PubMed Health⌕ Search

Biomedical subjects

A Poblano

Publications and source records attributed to A Poblano.

16 recordsLinked to original sources
PubMed1997

[Auditory provoked potentials in children with neonatal risk for hypoacusia].

Auditory evoked potentials of the brain stem (AEPBS) provide a simple noninvasive method of evaluating hearing function and have been widely used for early detection of hypoacusis in children. Between April 1992 and May 1994, a study was done of 400 Mexican children who presented at least one neonatal risk factor for hearing impairment. The average age of the children studied was 6.6 months and their average gestational age at birth was 35.1 weeks. Just over half of them (51%) had been treated with amikacin. The study found 1427 risk factors (3.5 per child), the most common ones being exposure to ototoxic substances, hyperbilirubinemia, and birthweight of less that 1500 g. In 27% of the children, peripheral auditory changes were found, and 13% did not respond to auditory stimuli. Low birthweight and young gestational age at birth, high serum concentration of bilirubin, sepsis, subependymal or intraventricular hemorrhage, mechanical ventilation, and exposure to ototoxic substances were significantly associated with the presence of severe or profound hypoacusis.

Child↗
PubMed1996

Electro-oculographic recordings reveal reading deficiencies in learning disabled children.

This study was undertaken in order to learn the functional differences in reading tasks between two groups of children: those identified as learning disabled and a group of control children. During the earliest stages of learning to read, children adopt a logographic strategy, in which letter order is ignored and phonologic factors are secondary. The children later move into an alphabetic and then to an orthographic reading stage. Reading strategies can be studied by electro-oculographic (EOG) recordings during text reading. This investigation uses EOG to study text reading time, and number of saccadic and regressive movements, to test if learning disabled children show altered strategies on text reading. Nineteen learning disabled and thirteen control subjects were included in the study. Learning disabled children showed longer text reading time, and greater number of saccadic and regressive eye movements. Electro-oculographic recording is not a test customarily performed on learning disabled children. However, our results concerning the dynamic discriminative reading have shown that it can be a useful tool for the examination of learning disabled children.

Child↗
PubMed1996

Pattern-visual evoked potentials in thinner abusers.

Organic solvents cause injury to lipids of neuronal and glial membranes. A well known characteristic of workers exposed to thinner is optic neuropathy. We decided to look for neurophysiologic signs of visual damage in patients identified as thinner abusers. Pattern reversal visual evoked potentials was performed on 34 thinner abuser patients and 30 controls. P-100 wave latency was found to be longer on abuser than control subjects. Results show the possibility of central alterations on thinner abusers despite absence of clinical symptoms.

Administration, Inhalation↗
PubMed1994

Prenatal and perinatal low level lead exposure alters brainstem auditory evoked responses in infants.

Wave III latency and the III-V interpeak interval of brainstem auditory evoked responses in infants in the first weeks of life decreased and increased, respectively, in association with mid-pregnancy maternal blood lead levels (2.5-35 micrograms/dl) in a group of 30 prospectively followed healthy pregnancies and deliveries. The rapid myelination of brainstem auditory pathways occurring around mid-pregnancy and the lengthening of the III-V interpeak interval with increased mid-pregnancy maternal lead suggest that brain structures involved in spatial localization of sound may be compromised by prenatal lead exposure. The data also indicate that maternal blood lead measurements during pregnancy provide an adequate surrogate index of fetal exposure.

Adult↗
PubMed1993

[Brainstem auditory evoked potentials in low and high risk newborns].

Brainstem auditory evoked potentials (BAEP) were performed in a population of preterm infants of 32-34, 35-37 and 38-41 weeks of gestational age (GE) high risk newborns, and in 38-41 weeks GE low risk newborns. Statistical differences were found between both 38-41 weeks GE groups. High risk newborns showed longer latencies of waves III and V (P < 0.001), and I-III and I-V interwave intervals (P < 0.01). Our data show that auditory brainstem system suffer in high risk newborns. Results is discussed in relationship with other brainstem auditory evoked potentials studies in high risk newborns due it's clinical implications of present data.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1992

Recovery of vestibular function in young guinea pigs after streptomycin treatment. Glutamate decarboxylase activity and nystagmus response assessment.

