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Biomedical subjects

I Silva

Publications and source records attributed to I Silva.

At least 37 records · Page 2Linked to original sources

Molecular analysis of ras oncogenes in CIN III and in stage I and II invasive squamous cell carcinoma of the uterine cervix.

AIM: To examine the prevalence of genital type human papilloma virus (HPV) and mutations at codons 12, 13, and 61 in H, Ki, and N-ras in CIN III and early invasive squamous cell carcinomas of the cervix. METHODS: Prevalence of HPV was examined in 20 CIN III and 20 stage I and II cervical carcinomas, using non-isotopic in situ hybridisation (NISH) and solution phase polymerase chain reaction (PCR). In addition, mutations at codons 12, 13, and 61 were examined in H, Ki, and N-ras in these CIN III and early invasive squamous cell carcinomas, to assess the prevalence of ras gene point mutations and to define where in the pathobiology of squamous cell carcinoma such events occur. A non-isotopic PCR/RFLP assay was used to define these mutations. RESULTS: Of the 20 CIN IIIs examined, 19 contained HPV 16 DNA sequences by PCR and NISH. Dual infection was not uncovered. The 20 early (stage I and II) invasive squamous cell carcinomas showed predominant HPV 16 positivity (17/20), with one case HPV 18 positive, confirmed on PCR and NISH. Activating mutations were not identified in any of the CIN III cases. Only one stage I, HPV 16 positive carcinoma showed an activating mutation in H-ras codon 12, which was not present in adjacent normal ectocervical mucosa from the same patient. CONCLUSIONS: ras Activation does not appear to occur in conjunction with HPV infection, particularly of HPV 16 infected high grade cervical intraepithelial neoplasia, or to occur commonly in early cervical squamous cell carcinoma. The postulated model of HPV linked carcinogenesis suggests malfunctional control of viral transcription as a necessary component of neoplastic progression. It is also clear that host gene alterations are equally necessary for HPV linked carcinogenesis to occur.

Carcinoma, Squamous Cell↗

A novel, rapid in cell RNA amplification technique for the detection of low copy mRNA transcripts.

Growing interest now focuses on improvements of in situ polymerase chain reaction (PCR) technology for the detection of DNA and RNA cellular sequences. In this study, reverse transcription PCR in situ hybridisation (RT PCR-ISH) was developed and used to determine gene expression of pyruvate dehydrogenase in a cell model system, using human peripheral blood lymphocytes (PBLs). The success of in cell RNA amplification depends on the type of cell/tissue fixation, cell permeabilisation, and the efficiency of reverse transcription and cDNA amplification. This paper presents new approaches to overcome the critical aspects of fixation, permeabilisation, and reverse transcription when performing in cell RNA amplification. A novel fixative, "Permeafix", possessing fixative and permeabilisation properties, was used for cell fixation procedures. "Permeafix" obviated the need for pre-amplification proteolysis, facilitating entry of PCR reagents to target sequences within the cell. In addition, a simple on step RNA in cell amplification protocol using recombinant Thermus thermophilus (rTth) DNA polymerase, which reverse transcribes mRNA efficiently to cDNA and then catalyses cDNA amplification, was used. The value of a semi-junctional primer system for in cell gene expression studies, without the need to perform DNase digestion, is demonstrated.

DNA Primers↗

DNA aneuploidy by flow cytometry is an independent prognostic factor in gastric cancer.

In the present study the prognostic value of both DNA ploidy and the proliferative activity of tumour cells were studied in a series of 76 consecutive patients suffering from gastric tumours. DNA ploidy and the proliferative index (as measured by the percentage of S-phase cells) were determined by flow cytometry using fresh tumour specimens. The presence of DNA aneuploid clones by flow cytometry was detected in 62% of the cases (mean DNA index of 1.63 +/- 0.46; range 1.08-2.92), the mean proportion of S-phase cells being of 18.4 +/- 11.5%. In comparison with diploid cases, aneuploid tumours showed a higher proliferative activity (cases with more than 15% S-phase cells: 18.4% versus 6.1%, p = 0.0001) as well as a higher incidence of node involvement (95% versus 68%, p = 0.001). By contrast, no significant differences were detected with respect to sex, age, histologic grade and type, clinical stage, tumour size and the incidence of extranodal involvement. Upon grouping the patients according to the proportion of S-phase cells no significant differences were observed for the clinical and biological parameters explored except for an association between a high percentage of S-phase cells and the presence of DNA aneuploidy (40% versus 96%, p = 0.0001). Regarding survival the presence of DNA aneuploidy was significantly associated with poor outcome as compared to the diploid cases (median of 15 versus 26 months, p = 0.005). By contrast, the proportion of S-phase cells did not predict patients's outcome. Multivariate analysis of prognostic factors showed that the presence of DNA aneuploidy (p = 0.003) together with the histologic type (p = 0.03) and the existence of extranodal metastases (p = 0.05) were the best combination of prognostic factors for survival prediction.

