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Biomedical subjects

F Contreras

Publications and source records attributed to F Contreras.

At least 19 recordsLinked to original sources
PubMed2002

Loss of the circadian variation of platelet [3H]imipramine binding in delusional compared with non-delusional endogenously depressed patients.

BACKGROUND: The circadian variations of the serotonin reuptake sites were studied in 16 patients meeting DSM-IV criteria for major depression with melancholia, either with (n=8) or without (n=8) psychotic symptomatology. METHOD: The [3H]imipramine binding sites were measured in platelet samples. RESULTS: While no statistically significant difference was found between the morning (09:00 h) and evening (21:00 h) [3H]imipramine B(max) values in the control group, both the non-delusional and delusional melancholic patients showed higher evening than morning B(max) values, which were only statistically significant in the former. When both diagnostic groups were compared, the delusional patients showed significantly lower [3H]imipramine binding values than the non-delusional patients both in the morning and evening samples. Within the non-delusional depressed patients, those individuals with mood circadian variation, assessed by the 18th item of the HDRS, showed significantly lower B(max) values than those without mood variation. Lowest morning and evening B(max) values were noted in the delusional depressed group without mood variations. CONCLUSIONS: These results suggest that delusional depressions might have a different neurobiological substrate with loss of chronobiological rhythms.

Antidepressive Agents, Tricyclic↗
PubMed2002

Dopamine, hypertension and obesity.

Dopamine, a neurotransmitter, precursor of noradrenaline, is responsible for cardiovascular and renal actions, such as increase in myocardial contractility and cardiac output, without changes in heart rate, producing passive and active vasodilatation, diuresis and natriuresis. These cardiovascular and renal actions take place through the interaction with dopamine receptors, D(1), D(2), D(3), D(4), and D(5). Recent findings point to the possibility of D(6) and D(7)receptors. Dopamine is known to influence the control of arterial pressure by influencing the central and peripheral nervous system and target organs such as kidneys and adrenal glands, in some types of hypertension. Although dopamine and its derivatives have been shown to have antihypertensive effects, these are still being studied; therefore it is important to explain some physiological and pharmacological aspects of dopamine, its receptors, and the clinical uses it could have in the treatment of arterial hypertension and more recently in obesity, based on evidence proving a clear association between obesity and the decrease in the expression of D(2) receptors in the brain of obese persons.

Angiotensin II↗
PubMed2001

Metabolism and growth of juveniles of Litopenaeus vannamei: effect of salinity and dietary carbohydrate levels.

