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Biomedical subjects

F Díaz

Publications and source records attributed to F Díaz.

At least 73 records · Page 4Linked to original sources
PubMed1997

Auditory event-related potentials in mentally retarded subjects during active and passive oddball experiments.

Auditory event-related potentials were recorded from subjects performing an active and/or a passive oddball task. The subjects belonged to three groups: 27 nonretarded (NR) subjects; 39 "discriminating" retarded (DR) subjects; and 12 "nondiscriminating" retarded (NDR) subjects. With respect to NR subjects, DR subjects had significantly longer latencies for peaks N1, P2, N2 and P3 in the active task and for N2 in the passive task, and NDR subjects had significantly longer latencies for peaks N2 and P3 in the passive task. We conclude: that the generation of P3 may involve both a permanent automatic basis and controlled processes whose intervention depends on the attention paid to the P3-inducing stimuli; and that whether a mentally retarded subject exhibits significantly lengthened P3 latency in a particular task depends on the degree to which the cognitive processes involved in performance of that task are affected by the causes of his or her retardation.

Adolescent↗
PubMed1997

Quantitative morphological changes in neurons from the dorsal lateral geniculate nucleus of young and old rats.

BACKGROUND: We studied the morphological changes occurring in neurons from the dorsal lateral geniculate nucleus (dLGN) during aging by analysing the size and shape of cell bodies and nuclei. METHODS: Male albino Wistar rats, aged 3, 18, 24, and 30 months, were used. After appropriate tissue preparation and following the usual histological procedure, the profiles of 1,920 neuronal bodies and nuclei were drawn using a camera lucida. Data was later recorded and processed with a semiautomatic image analyser. RESULTS AND CONCLUSIONS: We observed that dLGN neurons do not change in size from the age of 3-24 months. Between 24 and 30 months, the soma and nucleus of the cell undergo hypertrophy, 32.8% and 35.6%, respectively, when compared to those from 3-month-old animals (P < 0.01). Furthermore, we found a high correlation between cell body size/nucleus size, which does not disappear with age. The r values (correlation coefficient) were 0.7998, 0.8662, 0.8433 and 0.7304, and R2 (determination coefficient) was equal to 0.6397, 0.7504, 0.7112, and 0.5335. These latter values show that in 63.97%, 75.04%, 71.12%, and 53.35% of cases, respectively, modifications in somata size were accompanied by similar changes in nucleus size, and vice-versa. The study of the shape of the soma and nucleus of the cell revealed that both structures have a rounded-oval configuration that does not change in a significant way from adulthood to old age.

Aging↗
PubMed1997

Effect of the environment on fetal skin wound healing.

Skin wound healing has been shown to be a different process in the fetus than in the adult animal. Some of these differences have been attributed to the unique fetal environment (i.e., amniotic fluid). The aim of the present study is to compare fetal skin healing in intraamniotic and extraamniotic wounds. A fetal rabbit model has been used in which three types of skin wounds were induced on 23-day-old fetuses in contact with either amniotic fluid or maternal peritoneal fluid. The wounds consisted of a sutured skin incision, a nonsutured incision, and an electrocautery burn. Seven days later all wounds were examined mechanically (scar resistance), biochemically (collagen and noncollagen protein concentration), and histologically. Biochemical and growth factor studies of both environments, the amniotic and the peritoneal fluids, were also conducted. The results showed excellent healing by first intention and absence of healing by second intention in both environments, greater scar resistance in the intraperitoneally positioned fetal wounds, and a higher concentration of insulin-like growth factor-1 (IGF-1) in the peritoneal fluid than in the amniotic fluid. It can be concluded that fetal skin wounds in contact with peritoneal fluid show the same healing pattern as in the natural fetal environment (amniotic fluid). The higher concentration of IGF-1 in the peritoneal fluid suggests that this growth factor, through its relationship with the growth hormone, plays a role in increasing the scar resistance of fetal skin wounds in contact with maternal peritoneal fluid.

Amniotic Fluid↗
PubMed1997

Bronchiolitis obliterans in a patient with HIV infection.

Bronchiolitis obliterans, with or without organizing pneumonia, represents an uncommon response of the lung to several injuries, that results in characteristic histopathologic changes in the small airways. The present case report describes a patient with HIV infection who developed bronchiolitis obliterans, and reviews the previously reported cases of this condition in HIV-infected patients.

Adult↗
PubMed1997

DNA ploidy changes in rhino mouse skin induced by all-trans retinoic acid and retinol.