Aged↗

Blood pressure excess for the early identification of gestational hypertension and preeclampsia.

We have examined prospectively whether the combined approach of establishing tolerance intervals for the circadian variability of blood pressure (BP) as a function of gestational age, and then determining the so-called hyperbaric index (area of BP excess above the upper limit of the tolerance interval) by comparison of any patient's BP profile (obtained by ambulatory monitoring) with those intervals provides a high sensitivity test for the early detection of pregnant women who subsequently will develop gestational hypertension or preeclampsia. We analyzed 657 BP series from 92 women with uncomplicated pregnancies and 378 series from 60 women who developed gestational hypertension or preeclampsia. BP was sampled for about 48 hours once every 4 weeks after the first obstetric consultation. Circadian 90% tolerance limits were determined as a function of trimester of gestation from 497 series previously sampled from a reference group of 189 normotensive pregnant women. The hyperbaric index was then determined for each individual BP series in the validation sample. Sensitivity of this test for diagnosing gestational hypertension was 93% for women sampled during the first trimester of gestation and increased up to 99% in the third trimester. The positive and negative predictive values were above 96% in all trimesters. Despite the limitations of ambulatory monitoring, the approach presented here, now validated prospectively, represents a reproducible, noninvasive, and high sensitivity test for the very early identification of subsequent gestational hypertension and preeclampsia, on the average, 23 weeks before the clinical confirmation of the disease.

Blood Pressure↗

[Giant-cell tumor of bone].

Giant-cell bone tumors are a rare entity. Only 7.5 to 15% are malignant tumors and correspond to 0.5% of all primary malignant bone tumors. This case report has an unusual localization (ischium) for this kind of tumor (+/- 0.6%). The patient was treated with radiotherapy alone, because local extension of the disease would require very aggressive surgery with functional implications. Ten years after treatment, the patient is alive without clinical evidence of disease, and without functional impairments.

Bone Neoplasms↗

Angiomatoid fibrous histiocytoma of the arm treated by radiotherapy for local recurrence--case report.

The Angiomatoid Fibrous Histiocytoma is a rare tumor of soft tissues, which occurs mainly in children and young adults, with low malignancy grade. It has the capacity of local recurrence, but rarely metastizes. It is frequently difficult to differentiate this from vascular tumors, namely hemangioendotheliomas and angiosarcomas, or simply organized hematomas. The authors present a case of a patient with an angiomatoid fibrous histiocytoma of the arm, treated with radiotherapy after three postsurgical recurrences.

Arm↗

Time-dependent effects of low-dose aspirin administration on blood pressure in pregnant women.

This study investigated the effects of low-dose acetylsalicylic acid (aspirin) on blood pressure in pregnant women who were at risk of developing gestational hypertension or preeclampsia and who received aspirin at different times of the day according to their rest-activity cycle. A double-blind, randomized, controlled trial was conducted in 100 pregnant women. Blood pressure for each subject was automatically monitored for 2 days every 4 weeks from the day of recruitment until delivery. Women were randomly assigned to one of six groups according to treatment (placebo, 50 subjects or aspirin, 100 mg/d, starting at 12 to 16 weeks of gestation) and the time of treatment: on awakening (time 1), 8 hours after awakening (time 2), or before bedtime (time 3). Results indicated that there was (1) no effect on blood pressure from placebo at any time (P>.212) and (2) a highly statistically significant (P<.001) time-dependent effect on blood pressure from aspirin. There was no effect of aspirin on blood pressure at time 1 (compared with placebo), but the blood pressure reduction was highly statistically significant after time 2 and, to a greater extent, after time 3 (mean reduction of 12 and 8 mm Hg in 24 hours for systolic and diastolic blood pressure, respectively, at the time of delivery compared with placebo given at the same time). These time-dependent effects of aspirin on blood pressure should be taken into account for the optimization of long-term aspirin administration at low doses for prevention of preeclampsia. In any meta-analysis of aspirin effects, inquiries about the time when the subjects took the drug are indicated and may account for discrepancies in the literature.

Adolescent↗

Blood pressure variability during gestation in healthy and complicated pregnancies.

