SOT), using computer-generated scores and loss of balance (LOB) episodes in noninstitutionalized older adults. The SOT was administered to each subject on two separate days 1 week apart in an out-patient clinic. A volunteer sample of 40 individuals who were at least 65 years of age participated in this study. The main outcome measures were computer-generated scores for the first trial and the average of the three trials in each of the six sensory conditions of the SOT; computer-generated composite score of the six conditions; LOB on the first trial and any of three trials in each condition. The intraclass correlation coefficients (ICC) for the SOT first trial data ranged from .15 in Condition 3 to 0.70 in Condition 5. The ICCs for the SOT average of three trials ranged from 0.26 in Condition 3 to 0.68 and 0.64 in Conditions 5 and 6. Percent agreement was 77% to 100% for LOB on the first trial, as well as LOB on any of three trials of Conditions 1 through 6. As the conditions became more difficult, an increasing number of subjects experienced LOB. Analysis revealed fair to good test-retest reliability for computer-generated scores and good reliability for LOB across some conditions of the SOT. A modification to the current scoring system is suggested which would improve the reliability of the computer-generated scores of the SOT.

Aged↗
PubMed1995

Screening for Barrett's esophagus by balloon cytology.

OBJECTIVE: to determine whether balloon cytology would allow a nonendoscopic diagnosis of Barrett's esophagus. METHODS: In 10 unselected patients with Barrett's esophagus, balloon cytology was performed with a Brandt esophageal cytology balloon catheter prior to endoscopy/esophageal biopsy. Specimens were cytologically evaluated for the presence of goblet cells and/or dysplasia. RESULTS: No patient had goblet cells or definitive columnar cell dysplasia. CONCLUSION: This technique with a commercially available balloon catheter does not allow for a nonendoscopic diagnosis of Barrett's esophagus.

Barrett Esophagus↗
PubMed1994

1-year stability and prediction of cardiovascular functioning at rest and during laboratory stressors in youth with family histories of essential hypertension.

Blood pressure (BP). heart rate, cardiac index, and total peripheral resistance index were measured at rest and in response to postural change, forehead cold stimulation, and a video game challenge in a sample of 128 White and 155 African-American normotensive youth with family histories of essential hypertension (EH). These measurements were readministered 1 year later (12.5 +/- 3.2 months). Moderate temporal stability was observed for all resting and absolute stress responses. Reliability estimates for reactivity change scores were lower, although some were within acceptable ranges. African-American youth exhibited greater BP and peripheral resistance index reactivity to forehead cold on both evaluations. After controlling for various anthropometric and demographic parameters and the pertinent previous year's resting cardiovascular (CV) parameter, mean video game systolic blood pressure (SBP) responses were predictive of resting SBP whereas absolute forehead cold and video game diastolic responses predicted resting diastolic blood pressure (DBP) 1 year later. Mean video game DBP responses were also predictive of resting peripheral resistance index after controlling for significant demographic and anthropometric measures. CV reactivity is discussed with regard to possible value in prediction of changes in resting BP and cardiac structure prior lo establishment of EH.

Journal Article↗
PubMed1993

Sex differences in EEG coherence in normal children.

The idea that sex differences in the execution of different mental tasks mean a different cerebral organization met contradictory results. Sex differences in brain electrical activity were reported by various authors. The EEG coherences show functional and anatomical interrelation, so they may reveal differences in brain organization. This paper tries to demonstrate how sex differences are manifested in EEG coherences, in 42 right-handed control children, 18 girls and 24 boys, aged 7.6 to 13.3. Since the effect of age is high on EEG measurements, regression against age was calculated and eliminated. The Z-transformed coherence values were compared by Student's t-test. The results obtained showed that girls had higher right intrahemispheric coherence values than boys in all bands. These sex differences were more numerous in the theta band. The interhemispheric differences were slight and girls had higher coherences in all bands except for the alpha band, where boys had higher interhemispheric coherence than girls. These results show slight but consistent differences in the functional organization of the right hemisphere by sex and reveal the necessity to elaborate separated EEG norms for boys and girls.

Adolescent↗
PubMed1992

Visual evoked potentials, attention and mnemonic abilities in children.

We analyzed the correlation between attention and mnemonic processes and different visual evoked potential (VEP) parameters. A group of 34 children between 9 and 13 years old was studied. VEPs were recorded in C3, C4, P3, P4, O1, O2, T5 and T6 with linked ear lobes as reference. Two different types of stimuli were used: flash and checkerboard pattern. The power of VEPs was calculated as the sum of the square amplitude values for different time epochs. Correlation coefficients between left and right homologous VEPs were also computed. A visual selective attention task divided into 5 items of increasing difficulty and the Sternberg paradigm were applied. The performance was automatically evaluated by the computer, giving the number of correct responses (NCR) and other measures of performance. Correlation coefficients between VEP parameters and the scores obtained in the performance of tasks were calculated. It was observed that power in P3, P4, T5, and T6 and the correlation coefficients between central, parietal and temporal VEPs were positively correlated with NCR of both tasks. However, power in O1 and O2 was negatively correlated with NCR.

Adolescent↗
PubMed1991

Subcellular localization of nerve growth factor receptors in identified cells of the rat nucleus basalis magnocellularis: an immunocytochemical study.