OBJECTIVE: In order to assess the proliferative changes induced by all-trans retinoic acid (RA) and retinol (ROL), we have carried out a study of the DNA content of basal and suprabasal keratinocytes after epicutaneous application on the rhino mouse. STUDY DESIGN: Skin sections were analyzed stereologically and cytophotometrically using the Feulgen technique. The diploid DNA value (2C) was obtained from hepatocyte nuclei of control animals. Whereas cells in phase G0-G1 will show a 2C content, cells during phase S and in phase G2-M will show DNA values ranging from 2C to 4C and 4C, respectively. RESULTS: Although epidermal thickness (ET) increased significantly in all treated animals, surface density only increased in animals treated with all-trans RA. Quantification of DNA content of basal keratinocytes showed reduction of 2C and 2C-4C populations with a commensurate increase in proportions of cells with 4C and > 4C in the animals treated with 0.025% all-trans RA and ROL. Suprabasal keratinocytes of mice treated with 0.025% all-trans showed a decrease of the 2C population and an increased proportion of cells with 4C. Whereas 0.025% all-trans RA induced an increase of both basal and suprabasal DNA indices, ROL enhanced only the basal DNA index significantly. CONCLUSION: Animals treated with 0.025% ROL showed a significant increase in the basal proliferative index (PI) while the suprabasal PI remained constant; treatment with 0.025% all-trans RA produced a significant increase of both basal and suprabasal PIs and parakeratotic hyperkeratosis probably due to incomplete differentiation.

Administration, Cutaneous↗
PubMed1997

Plasma levels of beta-endorphin during the menstrual cycle.

During recent years, many research teams have suggested a possible role of endogenous opiates in the control of the menstrual cycle. The level of immunoreactive beta-endorphin was measured on different days during the ovulatory cycle of 131 healthy volunteers. The levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), 17 beta-estradiol and progesterone were also measured. The graphic representation of opiate levels during the female menstrual cycle, where day O is the day of ovulation, shows that plasmatic beta-endorphin levels are not stable throughout. The levels increase progressively during the follicular phase, reaching a maximum (mean 139.49 pg/ml, SD 42.23 pg/ml, 95% confidence interval 121.22-157.75 pg/ml) 4 days before ovulation. During the periovulatory period (days-3 to +3) levels of beta-endorphin are very stable (mean day 0, 27.8 pg/ml, SD 6.36 pg/ml, 95% confidence interval 19.29-27.83 pg/ml) and low (p < 0.05), followed by a renewed increase during the luteal phase (mean day + 5, 87.86 pg/ml, SD 36.49 pg/ml) where a maximum level (mean 102.78 pg/ml, SD 30.35 pg/ml) is reached 24 h before the next menses. The beta-endorphin level has a negative correlation with the LH level (r = -0.50, p < 0.001) on the preovulatory days, and during the luteal phase a positive linear correlation (r = 0.47, p < 0.001) is found with the progesterone level. It seems that beta-endorphin levels in the plasma are influenced by the ovarian steroids. However, the influence of the plasmatic opiate on the gonadotropins is currently under discussion.

Adolescent↗
PubMed1997

[Cat-scratch disease. A report of 4 cases and a review of the literature].

Four cases of cat-scratch diseases are here reported and a review of the literature is made. The disease, apart from its typical presentation form as a usually self-limited regional lymph node enlargement, can occasionally spread and involve several organs systems. Indirect immunofluorescence serological tests have been of help for its diagnosis and should be included among the diagnostic criteria for the disease. In particular cases, nuclear magnetic resonance can be useful to suggests the diagnosis.

Adolescent↗
PubMed1997

PSA excess in the differential diagnosis of prostate carcinoma.

OBJECTIVE: To evaluate the efficiency of PSA excess in distinguishing prostate cancer (PC) in its early stages from benign prostatic hypertrophy (BPH) and compare it with the efficiency of serum PSA. METHODS: A cross-sectional study was carried out on 27 patients with PC and 46 with BPH, whose serum PSA and prostatic volume were determined. PSA excess was calculated as the difference between serum PSA and predicted PSA according to the gland volume, calculating the latter as the prostatic volume multiplied by factor 0.3 ng/ml/g. RESULTS: PSA excess values were significantly higher in patients with PC, while serum PSA levels were not different between the two populations studied. Receiver operating curves (ROC plots) showed a higher diagnostic utility for PSA excess, with a maximum efficiency of 73% at a cut-off point of -13 ng/ml. The predictive value of a positive result is slightly higher for serum PSA, but PSA excess showed a predictive value of a negative result superior to that of PSA.