The present study was designed to understand how carbohydrate (CBH) and protein metabolism are related in the penaeid shrimp Litopenaeus vannamei. With this information, we obtained a comprehensive schedule of the protein-carbohydrate metabolism including enzymatic, energetic, and functional aspects. We used salinity to determine its role as a modulator of the protein-carbohydrate metabolism in shrimp. Two experiments were designed. The first experiment evaluated the effect of CBH-salinity combinations in growth and survival, and hemolymph glucose, protein, and ammonia levels, digestive gland glycogen, osmotic pressure, and glutamate dehydrogenase (GDH) of L. vannamei juveniles acclimated during 18 days at a salinity of 15 per thousand and 40 per thousand. The second experiment was done to evaluate the effect of dietary CBH level on pre- and postprandial oxygen consumption, ammonia excretion, and the oxygen-nitrogen ratio (O/N) of juvenile L. vannamei in shrimps acclimated at 40 per thousand salinity. We also evaluated the ability of shrimp to carbohydrate adaptation. We made phosphoenolpyruvate carboxykinase (PECPK) and hexokinase activity measurements after a change in dietary carbohydrate levels at different times during 10 days. The growth rate depended on the combination salinity-dietary CBH-protein level. The maximum growth rate was obtained in shrimps maintained at 15 per thousand salinity and with a diet containing low CBH and high protein. The protein in hemolymph is related to the dietary protein levels; high dietary protein levels produced a high protein concentration in hemolymph. This suggests hemolymph is able to store proteins after a salinity acclimation. Depending on the salinity, the hemolymph proteins could be used as a source of osmotic effectors or as metabolic energy. The O/N values obtained show that shrimp used proteins as a source of energy, mainly when shrimps were fed with low CBH. The role played by postprandial nitrogen excretion (PPNE) in apparent heat increase (AHI) (PPNE/AHI ratio) is lower in shrimps fed diets containing high CBH in comparison with shrimps fed diets containing low CBH levels. These results confirm that the metabolism of L. vannamei juveniles is controlled by dietary protein levels, affecting the processes involved in the mechanical and biochemical transformations of ingested food. A growth depression effect was observed in shrimps fed with low-CBH protein diets and maintained in 40 per thousand salinity. In these shrimps, the hemolymph ammonia concentration (HAC) was significantly higher than that observed in shrimps fed with low CBH and maintained in 15 per thousand salinity. That high HAC level coincided with lower growth rate, which suggests that this level might be toxic for juveniles of L. vannamei. Results obtained for GDH activity showed this enzyme regulated both HAC and hemolymph protein levels, with high values in shrimps fed with low CBH levels and maintained in 40 per thousand salinity, and lower in shrimps fed with high CBH and maintained in 15 per thousand salinity. These differences mean that shrimp with a high-gill GDH activity might waste more energy in oxidation of the excess proteins and amino acids, reducing the energy for growth. It was evident that L. vannamei can convert protein to glycogen by a gluconeogenic pathway, which permitted shrimp to maintain a minimum circulating glucose of 0.34 mg/ml in hemolymph. A high PECPK activity was observed in shrimps fed a diet containing low CBH level indicating that the gluconeogenic pathway is activated, as in vertebrates by low dietary CBH levels. After a change in diet, we observed a change in PEPCK; however, it was lower and seems to depend on the way of adaptation, because it occurred after 6 days when adapting to a high-CBH diet and with little change for the low-CBH diet.

Journal Article↗
PubMed2001

Olmsted syndrome.

Olmsted syndrome is an uncommon inherited disorder of keratinization that presents mutilating palmoplantar keratoderma, perioral hyperkeratosis, leukokeratosis and alopecia. We report a case of this rare syndrome diagnosed in a 48-year-old woman and confirms the existence of a generalized abnormality in keratin expression. Immunoreactivity in our case suggests an abnormal expression of keratins 5 and 14 similar to the observed in other hyperproliferative disorders.

Abnormalities, Multiple↗
PubMed2001

beta-catenin expression in pilomatrixomas. Relationship with beta-catenin gene mutations and comparison with beta-catenin expression in normal hair follicles.

BACKGROUND: beta-catenin functions in signal transduction in the Wnt signalling pathway, which has recently been implicated in hair follicle (HF) morphogenesis. beta-catenin gene mutations affecting exon 3 have been reported in a high percentage of human pilomatrixomas. However, the expression pattern of beta-catenin in human HFs and pilomatrixomas has not been reported. OBJECTIVES: To analyse immunohistochemically the expression pattern of beta-catenin in normal anagen HFs and in 40 human pilomatrixomas. METHODS: In 11 of these tumours we also studied exon 3 beta-catenin gene mutations by polymerase chain reaction and direct sequencing. As these mutations have been related to a replication error (RER) phenotype in other tumour types, we explored whether or not this association also occurs in pilomatrixomas. RESULTS: beta-catenin was expressed in the cell membranes of the outer and inner root sheaths and in matrix cells located at the base and periphery of the HF bulb. However, central matrix cells that differentiate into cortical cells, cortical and cuticular cells expressed beta-catenin in the nucleus, suggesting a role in signal transduction. In addition, some fibroblasts of the dermal papilla also showed nuclear expression of beta-catenin. All 40 analysed pilomatrixomas showed intense nuclear and cytoplasmic beta-catenin expression in proliferating matrix (basaloid) cells. In areas of maturation, transitional cells mainly showed cytoplasmic and membranous expression of beta-catenin, while only a few cells retained nuclear expression. Shadow or ghost cells did not show beta-catenin expression. Three of 11 tumours (26%) had beta-catenin mutations. All three had the same heterozygote mis-sense mutation: a G to T change affecting the first nucleotide at codon 32 (D32Y). None of the 11 tumours studied had a positive RER phenotype. CONCLUSIONS: Present and previous studies suggest that the Wnt/beta-catenin/Tcf-Lef pathway is activated in normal matrix cells of the HF to induce differentiation to the hair shaft. Additionally, the beta-catenin mutation in matrix cells of the HF stabilizes beta-catenin protein, which translocates into the nucleus, where it activates of gene transcription together with lymphoid enhancer factor-1 producing pilomatrixoma. These mutations occur without an underlying defect in DNA mismatch repair.

