Biomedical subjects

S Valenzuela

Publications and source records attributed to S Valenzuela.

At least 19 recordsLinked to original sources

PubMed2006

Laterotrusive occlusal schemes and their effect on supra- and infrahyoid electromyographic activity.

The objective of this study was to determine the effects of canine guidance and group function on supra- and infrahyoid electromyographic (EMG) activity. The sample included 40 healthy subjects, 20 with bilateral canine guidance and 20 with bilateral group function. Surface electrodes were used to record the integrated EMG (IEMG) activity of the left supra- and infrahyoid muscles during (1) grinding from intercuspal position to lateral edge-to-edge contact position (with canine guidance or group function), (2) static clenching in edge-to-edge lateral contact position with canine guidance or group function, and (3) grinding from lateral edge-to-edge contact position (with canine guidance or group function) to intercuspal position. IEMG activity in the suprahyoid or infrahyoid muscles was not significantly different with canine guidance or group function. Supra- and infrahyoid IEMG activity in condition 2 was significantly higher than in condition 3, which was significantly higher than in condition 1. Supra- and infrahyoid IEMG activity was not significantly different with canine guidance and group function. Supra- and infrahyoid IEMG activity during the static recording (clenching) was significantly higher than during the dynamic recordings (grinding). Activity during grinding from the lateral edge-to-edge contact position to the intercuspal position was higher than vice versa.

Adolescent↗

PubMed2005

Breathing type and body position effects on sternocleidomastoid and suprahyoid EMG activity.

The objective of this study was to determine the effects of breathing type and body position on sternocleidomastoid and suprahyoid electromyographic (EMG) activity. The sample included 18 subjects with upper costal breathing type (study group) and 15 subjects with costo-diaphragmatic breathing type (control group). All individuals had natural dentition and bilateral molar support. EMG recordings at rest and while swallowing saliva were carried out by placing surface electrodes on the left sternocleidomastoid and left suprahyoid muscles. EMG activity was recorded while standing, seated upright, and in the lateral decubitus position. Upper costal breathing type subjects showed a significantly higher suprahyoid EMG activity at rest than costo-diaphragmatic subjects in all body positions studied (mixed model with unstructured covariance matrix). In the lateral decubitus position, both breathing types showed a significantly higher sternocleidomastoid EMG activity at rest and while swallowing saliva. The suprahyoid muscles demonstrated a significantly higher EMG activity at rest as well as in the lateral decubitus position (mixed model with unstructured covariance matrix). These results are relevant because sternocleidomastoid and suprahyoid muscles play an important role in controlling the head posture and mandible dynamics. The neurophysiological mechanisms involved are discussed.

Adult↗

PubMed2000

Effects of head and neck inclination on bilateral sternocleidomastoid EMG activity in healthy subjects and in patients with myogenic cranio-cervical-mandibular dysfunction.

This study was conducted in order to determine the effect of head and neck position on bilateral electromyographic (EMG) activity of the sternocleidomastoid muscles. The study was performed on 16 patients with myogenic cranio-cervical-mandibular dysfunction (CMD) and 16 healthy subjects. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the right and left sternocleidomastoid muscles. EMG activity was recorded in the left lateral decubitus position, in a darkened room and with the individual's eyes closed, under the following experimental conditions: 1. Head, neck, and body horizontally aligned; 2. Head and neck upwardly inclined with respect to the body, simulating the effect of a thick pillow, 3. Head and neck downwardly inclined with respect to the body, simulating the effect of a thin pillow. Variation of head and neck positions was determined by measuring the distance from the angle of neck and shoulder and the apex of the shoulder (SND = shoulder-neck distance) of each individual. Then, head and neck were forward or downwardly inclined with respect to the body at one-third of SND. A significantly higher contralateral EMG activity and a more asymmetric EMG activity were observed in the CMD group than in the healthy subjects (Kruskal-Wallis Test). These results suggest a different behavior of bilateral sternocleidomastoid EMG activity in CMD patients than in healthy subjects depending on the positioning of the head and neck.

Adult↗

PubMed2000

Comparative study between children with and without cleft lip and cleft palate, part 2: electromyographic analysis.