The subcellular location of nerve growth factor receptor in the ventromedial portion of rat globus pallidus was investigated with affinity-purified monoclonal 192-IgG following the unlabelled antibody peroxidase-antiperoxidase immunocytochemical procedure. At the light microscopic level, punctate immunoreaction product was observed in the perinuclear region and in the plasma membrane of large, probably cholinergic neurons. Examination in the electron microscope of these neurons confirmed that nerve growth factor receptor-stained cells were basal forebrain cholinergic neurons. Within these cells, immunostaining occurred in the Golgi apparatus, in multivesicular bodies and, occasionally, in rough endoplasmic reticulum cisternae and the nuclear envelope. Moreover, patches of immunoreactivity were observed associated with the outer surface of the plasma membrane of the soma and their proximal dendrites and also with the plasma membrane of distal dendrites showing scarcity of synaptic input. Positive immunostaining was never observed in synaptic clefts, but filled the space between the plasma membranes of immunoreactive neurons and those of thin glial processes in their vicinity. The location of membrane nerve growth factor receptor in close apposition to membranes of neighbouring astrocytes rather than near synaptic complexes, suggests that glial cells may be a physiological source of nerve growth factor.

Animals↗
PubMed1990

Nutritional intervention: a key to child survival.

In a collaborative relationship, researchers from the Cebu Institute of Medicine and from the United States have carried out a series of longitudinal studies of breast feeding and infant growth in a rural Philippine community. On the basis of our findings, we have conducted field experiments designed to have mothers improve their infants' diets using locally available food. Contingent reinforcement strategies were used successfully to get mothers to change their behavior and beliefs about infant feeding practices. The use of reinforcements resulted in improved diets and very high rates of continuation of participation in the field experiments. We believe that this is a highly productive and cost effective way to approach the problem of gaining cooperation and continued involvement in a nutrition intervention effort.

Attitude to Health↗
PubMed1987

Keratoplasty for complicated leucomas.

Fifty cases of complicated leucomata in which keratoplasty was done during the last two years, are analysed. Although complicated cases yield not so good optical result, the results are much improved by proper pre-operative, operative and post-operative management.

Corneal Diseases↗
PubMed1986

Hexokinase PII from Saccharomyces cerevisiae is regulated by changes in the cytosolic Mg2+-free ATP concentration.

Hexokinase PII is not inhibited by high Mg-ATP concentrations if the Mg2+-free ATP is kept at low levels (0.01 mM) in the assay mixture. Hexokinase PI activity is not affected either by Mg2+-free ATP nor by free Mg2+ in the assay mixture. Thus, hexokinase PI and PII activities appear not to be regulated by substrate inhibition as proposed previously [Kopetzki, E. & Entian, K. D. (1985) Eur. J. Biochem. 146, 657-662]. However, the level of Mg2+-free ATP in the hexokinase PII assay mixture strongly affects the enzyme activity by decreasing the Vmax and increasing the Km value for Mg-ATP from 0.15 mM to 5.0 mM. The physiological role of this inhibition, which has not been described previously, was investigated by determining the cytosolic ATP and Mg2+ concentrations in yeast cells grown under derepressing and repressing conditions. Derepression is accompanied by an important loss of Mg2+ from the cells, maintaining the ATP concentration constant. This produces an increase of Mg2+-free ATP in the cytosol from 0.01 mM to 0.1 mM. This free ATP concentration would lead to a maximal inhibition of hexokinase PII.

Adenosine Triphosphate↗
PubMed1982

Endoscopic cytology and biopsy diagnosis of esophageal carcinoma.

We examined 107 cytology and biopsy specimens taken simultaneously from 103 patients to determine the efficacy of cytologic esophageal brushing in the diagnosis of esophageal carcinoma. After review of all material, cytology was positive in 84% of cases, biopsy in 86%, and combined specimens (cytology and biopsy) in 94%. However, agreement as to histologic type was reached in only 53 of the 63 specimens originally reported as positive by both cytology and biopsy.

Adenocarcinoma↗
PubMedDate not supplied

Efficacy of methadone versus methadone and guanfacine in the detoxification of heroin-addicted patients.

In a randomized double-blind study, the clinical efficacy of methadone vs. methadone and guanfacine was assessed in terms of evolution of opioid withdrawal symptoms during inpatient detoxification. A total of 144 patients were included and randomly allocated to three different treatment groups: methadone alone, and two combined treatment schedules (methadone plus 3 or 4 mg of guanfacine). No differences were observed among the three groups with regard to retention rate throughout the study period. Both therapies, methadone and methadone plus guanfacine, determined a slight increase in withdrawal scores when methadone was discontinued. However, guanfacine was unable to effectively control methadone-associated withdrawal symptoms. These results indicate that guanfacine does not effectively reduce the opioid withdrawal symptoms.

Adult↗
PubMedDate not supplied

Müllerian inclusions in peritoneal washings. Potential source of error in cytologic diagnosis.

Müllerian inclusions in peritoneal washings from female patients may be mistaken for adenocarcinoma. Such findings were studied in the peritoneal washing cytology specimens from eight cases. The inclusions usually presented as tubular or papillary structures, often forming a single layer of epithelium surrounding psammoma bodies. The cells forming these structures often displayed some degree of atypia. Recognition of this entity in peritoneal fluids is important to avoid a misdiagnosis of disseminated cancer. A general outline is proposed for interpreting such findings in peritoneal washings, based on the cytomorphology of these structures as well as the microscopic features of the primary neoplasms.

Adenocarcinoma↗