Adolescent↗
PubMed2001

Pilomatrix carcinoma: a clinicopathologic study of six cases and review of the literature.

Pilomatrix carcinoma, the malignant variant of pilomatrixoma, is a rare entity. The authors report on six patients with pilomatrix carcinoma and review the pertinent literature. The lesions showed a predilection for elderly individuals (mean age, 61 years) with a male:female ratio of 5:1, and they presented as dermal or subcutaneous tumors located on the head and neck (5 neoplasms) and chest (1 neoplasm). Tumors varied in size from 0.6 cm to 2.5 cm (mean, 1.78 cm). None of the lesions recurred after wide local excision. On scanning magnification, all tumors showed the architectural features of a malignant neoplasm (asymmetry and poor circumscription, presence of several markedly sized and variably shaped basaloid aggregations, and ulceration). The tumors were composed of pleomorphic basaloid cells with prominent nucleoli and frequent atypical mitoses accompanied by central areas with keratotic material, shadow cells, and foci of necrosis. The tumor nests were surrounded by a desmoplastic stroma and infiltrated the adjacent tissues. Vascular or perineural infiltration was not observed. In one case, the basaloid cells contained abundant melanin pigment in their cytoplasms. Pilomatrix carcinoma is a neoplasm of low-grade malignancy that should be distinguished from the conventional pilomatrixoma and its variants (aggressive pilomatrixoma and proliferating pilomatrixoma), matricoma, and basal cell carcinoma with matrical differentiation. Clinicians and pathologists should be aware of the occurrence of pilomatrix carcinoma because of its potential for distant metastases.

Adult↗
PubMed2000

Endothelial dysfunction in arterial hypertension.

Systemic arterial pressure is a dynamic and reactive physiological parameter depending on a great many factors. The endothelial cells of the vascular system are responsible for many biochemical reactions maintaining vascular homeostasis and therefore arterial pressure. Arterial hypertension, atherosclerosis and endothelial dysfunction constitute risk factors increasing morbidity and mortality of cardiovascular origin. These three elements are closely related and frequently act simultaneously damaging different organs. In this paper we review the physiology of the endothelium and the probable consequences of endothelial dysfunction on the pathophysiology of arterial pressure.

Arteries↗
PubMed2000

Diabetes and hypertension physiopathology and therapeutics.

Diabetes mellitus by itself, is a frequent and increasing public health problem. The prevalence in most Western countries varies between 2 to 5% and it is rapidly increasing in Asiatic countries due to changes in dietary habits during the last years. The association between diabetes mellitus and hypertension has been described in 60 to 65% of diabetics. In hypertension we find insulin resistance mainly in skeletal muscle involving the conversion of glucose to glycogen independently of blood flow. The degree of resistance is related to the severity of hypertension and varies between races. States of hyperinsulinaemia and insulin-resistance have been postulated as causes and/or consequences of hypertension. Regardless of the type of diabetes, hypertension is two to three times more common among diabetics compared with non-diabetics. In this paper we propose to review the essential physiopathological mechanisms involved in this association that causes high morbidity and mortality rates and increases disability among the population involved.

Antihypertensive Agents↗
PubMed2000

Two cases of segmental multiple glomangiomas in a family: type 1 or type 2 segmental manifestation?