OBJECTIVE: This study was conducted to compare electromyographic (EMG) activity of superior orbicularis oris muscle between children with repaired cleft lip and cleft palate and children without clefts. METHODS: This study included 28 children with mixed dentition. They were divided into two groups. The study group included 14 children with repaired unilateral cleft lip and cleft palate, ranging in age from 6 to 12 years, who presented clinically with a short upper lip, abnormal lip seal, and inhibition of sagittal development of the midface as assessed radiographically. The control group included 14 children without clefts ranging in age from 8 to 11 years. All had normal lip seal, nasal breathing, and a clinically normal body posture. DESIGN: Bipolar surface electrodes were used for EMG recordings of resting level activity and during swallowing of saliva, speech, and chewing and swallowing of an apple. RESULTS AND CONCLUSIONS: A significantly higher level of activity at rest and during swallowing of saliva was observed in the cleft lip and cleft palate group. Similar activity during speech and chewing and swallowing of an apple was observed in both groups. The higher level of activity at rest and during swallowing of saliva in children with cleft lip and cleft palate seems to suggest that upon higher functional demands their activity increases less than in children without clefts. From a clinical point of view, if increased EMG activity at rest and during swallowing of saliva reflects increased force on the maxilla, then our findings may corroborate Bardach's findings (1990) that surgical treatment of cleft lip has an iatrogenic effect on facial growth, although the lack of significant correlation between the cephalometric data and EMG findings in the present study.

Child↗

PubMed1999

Pediatric neuroendoscopy in Chile. Analysis of the first 100 cases.

The personal series of the first 100 cases of neuroendoscopy performed at the Pediatric Neurosurgery Service of the Institute of Neurosurgery Alfonso Asenjo in Santiago-Chile is presented. The patients were the first to undergo endoscopic operations for different types of hydrocephalus and their ages ranged from newborn up to 15 years. Their clinical records, surgical protocols, radiologic results, videos and follow-up are reviewed. A mortality of 2% and a morbidity of 7% were found in this group, hemorrhage, ventriculitis and CSF leakage being the main problems. Success was achieved in more than 75% of cases in the whole series. If we only consider the group of III ventriculostomies performed in noncommunicating hydrocephalus, our success rate rises to 90%. Follow-up ranges from 30 months in the first case to 2 months in the last case considered. All patients were operated on by the author using a rigid Gaab scope with 5.8 mm OD coupled to a Codman light source and a microcamera. Surgical technique was always the same using a right precoronal burr hole. Prophylaxis with vancomycin was indicated in all cases. General, partial and specific results are presented and allow the conclusion that this is an excellent procedure when it is well indicated. It means a great saving in shunts and treatments and has become an alternative to shunts in all neurosurgical units.

Adolescent↗

PubMed1999

Body position effects on EMG activity of the temporal and suprahyoid muscles in healthy subjects and in patients with myogenic cranio-cervical-mandibular dysfunction.

This study was conducted in order to determine the effects of body position on integrated electromyographic (IEMG) activity of anterior temporal and suprahyoid muscles. The study was performed on 15 patients with myogenic cranio-cervical-mandibular dysfunction (CMD) and 15 healthy subjects. IEMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the anterior temporal and suprahyoid muscles in the following body positions: standing, seated, supine, and lateral decubitus position. Insignificant changes in IEMG activity of both muscles were observed upon variations in the body position. Insignificant differences in IEMG activity were observed between patients with myogenic CMD and healthy subjects. A pattern of higher IEMG at rest and during swallowing of saliva was observed in the suprahyoid muscles than in the anterior temporal muscles, whereas during maximal clenching activity, an opposite pattern was observed. Results of the present study seem to suggest that for the anterior temporal and suprahyoid muscles there is no specific body position that could be relevant to initiate and/or to perpetuate a craniomandibular dysfunction.

Adult↗

PubMed1999

Effects of two types of pillows on bilateral sternocleidomastoid EMG activity in healthy subjects and in patients with myogenic cranio-cervical-mandibular dysfunction.