Adenocarcinoma↗
PubMed1996

[Retrospective multicenter study of the efficacy of interferon alpha in chronic hepatitis C].

BACKGROUND: Until very recently, interferon (INF) in Spain was authorized in chronic hepatitis C (C-HCV) at a dosis of 3 megaunits (mu) for 6 months. Nonetheless, the rate of maintained complete response is lower than that obtained with more prolonged treatments. The first aim of this study was to retrospectively know the effectiveness of alpha INF in patients treated for 6 or 12 months with a dosis of 3 or 5-6 MU. The second was to analyze the characteristics of the patients who achieved a maintained complete response. PATIENTS AND METHODS: Patients with C-HCV treated in 9 hospitals in Andalucía, Spain who fulfilled the following conditions were retrospectively analyzed: liver biopsy prior to treatment, positive test for anti HCV and a follow up of at least 6 months after alpha INF treatment. A total of 344 patients were studied: 267 treated with alpha INF-2b, 51 with alpha INF-2a and 26 with lymphoblastoid INF. One hundred ninety-five patients were treated for 6 months and 149 for 12 months. RESULTS: Seventy-seven (22%) of the patients presented maintained complete response, 170 (50%) did not respond and 97 (28%) relapsed. On comparing the three types of interferon used over 6 months, no significant differences were observed. Neither were differences found on comparing the dosis of 3 mu versus 5 or 6 mu. On analyzing the treatments of 6 and 12 months, the following was observed, respectively: maintained complete response 15% vs 32%, relapse 29% vs 30% and non responders 57% vs 38% (p < 0.001). Multivariate analysis demonstrated that the patients who responded the best to INF were those who presented the following characteristics: female sex, age under 40 years last, history of transfusion or IVDA, basal GPT level higher than 145 IU/I, GGT less than 55 IU/I, less evolved histologic lesions and duration of treatment over 12 months. CONCLUSIONS: Of the different treatments analyzed with alpha interferon in chronic hepatitis C, the best was found to be that with 3 mu during 12 months.

Adult↗
PubMed1996

Functional sexual dimorphism of the nucleolar organizer regions in the tuberomamillary nucleus.

The tuberomamillary nucleus (TM) is a cluster of magnocellular neurons that are located close to the mamillary recess or basal surface of the mamillary body (MBs) and is the only known source of histamine (HA). The nucleolar organizer regions (NORs) of the nervous cells of the subnuclei E1, E2 and E3 of the TM are quantified in this paper to discern the existence of possible sexual differences in the overall neuronal protein synthesis between male and female rats in two phases of the oestrous cycle (oestrous-dioestrous). We have used the argentic impregnation technique of the NORs (AgNORs) in both bilateral nuclei of the TM and found functional bilateral symmetry in its AgNORs. Furthermore, we demonstrate the existence of significant differences (P < 0.001) between sexes and between two phases of the oestrous cycle studied (oestrous-dioestrous) in the parameter of number of AgNORs per neuron. Hormonal manipulation of the TM in the rat during the two periods, postnatal or adult, shows the importance of the activational effect of the hormones on the activity of cellular protein synthesis.

Aging↗
PubMed1996

Quantitative histochemical study of cytochrome oxidase in the dLGN of aging rats.

We carried out a quantitative histochemical study of the enzyme cytochrome oxidase (CO) in neurons of the dorsal lateral geniculate nucleus (dLGN) of male Wistar rats aged 3, 18, 24 and 28 months. The results show that the activity of cytochrome oxidase decreases significantly between 24 and 28 months. We also checked whether a correlation existed between neuronal size and enzymatic activity. Low correlation coefficients were obtained which were between 0.4139 at 3 months 0.2092 at 28 months. Nevertheless, we observed a certain relationship between both parameters, and therefore we classified the neurons as light, moderate and dark according to their optical density, which correlates with enzyme cytochrome oxidase activity, and as small, medium and large depending on their size. We found that light neurons were scarcely represented in the dLGN. At the age of 3 months, the most frequent neurons were moderate, medium-size ones, and dark, small ones. The population of moderate neurons increased with age, reaching 74.5% at the 28th month, 52.2% of which corresponded to medium-size neurons. In the same group dark neurons decreased, falling to a total of 15.3% made up of medium and large-size ones. These results could be interpreted as reflecting a decrease in the bioenergetic competence of the neurons of this nucleus in old age.

Aging↗
PubMed1996

The effect of ageing on neurones in the visual sector of the thalamic reticular nucleus.