Several autosomal dominant skin diseases may manifest cutaneous mosaicism. Two types of segmental arrangement can be distinguished: type 1 is characterized by segmental lesions with similar severity to that observed in the diffuse phenotype, the remaining skin being normal; type 2 is characterized by segmental lesions showing a major degree of severity and milder lesions diffusely arranged. Multiple glomus tumours have recently been included in the group of genodermatoses showing type 2 segmental involvement. A family with 2 cases of multiple glomangiomas arranged in a segmental fashion is reported. A 12-year-old girl presented multiple nodular glomangiomas on her right buttock and thigh, in a band-like distribution. A sister of her paternal grandfather showed plaque-like multiple glomangiomas on her left thigh and various glomangiomas on her right buttock and arm. No other family members were known to be affected. Two new cases of familial segmental multiple glomangiomas are reported, with the particularity that one of these exhibited type 2 segmental manifestation and the other type 1 from a clinical point of view.

Child↗
PubMed1999

Syphilis in an HIV infected patient misdiagnosed as leprosy.

A 42-year-old man with uveitis and a widespread cutaneous eruption, histopathologically characterized by dermal granulomatous infiltrates with perineurial invasion, was incorrectly diagnosed and treated as having borderline leprosy. Further studies demonstrated secondary syphilis and human immunodeficiency virus (HIV) infection. Standard penicillin therapy resolved his cutaneous and ocular lesions. Reports on clinical and pathological findings of active syphilis in HIV infected patients are scarce but this case and isolated previous case reports suggest that granulomatous infiltrates might be a common feature in secondary syphilis with short evolution in HIV infected patients.

Adult↗
PubMed1998

Multibacillary leprosy: lesions with macrophages positive for S100 protein and dendritic cells positive for Factor 13a.

In the defense against Mycobacterium leprae, macrophages play an essential part in the mechanism of bacterial lysis but require the presence of cytokines such as interleukin 2 and gamma interferon from lymphocytes in order to effectively kill the organisms in any number. While there have been many studies of the lymphocytes in lesions of leprosy, less attention has been given to the immunohistochemical characterization of the macrophage populations. In this study, the cutaneous lesions of 69 patients with leprosy (42 lepromatous, 5 mid-borderline, and 22 tuberculoid) were evaluated by immunohistochemistry for the expression of S100 protein, CD1a, CD68, muramidase, HLA-DR, and Factor 13a. The macrophages from lesions of polar, subpolar, and borderline lepromatous leprosy patients expressed S100 protein intensely and constantly. In contrast, the lesions of polar and subpolar tuberculoid leprosy had very few cells that were immunoreactive for S100 protein ('S100+') in the granulomas in the dermis. The macrophages in all lesions were reactive for CD68 and muramidase. In paraffin sections, macrophages of lepromatous lesions failed to stain for HLA-DR, whereas in tuberculoid lesions, they were strongly positive for HLA-DR. Three patients with histoid leprosy (relapse lesions) had lesions that were strongly positive for Factor 13a and were negative for S100 protein ('S100-'). Given the possible chemotactic and migration inhibition effects of the calcium-binding proteins of the S100 family, these data suggest a possibly important role for S100 protein in the accumulation of macrophages in lepromatous leprosy, and also reveal infection of Factor 13a + dermal dendritic cells in histoid leprosy.

Antigens, CD↗
PubMed1997

Nonscarring alopecia associated with solitary circumscribed neuroma.

We report an unusual case of nonscarring alopecia clinically resembling patchy alopecia areata around central solitary circumscribed neuroma. Prompt and spontaneous complete hair regrowth was observed after removal of the tumor. Further knowledge of growth factor and receptor interaction in regulating the hair follicle cycle, as well as on the production of growth factors and cytokines by tumor cells and/or cells within the tumor microenvironment may contribute to better understand the pathologic mechanisms underlying certain curious phenomena such as peritumoral nonscarring alopecia.

Aged↗