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Biomedical subjects

C Suárez

Publications and source records attributed to C Suárez.

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

Tumours of the posterior pharyngeal wall: the use of the platysma flap.

Posterior pharyngeal will tumours are infrequent neoplasms with a very poor prognosis. The 5 year survival rate range from 3% to 32%. Most authors agree that the treatment of choice is surgery with post-operative radiotherapy. The results of treatment of 36 patients (tumour excision plus bilateral neck dissection and post-operative radiotherapy) in which the posterior pharyngeal wall defect was closed with a platysma myocutaneous flap were compared with other forms of repair (13 patients). The 5 year survival rate was 17.2% in the whole group. Laryngeal voice was achieved in 79% of patients having a platysma flap reconstruction. The platysma myocutaneous flap is very satisfactory for the repair of the posterior pharyngeal wall as it is easy to perform, it is oncologically safe and its functional results match well with other forms of reconstruction, with the advantage of laryngeal preservation.

Actuarial Analysis↗
PubMed1997

Deletion and methylation of the tumour suppressor gene p16/CDKN2 in primary head and neck squamous cell carcinoma.

AIMS: To study the homozygous deletion and methylation status of the 5' CpG island of the p16 and p15 genes (9p21) in a set of primary advanced head and neck squamous cell carcinomas (SCC) and to test whether inactivation of these genes by these mechanisms contributes to head and neck SCC development. METHODS: DNA was extracted from fresh tumours. Homozygous deletion was determined by the polymerase chain reaction (PCR) followed by hybridisation with the corresponding probe, radioactively labelled by the random priming method. Methylation status of the CpG island of the 5' region of these genes was assessed by digestion with the appropriate restriction enzymes followed by PCR and subsequent hybridisation with the corresponding probe. The presence of point mutations was determined by PCR-SSCP (single strand conformation polymorphism). RESULTS: The p16 and p15 genes were homozygously deleted in 20% and 10% of the tumours, respectively. No point mutations were found at p16 and p15. The 5' CpG island at the p16 gene was methylated in 20% of the cases. CONCLUSIONS: The tumour suppressor gene p16 is inactivated through homozygous deletion or methylation in a significant proportion of cases of head and neck SCC.

Carcinoma, Squamous Cell↗
PubMed1996

MYC amplification in squamous cell carcinomas of the head and neck.

OBJECTIVES: To establish the frequency of MYC amplification in squamous cell carcinoma (SCC) of the head and neck to evaluate its correlation with clinicopathologic variables that are used in clinical practice. DESIGN: Cohort analytic study. SETTING: University Hospital. PATIENTS: Fifty-nine consecutive patients with SCC of the head and neck. INTERVENTION: Oncologic surgery. MAIN OUTCOME MEASURES: The MYC copy number in tumor samples was estimated with the polymerase chain reaction. The presence or absence of amplification was correlated with the anatomic site, T stage, nodal involvement, pathologic grade, recurrence, distant metastases, and survival. RESULTS: Six SCC specimens (11%) showed MYC amplification. A highly statistical correlation between MYC amplification and T stage was noted (P < .005). Amplification was also significantly correlated with a hypopharyngeal primary site (P < .05). No correlation among amplification status, nodal involvement, pathologic grade, relapse, metastases, and survival was observed. CONCLUSIONS: Amplification of MYC is associated with advanced primary tumors, and it appears to be a late event in the tumorigenesis of SCCS of the head and neck. However, there is no correlation between MYC amplification and prognosis.

Adult↗
PubMed1996

Detection of p53 protein in oropharyngeal carcinoma. Prognostic implications.

OBJECTIVE: To demonstrate how the detection of p53 protein in formaldehyde-fixed, paraffin-embedded oropharyngeal carcinoma may be used as a factor in estimating prognosis. SETTING: University medical centers. DESIGN: Validation cohort. Formaldehyde-fixed, paraffin-embedded squamous cell carcinoma of the oropharynx tissues from 106 patients who underwent surgical therapy between 1975 and 1988 were immunostained by using M-7001 antibody (IgG class). RESULTS: Overexpression of p53 was observed in 46 tumors (43.4%). The detection of nuclear p53 was significantly associated with an increased risk of recurrence of oropharyngeal carcinoma (P = .05). Similar results were obtained when the presence or absence of p53 in the nuclei of the tumor cells was studied in relation to overall survival (P < .001). In a multivariate analysis stratified according to grade, pathological stage, and lymph node status, nuclear p53 status was an independent predictor of overall survival (P < .001). CONCLUSIONS: In patients with squamous cell carcinoma of the oropharynx, an accumulation of p53 in the tumor cell nuclei detected by immunohistochemical methods predicts a significantly increased risk of death, independent of tumor grade, stage, and lymph node status. The p53 overexpression appears to be a useful prognostic factor.