The evaluation of predictable variability in blood pressure by the use of ambulatory devices, and the proper processing of the time series thus obtained, can be useful for the early assessment of hypertensive complications in pregnancy. We have used this approach to quantify a predictable pattern of blood pressure and heart rate throughout pregnancy in clinically healthy women as well as in pregnant women who developed gestational hypertension or preeclampsia. We analyzed 503 blood pressure series from 71 healthy pregnant women and 256 series from 42 women who developed gestational hypertension or preeclampsia. Blood pressure monitoring (48-hour) was done once every 4 weeks after the first obstetric consultation. The pattern of variation along gestation of the 24-hour mean of blood pressure for groups of normotensive and hypertensive pregnant women was established by polynomial regression analysis. This method revealed predictable patterns of variation of 24-hour means with gestational age: for normotensive pregnant women, results indicate a steady decrease in blood pressure up to the 21st week of pregnancy, followed by an increase in blood pressure up to the day of delivery. This pattern of variation is not found in pregnancies complicated with gestational hypertension or even preeclampsia: the 24-hour mean of blood pressure is stable until the 22nd week of pregnancy and then correlated with gestational age, indicating a significant linear increase of blood pressure in the second half of pregnancy. For both healthy and complicated pregnancies, heart rate slightly increases until the end of the second trimester, and it is stable thereafter. This study confirms and extends to ambulatory everyday life conditions the predictable pregnancy-associated variability in blood pressure. The differences between uncomplicated and complicated pregnancies offer new end points for an early identification of gestational hypertension and preeclampsia.

Blood Pressure↗

High sensitivity test for the early diagnosis of gestational hypertension and preeclampsia. I. Predictable variability of cardiovascular characteristics during gestation in healthy and hypertensive pregnant women.

The evaluation of predictable variability in blood pressure and heart rate by (a) the use of fully ambulatory devices, and (b) the proper processing of the time series thus obtained, can be useful in assessing early cardiovascular disease risk in pregnancy. We have used this approach to quantify a predictable time structure of blood pressure throughout pregnancy in clinically healthy women as well as in pregnant women who developed gestational hypertension of preeclampsia. We analyzed a total of 745 blood pressure series sampled by ambulatory monitoring for about 48 hours in each of several occasions in 189 women with uncomplicated pregnancies, 71 with gestational hypertension, and 29 with preeclampsia. The pattern of variation along gestation of the 24-hour mean of blood pressure for groups of normotensive and hypertensive pregnant women was established by polynomial regression analysis. Regression analysis revealed predictable patterns of variation of 24-hour means with gestational age: for normotensive pregnant women, results indicate a steady decrease in blood pressure up to the 20th week of pregnancy, followed by an increase in blood pressure up to the day of delivery. Women with gestational hypertension or preeclampsia are characterized, however, by a continuous linear increase of blood pressure with gestational age, starting from the beginning of pregnancy. This study confirms and extends to ambulatory everyday life conditions the predictable pregnancy-associated variability in blood pressure. The differences between uncomplicated and complicated pregnancies offer new endpoints for an early identification of gestational hypertension and preeclampsia.

Blood Pressure↗

High sensitivity test for the early diagnosis of gestational hypertension and preeclampsia. IV. Early detection of gestational hypertension and preeclampsia by the computation of a hyperbaric index.

UNLABELLED: The aims of this study were to examine whether the combined approach of 1) establishing tolerance intervals for the circadian variability of blood pressure as a function of gestational age, and 2) computing the hyperbaric index by comparison of any patient's blood pressure profile (obtained by ambulatory monitoring) with the tolerance limits, provides a new highly sensitive test for the early detection of gestational hypertension and preeclampsia. We analyzed a total of 745 blood pressure series sampled by ambulatory monitoring for about 48 hours in each of several occasions in 189 women with uncomplicated pregnancies, 71 with gestational hypertension, and 29 with preeclampsia. After synchronization of all data by expressing times of sampling in hours from bed-time, circadian tolerance limits were first computed from the normotensive subjects as a function of trimester of pregnancy. The hyperbaric index and the percentage time of excess were then computed for each individual blood pressure series. The maximum hyperbaric index was below 15 mmHg X hour for normotensive pregnant women in all trimesters of pregnancy, and mostly above that value for women who subsequently developed gestational hypertension or preeclampsia. Sensitivity of the test based on the maximum hyperbaric index was 97% for women sampled during the first trimester of gestation, and increased up to 100% in the third trimester. The positive predictive value was 100% in all trimesters. Moreover, the computation of the hyperbaric index provided, on the average, an early identification of gestational hypertension or preeclampsia 20 weeks prior to the clinical confirmation of the disease. CONCLUSIONS: Ambulatory monitoring of blood pressure during gestation provides sensitive endpoints for use in early risk assessment and as a guide for establishing preventive interventions. The approach presented here represents a simple, reproducible, non-invasive, and highly sensitive test for the very early identification of gestational hypertension and preeclampsia.

Blood Pressure↗

Intracerebroventricular injection of dibutyryl cyclic adenosine 3',5'-monophosphate increases hypothalamic levels of neuropeptide Y.