Fifty-day streptomycin (STP) treatment in guinea pigs causes specific vestibular hair cell (VHC) types I and II (HCI; HCII) degeneration, depletion of glutamate decarboxylase (GAD) and a gradual disappearance of postrotatory nystagmus response (PRNR), which is a sign of vestibular function alteration. In order to look for a possible spontaneous reversibility and its time course guinea pigs receiving 300 mg/kg STP daily were monitored for PRNR and vestibular GAD loss. Once PRNR was lost, STP was interrupted and the animal was allowed to recover; at the time that PRNR was completely reestablished, vestibular GAD was measured. PRNR was lost within 22-25 days of STP treatment. Vestibular GAD showed a loss that, with time of treatment, gave two slopes: a fast decrement (45% in 20 days) and a slow one (40% in the remaining 30). Stopping of the STP treatment after 22-25 days and animal recovery resulted in the return of both PRNR and GAD activity 22 days after STP stoppage. These results suggest two STP-susceptible GAD-containing VHC populations, one more sensitive than the other, possibly HCI followed by hair cell II (HCII). As hypothetic HCI loss and PRNR disappearance is simultaneous, the important role of the former for vestibular function could be inferred. Interruption of STP treatment after PRNR loss results in a long range restoration of both GAD activity and vestibular function, and thus recovery of HCI, the first evidence of its occurrence in a mammalian vestibule, could be suggested. The intimate mechanism of this recovery remains to be seen.

Animals↗
PubMed1991

[Brain-stem auditory evoked potentials and median latency in children with Down's syndrome].

We studied 20 milliseconds of the brainstem auditory evoked responses and 50 milliseconds of the middle latency responses in 11 children with Down's syndrome, between 6-9 years of age. The results were compared with those from 10 control children. We found a significative reduction of the amplitude of waves I, III, V in the former group. Central transmission time was shortest and frequently wave Pa was absent in patients with Down's syndrome patients. We hypothesized that the abnormalities of amplitude of the evoked responses may be related to presence of less neurons in the brain of patients with Down's syndrome. The reduction of central transmission time may be related to presence of microcephalia and significantly accelerated rates of action potential depolarization, repolarization and decreased spike duration. Wave Pa may have been absent due to microgyria of Heschl's temporal gyrus previously reported in patients with Down's syndrome.

Acoustic Stimulation↗
PubMed1991

[Auditory brain stem evoked potentials of average latency in dyslexics and controls].

The goal of this paper was to study the auditory pathway of nine controls and nine pure dyslexic subjects using brainstem auditory evoked responses and middle latency responses. We found no differences in latency and amplitude between both groups; only a small difference in the V right/V left relation in favour of the right V wave in controls and left V wave in dyslexics. This findings is discussed in relation to cerebral dominance.

Acoustic Stimulation↗
PubMedDate not supplied

Prenatal and perinatal lead exposures alter acoustic cry parameters of neonate.

We performed acoustic analyses on cries elicited from a subset of healthy babies born to the Mexico City Prospective Lead Study at 2 days (n = 75), 15 days (n = 176), and 30 days (n = 166). Lead was measured in maternal blood every 8 weeks during pregnancy from week 12 to delivery and in umbilical cord (1-38 micrograms/dL, 0.05-1.84 mumol/L). Percent nasalization and number of cries decreased in babies born to mothers with higher lead levels in the last two trimesters while median fundamental frequency increased in babies born to mothers with higher lead at 12 weeks of pregnancy, and with higher cord lead in multiple regression analysis. Decreased percent nasalization was related to increased brainstem auditory evoked response latencies and interpeak intervals in a subset of the sample. The results suggest an effect of gestational exposure to lead on apparatus innervated by cranial nerves and/or lead effect on cry mediated by lead-altered auditory function. Altered baby cry and auditory function associated with lead might contribute to developmental delays by affecting early communication between caretaker and baby.