Adult↗
PubMed1996

Time-resolved observations of shock waves and cavitation bubbles generated by femtosecond laser pulses in corneal tissue and water.

BACKGROUND AND OBJECTIVE: Photodisruption in ocular media with high power pulsed lasers working at non-absorbing frequencies have become a well established surgical tool since the late seventies. Shock waves and cavitation bubbles generated by the optical breakdown may strongly influence the surgical effect of photodisruptive lasers. We have investigated the shock wave and cavitation bubble effects of femtosecond laser pulses generated during photodisruption in corneal tissue and water. The results are compared to those obtained with longer laser pulses. STUDY DESIGN/MATERIALS AND METHODS: Laser pulses with 150 fs duration at approximately 620 nm wavelength have been focused into corneal tissue and water to create optical breakdown. Time-resolved flash photography has been used to investigate the dynamics of the generated shock waves and cavitation bubbles. RESULTS: A rapid decay of the shock waves is observed in both materials with similar temporal characteristics and with a spatial range considerably smaller than that of shock waves induced by picosecond (or nanosecond) optical breakdown. Cavitation bubbles are observed to develop more rapidly and to reach smaller maximum diameter than those generated by longer pulses. In corneal tissue, single intrastromal cavitation bubbles generated by femtosecond pulses disappear within a few tens of seconds, notably faster than cavitation bubbles generated by picosecond pulses. CONCLUSIONS: The reduced shock wave and cavitation bubble effects of the femtosecond laser result in more localized tissue damage. Therefore, a more confined surgical effect should be expected from a femtosecond laser than that from picosecond (or nanosecond) lasers. This indicates a potential benefit from the applications of femtosecond laser technology to intraocular microsurgery.

Absorption↗
PubMed1996

Rostrocaudal and ventrodorsal change in neuronal cell size in human medial vestibular nucleus.

BACKGROUND: The present paper describes the cytoarchitectonic, morphometric, and three-dimensional characteristics of the human medial vestibular nucleus (MVN). We also studied the regional distribution, in size, of the different neurons and its possible relationship with a functional polarization of the different regions of the nucleus. METHODS: Nine adult human brainstems (30-50 years of age) without neurological problems were used. Specimens were obtained from necropsy and fixed in 4% paraformaldehyde and 5% acetic acid in distilled water. After fixation, blocks were washed, dehydrated, and embedded in paraffin and serial sectioned at 20 microns. Sections were stained with formaldehydethionin, dehydrated, cleared in eucalyptol, and mounted with Eukitt. MVN neurons were drawn with the aid of a camera lucida at 200-micron intervals at 390 x magnification. Serial 50-micron frozen sections were used to determine the volume of the MVN. The three-dimensional reconstruction of MVN was accomplished with a drawing program in a Macinthosh II computer and an AVS on a Stardent workstation computer. RESULTS: In the three-dimensional reconstruction, the human MVN shows a pyramidal form. The base of this pyramid constitutes the rostral limit, and its vertex forms the caudal border of the MVN. The estimated volume is 30.44 +/- 0.85 mm3, with a neuronal population of 127,737 cells and 4,136 neurons/mm3 in density. The average neuronal cross-section changes from one minimum at caudal level (212.46 +/- 2.04 microns 2) to one maximum at rostral level (491.47 +/- 5.08 microns 2). Four cell types, small (< 200 microns 2), medium (200-500 microns 2), large (500-1000 microns 2), and giant (> 1,000 microns 2) cells, were observed. Medium cells constitute 66%, small cells 18%, and large and giant cells 15% and 1% of the neuronal population. CONCLUSIONS: The MVN shows a variation in neuronal size, and it has the highest neuronal density of all the human vestibular nuclei. Large cells predominate in rostral regions of the MVN, with significant differences in the area and diameter of the cells among rostral, central, and caudal regions. Furthermore, the largest cells are grouped in the ventrolateral part of the nucleus, close to its boundaries with the inferior and the lateral vestibular nuclei. The morphological polarization, with respect to the neuronal size of the MVN, can be related to a functional polarization of rostral and caudal regions of this nucleus.

