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Biomedical subjects

E Soto

Publications and source records attributed to E Soto.

At least 55 records · Page 3Linked to original sources
PubMed1989

Computer simulation for teaching membrane potential fundamentals.

A computer simulation of membrane potential generation is presented. It allows the user to vary the intra and extracellular concentrations of sodium, potassium and chloride ions (Na+, K+ and Cl-), and determine the membrane potential and the equilibrium potential for each ion. The permeability coefficients for the ionic species considered, and the temperature may also be changed at will. Concentration-potential curves may be obtained at any time. The user may also select a voltage clamp option, which allows him to impose a certain membrane potential value, and study the resulting driving force for each ion. The use of the program in general physiology courses has shown it to be a useful aid for teaching the principles of membrane potential generation.

Chlorides↗
PubMed1989

Computer program for statistical Mann-Whitney U nonparametric analysis of neuronal spike activity.

A program for neuronal activity analysis is described. The applied computational techniques are standard in the field of digital processing, but the program is particular in its field of application and mode of data selection. The program, written in Turbo Pascal for the IBM-PC and compatibles, statistically compares (Mann-Whitney U-test) two sets of graphically selected data, and establishes whether there are significant differences between them. Although the program was developed for spike frequency analysis, it can easily be adapted to perform statistical analysis of other kinds of data.

Action Potentials↗
PubMed1988

Actions of excitatory amino acid acid agonists and antagonists on the primary afferents of the vestibular system of the axolotl (Ambystoma mexicanum).

In order to determine the nature of the transmitter in the synapse between hair cells and primary afferent fibers, both resting and evoked spike activity of vestibular system afferents were recorded. Excitatory amino acid agonists and antagonists were applied by micro perfusion. Excitatory amino acid agonists consistently increased the firing rate of these afferents. The rank order in potencies of the agonists tested was: kainate greater than or equal to quisqualate greater than D-aspartate greater than or equal to L-glutamate greater than or equal to L-aspartate greater than N-methyl D-aspartate. Blockade of synaptic transmission with high-Mg2+ and low-Ca2+ solutions did not seem to affect the responses to the excitatory amino acid agonists indicating their postsynaptic action. Excitatory amino acid antagonists inhibit both resting and physiologically evoked activity. The rank order of inhibitory potency was: kynurenate greater than L-glutamate diethyl ester greater than D,L-2-amino-4-phosphono-butyrate greater than D-alpha-amino adipate greater than D,L-2-amino-5-phosphonovalerate. These findings suggest that an amino acid-related compound may be the transmitter at this synapse. The relative potencies of agonists and antagonists tested provide evidence that the transmitter released from the hair cells' basal pole in the axolotl vestibular system interacts with postsynaptic kainic/quisqualic type receptors.

Action Potentials↗
PubMed1987

A Turbo Pascal program for on line spike data acquisition and analysis using a standard serial port.

A Turbo Pascal program for data acquisition and analysis is presented. The program detects incoming data as TTL pulses through the serial port of an IBM-PC and compatible computers and displays the instantaneous frequency plot and the interval histogram on-line. Novel features of this Pascal program are: no special hardware requirements and on-line analysis of more than one source at a time. No hardware additions to the supplied computer and easy operation make this program a valuable tool, directly useable in an IBM-PC and compatible computers.

Action Potentials↗
PubMed1987

Is GABA an afferent transmitter in the vestibular system?

This study was undertaken to determine the possible role of GABA as an afferent transmitter in the vestibular system of the axolotl. We studied the effects of GABA, muscimol, bicuculline and picrotoxin on the spontaneous spike discharge of the afferent fibers of the sacculi lagena and anterior semicircular canal. It was found that GABA and muscimol produce a very weak excitatory effect which does not mimic either the temporal course or the amplitude of the response of vestibular afferents to physiological stimuli. The GABA antagonist bicuculline has no significant effect on these fibers, and picrotoxin partially blocks the spontaneous activity in 33% of the fibers studied. These results indicate that GABA is probably not an afferent transmitter in the vestibular system as has previously been proposed.