This investigation examined in vivo the relationship between the nucleotide cAMP and hypothalamic levels of two peptides, neuropeptide Y (NPY) and galanin (GAL), which are known to potentiate feeding behavior. In brain-cannulated rats, third ventricular injections of N6,2'-O-dibutyryl cyclic adenosine 3',5'-monophosphate ((Bu)2cAMP, 25 micrograms), compared to saline, caused a significant increase in NPY levels in the arcuate nucleus (ARC) and medial parvocellular portion of the paraventricular nucleus (mPVN), while having no impact in other hypothalamic areas. These site-specific changes in NPY occurred in the absence of any alteration in circulating levels of insulin, corticosterone, aldosterone or glucose, or of changes in hypothalamic levels of GAL. These findings implicate cAMP as having regulatory functions within specific hypothalamic NPY-synthesizing neurons, projecting from the ARC to the mPVN, that are believed to be involved in energy homeostasis.

Aldosterone↗

Diurnal rhythm of galanin-like immunoreactivity in the paraventricular and suprachiasmatic nuclei and other hypothalamic areas.

The peptide galanin (GAL), when injected into the rat hypothalamus, is known to stimulate feeding behavior and affect the secretion of various hormones, including insulin and the adrenal steroid, corticosterone. To determine whether endogenous peptide levels shift in relation to natural rhythms of feeding and circulating hormone levels, rats were sacrificed at different times of the light/dark cycle, and their GAL levels were measured, via radioimmunoassay, in medial hypothalamic dissections and micropunched hypothalamic areas. The results suggest the existence of two distinct diurnal rhythms for hypothalamic GAL. One rhythm, detected exclusively in the area of the SCN, is characterized by bimodal peaks of GAL, threefold higher than basal peptide levels, around the onset of the dark and light periods. The second rhythm shows a single peak of GAL towards the middle of the nocturnal feeding cycle, specifically between the third and sixth hour. This latter rhythm is evident in the dorsal region of the medial hypothalamus, localized specifically to the lateral portion of the PVN. Moreover, it is inversely related to circulating insulin but unrelated to the adrenal steroids, suggesting a possible association between this pancreatic hormone and GAL in the PVN.

Aldosterone↗

High-cervical spinal cord electrical stimulation in brain low perfusion syndromes: experimental basis and preliminary clinical report.

Previous studies of our group showed that C1-C2 spinal cord stimulation increases carotid and brain blood flow in normal conditions in the goat and dog and it has a beneficial vasomotor effect in a model of vasospasm in the rat. For further clinical application it seemed rational to investigate the possible vascular changes mediated by this technique in experimental brain infarction. To this aim, 45 New Zealand rabbits were used. Brain infarction was produced by bilateral carotid ligation in 15, unilateral microcoagulation of the middle cerebral artery in 15 and by microcoagulation of the vertebral artery at the craniocervical junction in the other 15. One week later, following daily clinical scoring and cortical and posterior fossa blood flow readings by laser Doppler, a period of 120 min of right C1-C2 spinal cord electric stimulation was performed. A mean of 27% increase in previous blood flow recordings was obtained at the right hemisphere and a mean of 32% in the posterior fossa. This procedure was used in 10 patients presenting with various cerebral low perfusion syndromes. Though not constant, an increase in alertness, retention, speech, emotional lability and performance in skilled acts was achieved. No MR changes were observed, though SPECT readings showed an increase in blood flow in the penumbral perilesional area.

Adult↗

Neuropeptide Y in the arcuate nucleus is modulated by alterations in glucose utilization.

This study examined the response of hypothalamic neuropeptide Y (NPY) to specific metabolic challenges. After intraperitoneal administration of 2-deoxy-D-glucose, which blocks glucose utilization, NPY levels measured via radioimmunoassay were significantly potentiated in the arcuate (ARC) and suprachiasmatic nuclei of the rat hypothalamus. The antimetabolite mercaptoacetate, in contrast, which blocks fatty acid oxidation, produced no significant change and actually tended to reduce NPY levels in the ARC. It is concluded that glucose utilization, in particular, may constitute an important signal, either direct or indirect, in the modulation of NPY production in the hypothalamus.

Animals↗

[A new method to evaluate xerostomia in Sjögren's syndrome].

The extension of wetting in a standardized piece of filter paper was used to evaluate saliva output in 26 patients with Sjogren syndrome and 101 control subjects. The mean value for normals was 33.6 +/- 6.8 mm/5 min without significant differences for age and sex. Corresponding value for patients with Sjogren syndrome was 11.8 +/- 13.9 Accordingly, this is a simple and sensitive method to quantify xerostomia.

Adolescent↗