This study was conducted in order to determine the effects of two types of pillows on bilateral electromyographic (EMG) activity of the sternocleidomastoid muscles. The study was performed on 15 patients with myogenic cranio-cervical mandibular dysfunction (CMD) and 15 healthy subjects. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the right and left sternocleidomastoid muscles. EMG activity was recorded in the supine position and in the lateral decubitus position (according to each individual's normal resting habit), with their eyes closed and with the head supported by means of: 1. a Sleep Easy Pillow (Interwood Marketing Groups, Concord, Ontario, Canada) and 2. a Standard Pillow (INDUVET). In the lateral decubitus position a significantly higher contralateral than ipsilateral EMG activity at rest in the sternocleidomastoid muscles was observed with both types of pillows in all the sample studied (ANOVA and Duncan's Multiple-Range Test). Asymmetrical bilateral EMG activity in the lateral decubitus position with both types of pillows in healthy subjects and in patients with myogenic CMD, suggests that if this body posture is prolonged, it could be important in the genesis of sternocleidomastoid hyperactivity.

Adult↗

PubMed1998

Body position effects on EMG activity of sternocleidomastoid and masseter muscles in healthy subjects.

This study was conducted in order to determine the effects of body position on integrated electromyographic (IEMG) activity of sternocleidomastoid and masseter muscles in 20 healthy subjects. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the sternocleidomastoid and masseter muscles (contralateral to the habitual side of sleeping of each subject), in the following body positions: standing, seated, supine, and lateral decubitus position. Significant higher EMG activities were recorded in the sternocleidomastoid muscle in the lateral decubitus position, whereas significant lower EMG activities were recorded in the masseter muscle in the supine position. This finding supports the idea that there may exist a differential modulation of the motor neuron pools of the sternocleidomastoid and masseter muscles of peripheral and/or central origin. Significant differences in the EMG pattern as well as in the levels of EMG activities upon variations in body positions were observed between healthy subjects and patients with myogenic craniomandibular dysfunction reported by Palazzi, et al.

Adolescent↗

PubMed1998

Visual input effect on EMG activity of sternocleidomastoid and masseter muscles in healthy subjects and in patients with myogenic cranio-cervical-mandibular dysfunction.

This study was conducted in order to determine the input visual effect on electromyographic (EMG) activity of the sternocleidomastoid and masseter muscles in the supine and lateral decubitus positions. The study was performed on 22 patients with myogenic cranio-cervical-mandibular dysfunction (CMD) and 18 healthy subjects. EMG activity at rest and during swallowing of saliva and maximal voluntary clenching was recorded in the supine and lateral decubitus positions in the following conditions: 1. with eyes open; and 2. with eyes closed after 5 minutes in a dark room. A significant decrease of EMG activity at rest with closed eyes in both groups was observed in the sternocleidomastoid (lateral decubitus position) and in the masseter muscle (supine position). During swallowing of saliva a significant decrease of EMG activity with closed eyes was observed only in the sternocleidomastoid muscle (lateral decubitus position) in healthy subjects. During maximal voluntary clenching any significant differences were observed upon variation in the visual input. The significant change in EMG activity, mainly observed at rest, suggests that the visual input effect is weak. The absence of a significant change in EMG activity during maximal voluntary clenching upon variation in the visual input could be clinically relevant in patients with myogenic CMD who habitually brux.

Adolescent↗

PubMed1996

[Systemic leptospirosis as a cause of multiple organ failure. Report of a case].

Leptospirosis is a world-spread zoonosis that is incidentally acquired by humans. It causes a diphasic febrile illness in which the Weil syndrome is its severest form, with renal, hepatic, clotting and central nervous system involvement. We report a 73 years old male, that was admitted to an intensive care unit with multiple organ failure due to leptospirosis. The clinical picture initially resembled a sepsis due to biliary tract obstruction and was operated, not finding a biliary tract obstruction. Considering the history of a fall to sewed waters, leptospirosis was suspected and treatment with penicillin was started, obtaining a full recovery of the patient.

Abdominal Pain↗

PubMed1995

[Self esteem, affectivity perception, aims, and risk behaviors among teenagers of both sexes].