Adult↗
PubMed1996

Amplification of ERBB oncogenes in squamous cell carcinomas of the head and neck.

The activation of ERBB oncogenes has been described in various human tumours, including squamous cell carcinomas of the head and neck (SCCHN), and, in some of them, it has been correlated with a poor prognosis. Tissue samples from 59 patients with SCCHN were studied. After DNA extraction, the ERBB1, ERBB2 and ERBB3 copy number in tumour samples was estimated with the polymerase chain reaction (PCR) method. The PCR products were analysed by agarose gel electrophoresis and quantified by image analysis techniques. 9 (15%) cases presented with ERBB1 amplification, which was correlated with lymph node involvement (P = 0.04), poorly differentiated tumours (P = 0.03) and a hypopharyngeal primary site (P = 0.035). No correlation among amplification status, recurrence, metastases and survival was observed, although this may be due to the small number of patients in the amplified group. None of the 59 cases presented amplification of ERBB2 and ERBB3 oncogenes.

Adult↗
PubMed1996

Castleman's disease restricted to the infratemporal fossa.

Giant lymph node hyperplasia (Castleman's disease) is usually reported as a solitary mediastinal tumour, although involvement of other anatomical sites and a multicentric form have been reported. We describe a rare case of Castleman's disease due to its localisation (the left infratemporal fossa) and histology (plasma-cell variant). A brief review of the main clinico-histological characteristics of Castleman's disease is also presented.

Brain↗
PubMed1996

Cerebrospinal fluid tyrosine and 3,4-dihydroxyphenylacetic acid levels in migraine patients.

We studied biochemical parameters related with central dopaminergic neurotransmission in migraine patients during crisis. We determined tyrosine and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in cerebrospinal fluid (CSF) of 47 patients, 29 suffering migraine without aura and 18 suffering migraine with aura, comparing them with 27 control subjects. Tyrosine levels did not differ significantly between patients and controls. The CSF concentration of DOPAC was 0.73 +/- 0.55 ng/ml in the control population, 3.84 +/- 2.08 ng/ml in patients with migraine without aura and 3.30 +/- 1.49 ng/ml in patients suffering migraine with aura. The concentration of DOPAC correlated positively with the intensity of headache. These results suggest that patients with migraine have a central dopaminergic hyperfunction, probably related to a coexisting central dysfunction of noradrenergic neurotransmission.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1996

[The prognostic value of analytical hemorheological factors in stroke].

Plasmatic hyperviscosity is a known vascular risk factor which depends, among other parameters, upon total proteins, haematocrit value and fibrinogen. The aim of this study was to determine the relationship between these analytical haemorrological parameters and mortality and acute stroke sickness rate. We studied 216 patients with brain infarct and spontaneous intracerebral haemorrhage out of a sample of 256 acute stroke patients. We evaluated neurological affectation using the Canadian scale upon admission, on the seventh day and after three months. We determined plasmatic haemorrological factors (haematocrit, fibrinogen and total proteins) upon admission and again after one week and then at three months High fibrinogen levels in plasma were related to brain infarct mortality regardless of the cause of death.

Adult↗
PubMed1995

Supraglottic laryngectomy with or without postoperative radiotherapy in supraglottic carcinomas.

A retrospective review of 193 previously untreated patients with primary supraglottic carcinoma was undertaken to ascertain the efficacy of postoperative radiotherapy. All the patients received a supraglottic laryngectomy, and patients received a total of 284 elective or therapeutic neck dissections. Ninety-four (48.7%) of the patients received postoperative radiotherapy. The incidence of local recurrence was 8.2% but the recurrence rate was unrelated to the use of postoperative radiotherapy. Neck recurrence was observed in 12.9% of patients, with no influence of postoperative radiotherapy in the dissected neck. The incidence of locoregional recurrences by stage in irradiated and nonirradiated patients did not reach significant difference. The 3-year survival was 74.3%. The overall survival of the whole series and by stage was not statistically altered in combined therapy compared to surgery.

Adult↗