This paper studies the quantitative morphological changes occurring during ageing in neurones of the dorsocaudal or visual sector of the thalamic reticular nucleus. Male Wistar rats aged 3, 6, 18, 24 and 30 months were used in this study which applied morphometric methods. We have observed an increase in the size of neurones from this sector between the 3rd and 24th month and a decrease between the 24th and 30th month. In all the ages studied the majority of neurones are fusiform.

Aging↗
PubMed1996

Mesenchymal chondrosarcoma of the foot, an unusual location: case report and review of the literature.

We present a case of primary mesenchymal chondrosarcoma of the proximal phalanx of the first toe. The bones of the foot represent an infrequent primary site for this neoplasm. The tumour consisted of layers of undifferentiated round cells with scanty cytoplasm and hyperchromatic nuclei. The presence of brain, lung, and left auricle metastasis was demonstrated, and the patient died due to brain edema 18 days after admission. Mesenchymal chondrosarcoma is a rare tumor that more frequently involves the pelvic bones, the femur, and the humerus. To our knowledge, only nine cases of primary mesenchymal chondrosarcoma arising from the bones of the foot have been previously reported, with none involving the phalanx of the toe.

Adult↗
PubMed1996

Evaluation of a directly observed six months fully intermittent treatment regimen for tuberculosis in patients suspected of poor compliance.

BACKGROUND: Although a priority for tuberculosis control is to achieve the maximum cure rate, compliance with chemotherapy in specific high risk groups (homeless, intravenous drug abusers, chronic alcoholics) is usually poor. METHODS: From January 1990 to December 1994 102 patients with tuberculosis (96 pulmonary, six extrapulmonary) who were poorly compliant with treatment were treated with a six month fully intermittent (twice weekly) directly observed regimen. They comprised 71 homeless subjects, 50 chronic alcoholics, 23 intravenous drug abusers, nine infected with HIV, and 11 who had previously abandoned a daily antituberculosis regimen; 53 had more than one of these risk factors. Treatment included isoniazid and rifampicin for six months and pyrazinamide during the first two months. Patients who failed to take their medication on two consecutive occasions were actively sought by telephone or by personal search. RESULTS: After two months of treatment 95 of the 102 patients had taken their medication regularly and 90 of them had negative cultures. Four of the remaining patients had negative cultures after three months. At the end of the six months 87 patients had completed treatment and were considered cured. Only 15 patients abandoned the treatment (13 of whom had more than one risk factor). Only three relapses occurred in the 102 patients at one year follow up and in the 88 patients followed for two years. Two patients required a change of treatment due to major side effects. Although intravenous drug abuse was the only predictor of non-compliance in the multivariate analysis, if the available variables in the second month of treatment were analysed, current poor compliance and abandonment of treatment in the past were found to be significantly associated with non-compliance. CONCLUSIONS: This study shows the efficacy of this intermittent regimen and the effectiveness of a directly observed treatment programme.

Adolescent↗
PubMed1996

Sulfadiazine-induced multiple urolithiasis and acute renal failure in a patient with AIDS and Toxoplasma encephalitis.

OBJECTIVE: To report a patient with sulfadiazine-induced urolithiasis and acute renal failure. CASE SUMMARY: A patient with AIDS who was being treated with pyrimethamine and sulfadiazine for Toxoplasma encephalitis developed lumbar pain, dysuria, urinary frequency, and hematuria. Acute renal failure was found and numerous crystals of sulfadiazine were seen in the urine. Multiple calculi of up to 2 cm in diameter in both kidneys were noted on ultrasound. The patient was treated with intravenous fluids and alkalinization of the urine with rapid improvement. An intravenous urographic study performed 2 days later showed no evidence of calculi and renal function was normal. DISCUSSION: Patients with AIDS and Toxoplasma encephalitis may have several predisposing conditions that can lead to the development of sulfadiazine-induced crystalluria, including poor fluid intake, fever, diarrhea, and hypoalbuminemia, in addition to the high doses of the drug required and the prolonged period of treatment. CONCLUSIONS: This potentially serious complication can be managed easily with conservative treatment. Clinicians should be aware of this complication as it is expected to occur more frequently as more patients are treated with sulfonamides and patients with AIDS experience longer survival rates.

AIDS-Related Opportunistic Infections↗
PubMed1996

[Bradycardia and asystolia secondary to epileptic crisis. Report of a case].

We report the case of a 21 year old man with bradycardia and asystolia after a seizure. No cardiac disease could be demonstrated, but electroencephalography after sleep deprivation showed the presence of a temporal irritative focus. The importance of differential diagnosis between cardiogenic syncope and loss of consciousness due to epilepsy is discussed.

Adult↗