A self applied and anonymous enquiry was answered by 948 teenagers (600 female), participating in an integral health education plan and coming from a school located in a low income community of Metropolitan Santiago. Twenty nine percent came from single or foster parent families and 18.4% of parents were separated. Nineteen percent of women and 9.8% of men felt that they were not loved by their parents; 30.5% of women and classified as bad or regular their relationship with their fathers and 22.1% of men similarly classified their relationship with their mothers. Eighteen percent of men and 16.5% of women ignored their parent's educational level. Ten to 24% had a negative self image and 50% were unsure about their study goals. Forty eight percent of men and 25.5% of women had get drunk; 24.1 and 12.8% had smoked marihuana. Half of the sample manifested attraction to dangerous situations; 22% had participated in quarrels and 34% had attacked other people. Twenty three percent of men and 35% of women had considered committing suicide. It is concluded that the lack of affection, a deteriorated self image, difficult parental relationships and orientation toward violence appear as the main problems in this sample of teenagers.

Adolescent↗

PubMed1995

[Reproductive health in adolescent students: knowledge, attitudes, and behavior in both sexes, in a community of Santiago].

Nine hundred forty eight teenagers (600 females) from a public school of one of the poorest communities of Santiago were surveyed about knowledge and practices on sexuality and reproductive health. Twenty four percent of females and 40% of males did not talk about their problems at home, instead they talked preferentially with their friends. Half of the sample attributed a risk a pregnancy to the first sexual intercourse; 67% did not know the infertile phase of the menstrual cycle and 20% did not identify two sexually transmitted diseases. Sixty percent considered rhythm technique as a safe fertility control method, 60% of males and 50% of females considered masturbation as risky, 57% of males and 49% of females estimated that condoms could be reused and between 5 and 16% of the sample correctly identified AIDS modes of transmission. Fifty percent had a couple and 23% of males and 17% of females had a sexual intercourse in the last six months; of these, 45% of women and 27% of men used a contraceptive method. Four percent of women and 6% of men became involved in a pregnancy and 57% of these terminated in abortions. It is concluded that knowledge about sexuality and reproductive biology among low income teenagers is scanty.

Adolescent↗

PubMed1994

Literature review: sinus pericranii.

Sinus pericranii is a rare circumscribed fluctuating vascular swelling of the scalp that communicates with the intracranial venous system. It has been associated with other intracranial vascular malformations. The tumour is usually round, fluctuant, nonpulsatile, and disappears with compression. Its size increases during manoeuvers that increase the intracranial pressure. Approximately 100 cases were reported in the literature. The antecedents, different surgical procedures, differential diagnoses, and associated malformations were reviewed.

Adolescent↗

PubMed1993

Function of rotavirus VP3 polypeptide in viral morphogenesis.

The phenotype of the rotavirus SA-11 mutant tsB carrying a thermosensitive mutation in gene 3, which encodes VP3, was characterized further from both infected cells and purified viral particles. The mutant phenotype was initially identified as negative for in vivo double- and single-stranded RNA synthesis. Our results show that the in vitro transcriptional properties of the tsB mutant at the restrictive temperature were identical to those of the wild-type strain. Similar results were obtained with respect to the VP3-associated guanylyl-transferase activity. Analysis of viral particles made by mutant-infected cells at the restrictive temperature showed that only empty single-shelled particles were assembled. This indicates that viral morphogenesis is halted after the initial viral transcription and before RNA replication, suggesting that VP3 may be required as part of the replicase system but not for subviral particle assembly. These data suggest that such a phenotype is not due to alteration of a VP3 function related to transcription.

Capsid↗

PubMed1992

Respiratory syncytial virus detection by dot blot hybridization with a nonradioactive synthetic oligo deoxynucleotide probe.