Acoustics↗
PubMedDate not supplied

Cellular target of streptomycin in the internal ear.

The cellular target of streptomycin (STP) was investigated by analyzing the activity of glutamate decarboxylase (GAD) or choline acetyltransferase (ChAT) enzymes of synthesis of GABA and acetylcholine (Ach), respectively, [supposedly located in hair cells (GAD) or efferent terminals (ChAT)] in control and in 50 day-STP-treated colored guinea pig vestibular homogenates. Vestibular and auditory function were assessed by measuring postrotatory nystagmus response (PNR) and auditory brainstem evoked potentials (ABP). Morphological changes were followed by light and electron microscopy. STP-treated animals exhibited a GAD decrease of 83.6% with respect to controls whereas ChAT did not suffer any change. Assessment of PNR and ABP showed that STP affected only the former since animals lost it between the 20th and the 30th day of treatment, whereas ABP was not modified. Morphological experiments detected vestibular hair cell deterioration as the only cell type affected by STP. These results confirm the predilection of STP to affect vestibular function by damage to hair cells and show that this effect can be followed by measurement of GAD and ChAT in the vestibule as markers for hair cells and efferent terminals, respectively.

Animals↗
PubMedDate not supplied

[Neurosciences and philosophy].

The goal of this paper is to show the paralelism between the objectives of both, neurosciences and philosophy. First, a historical review of the common works on both fields of study is made; next, the implications of the brain-mind relationship and how the use of a cerebral function theory that help us to solve the problem are discussed. Finally, the social implications of cooperation between neurosciences and philosophy are analyzed.

Brain↗
PubMedDate not supplied

[Risk factors for hypoacusis and audiometric findings in preschool children who had been admitted to neonatal intensive care units].

Thirty preschool children who survived from a neonatal intensive care unit were studied with pure tone audiometry between 125 to 8000 Hertz. Examinations were performed in a cross-sectional study at 36 to 72 postnatal months of age. Hypoacusis was found in three patients. Risk factors most frequently found in hypoacusic children were hyperbilirubinemia, hypoxia neonatorum and ototoxic exposure. All hypoacusic children had a history of preterm birth, one suffered hypoxia neonatorum, and two hyperbilirubinemia. The patients' group had an average of 2.26 risk factors. These data suggest that perinatal auditory damage occurs in the presence of additional hearing damage risk factors leading to hypoacusis.

Age Factors↗
PubMedDate not supplied

[Brain stem auditory evoked responses in rats. Effects of the development, stimulation rate and electrode placement].

Brainstem auditory evoked responses (BAER) were studied in Long-Evans rats in relation to development, stimulation frequency and electrode placement. Recordings made on day 11 of life showed no BAER. From day 14 on, four BAER waves were observed and centripetal maturational changes in wave latency were evident. Wave I attained adult latency values at day 20-22, wave II at day 24-25, wave II at day 24-25, and wave IV at day 39 of life. BAER latencies elicited by 8,000-Hertz tone-pips were shorter than those obtained with clicks and 4,000 Hz. Only wave II latency measures were affected significantly by electrode location.

Animals↗
PubMedDate not supplied

[Auditory evoked potentials in addicts to organic solvent inhalation].

Organic solvents affect the membrane lipids of neurons and glial cell. This led us to search for auditory damage, by means of brainstem auditory evoked responses, in subjects with chronic inhalation of thinner. Waves III and V showed delayed latency at an intensity of 90 dB, and wave V was delayed at 70 and 30 dB; the interwave intervals I-III and I-V at 90 dB and the interpeak I-V at 70 dB were also retarded. Three subjects did not show a response to stimulation at 30 dB: pure tone audiometry showed biaural mild hypoacusia in them. These results show that chronic inhalation of thinner may alter the auditory pathway of addicts.

Administration, Inhalation↗