A synthetic oligodeoxynucleotide corresponding to a region of the nucleocapside gene (N) of respiratory syncytial virus (RSV), was used as a DNA probe to develop a nonradioactive hybridization assay for the detection of RSV. The probe was labeled by incorporation of biotin-7-dATP to the 3' end by a reaction catalyzed by terminal deoxynucleotydil transferase. The dot blot hybridization assay was found to be specific for RSV when tested against RSV isolates (subgroups A and B) obtained from cell cultures and isolates of adenovirus, reovirus, rotavirus, and pararotavirus. The assay detected both RSV subgroups (A and B) without significant differences. The dot blot hybridization assay using the nonradioactive probe led to similar results to indirect immunofluorescence (IFI) when tested against a panel of 64 clinical samples from nasopharyngeal secretions of infants with clinical symptoms of respiratory disease. This assay may provide the basis for a rapid, simple, and inexpensive method for routine RSV diagnosis.

Base Sequence↗

PubMed1992

[Giant cholesterol cysts of the petrous apex].

In connection with their two own cases, the authors deal about the giant cholesterol cysts of the petrous apex. The lesions which are to be differentiated from epidermoid cysts are cholesterol granulomas. Their petrous apex location explains their characteristic large appearance. As each cholesterol granuloma, they occur when a bony cell is obstructed. This chronic obstruction induces mucosal edema then bleedings which lead to the formation and, by the lack of drainage, to the accumulation of cholesterol crystals. These crystals initiate a non specific reaction to foreign bodies, a granuloma, which also can bleed. Thus, a continuous cycle perpetuates the growth of the lesion. This lesion, when it is localized in the petrous apex, can reach a big size before the appearance of some signs. Usually, these are otologic (sensorineural hearing loss, tinnitus, vertigo) and/or cranial nerve palsies (V, VI, VII). C.T. scan (well defined, sharply marginated bony expansible lesion with isodense to the brain central part) and M.R.I. (central region of increased intensity on both T1 and T2 weighted images and peripheral rim of markedly decreased signal intensity in all instances) features are characteristic enough to allow diagnose with other petrous apex lesions (cholesteatoma, mucocele, epithelial cyst, histiocytosis X, ...). Surgical treatment must try to evacuate and to aerate the cavity or perhaps to obliterate it with fatty pieces in order to prevent the recurrence.

Adult↗

PubMed1992

Ménière's syndrome and allergy.

The role of allergic and autoimmune factors in both the production and amplification of symptoms of Ménière's disease has yet to be clearly defined. Reasons to suspect an allergic factor influencing Ménière's disease include a relationship with symptoms to seasons or a suspect food, a known history of allergy in a Ménière's patient, bilaterality of symptoms, and refractoriness to the usual medical and surgical treatments. The majority of patients tested in this study were found to have rather low levels of sensitivity to inhalant allergens as measured by SET, and to have food reactions to very common "hidden" foods that are frequently ingested in the diet. By proper recognition and treatment of the underlying allergic factors affecting Ménière's disease, significant clinical improvement may be obtained even in longstanding or refractory cases.

Adult↗

PubMed1991

Photoaffinity labeling of rotavirus VP1 with 8-azido-ATP: identification of the viral RNA polymerase.

Rotavirus single-shelled particles have several enzymatic activities that are involved with the synthesis of capped mRNAs both in vivo and in vitro. Because single-shelled particles must be structurally intact to carry out transcription, it has proven to be difficult to identify the protein within such particles that possesses associated RNA polymerase activity. One approach for characterizing the function of the individual proteins within single-shelled particles is to use nucleotide analogs to specifically label those proteins, such as the viral RNA polymerase, that have affinity for nucleotides. In this study, 8-azido-ATP (azido-ATP), a photoreactable nucleotide analog, was used to identify the viral RNA polymerase on the basis of the ability of the analog to inhibit transcription activity associated with rotavirus particles on exposure to UV light. When single-shelled particles were treated with UV light in the presence of [alpha-32P]azido-ATP, the structural protein VP1 became radiolabeled because of cross-linking of the nucleotide analog, and there was a corresponding decrease in the ability of the particles to synthesize mRNA. In parallel experiments in which single-shelled particles were not exposed to UV light, VP1 was not radiolabeled and the particles successfully used azido-ATP as a substrate for the synthesis of viral mRNAs. Taken together, these results are consistent only with the conclusion that VP1 is the rotavirus RNA-dependent RNA polymerase.

Adenosine Triphosphate↗