Afferent Pathways↗
PubMed1986

A spike generator mechanism model simulates utricular afferents response to sinusoidal vibrations.

Using a model of spike generator mechanism (SGM) with a variable threshold we simulate the responses of utricular afferents to sinusoidal vibrations. It reproduces the phase locking characteristics (bifurcations diagrams) and the stimulus frequency firing rate relationships of different types of utricular afferents. We estimate the model parameters selecting the values which best fit the experimental results and we compare them with those from basic mechanisms involved in utricular codification.

Afferent Pathways↗
PubMed1986

Base-line data in a carcinogen-susceptible first-generation hybrid strain of Syrian golden hamsters: F1D Alexander.

Base-line data in over 600 control animals of both sexes of the first-generation hybrid BIO F1D Alexander strain of Syrian golden hamsters are presented. They involve mortality, body weights, spontaneous tumor incidence, and incidence of nonneoplastic lesions. The results confirmed previously published data on smaller numbers of animals of this hamster strain. Spontaneous tumors with an incidence of more than 2% were limited to lymphomas (less than or equal to 6%), adrenocortical carcinomas (less than 8%), adrenal adenomas (9-14% in males; 3.5% in females), islet cell adenomas (less than 6%), and follicular adenomas of the thyroid gland (3.5% in females only). This low incidence of spontaneous tumors and the high survival rate (compared to those of hamsters from other sources), together with the previously established high susceptibility to tumor induction by carcinogen administration, render the F1D Alexander hamster an excellent animal model for lifetime carcinogenesis bioassays.

Amyloidosis↗
PubMed1984

Is the Na+,K+-ATPase symmetrically distributed in the neuroepithelium of the vestibular system in the axolotl (Ambyostoma mexicanum)?

This study was undertaken to assess the localization of the Na+,K+-ATPase in the neuroepithelial cells of the macula sacculi. In vitro perilymphatic (basolateral) perfusion with ouabain produced a significant drop in the membrane potential. Endolymphatic (apical) application of ouabain had practically no effect on membrane potentials. This suggests that Na+,K+-ATPase is asymmetrically distributed in the neuroepithelial cells.

Acoustic Maculae↗
PubMed1984

Stimulation of progesterone synthesis in luteinized human granulosa cells by human chorionic gonadotropin and 8-bromo-adenosine 3',5'-monophosphate: the effect of low density lipoprotein.

Primary cultures of luteinized human granulosa cells reduced progestin secretion when taken from serum- and gonadotropin-containing medium into serum- and hormone-free medium. When added individually hCG, 8-bromo-cAMP and low density lipoprotein (LDL) stimulated progestin secretion by the cells after they spent 48 h in serum- and hormone-free medium. However, combinations of hCG or 8-bromo-cAMP and LDL were most effective in increasing steroidogenesis. The effects of hCG in enhancing steroidogenesis in the presence of LDL were first detectable after 3 h, but were most marked after 20 h of culture. hCG and 8-bromo-cAMP increased the conversion of [3H]cholesteryl linoleate, which had been incorporated into the core of LDL, into [3H]progesterone. hCG also stimulated cellular accumulation of LDL cholesterol, as assessed by incorporation of [1-14C]oleic acid into sterol esters or by measurement of total cellular cholesterol in the presence of amino-glutethimide to block steroidogenesis. In contrast to progesterone secretion, estradiol secretion was not affected by the addition of LDL in the absence or presence of 8-bromo-cAMP. We conclude that LDL cholesterol is required for maximal rates of progestin synthesis by human luteinized granulosa cells. When granulosa cells are stimulated by hCG, uptake of LDL cholesterol is promoted, and there is increased utilization of LDL cholesterol for steroid synthesis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1984

Changes during the menstrual cycle in cytosolic and nuclear concentrations of progestagen receptor in the human Fallopian tube.

[3H]R5020 was bound to cytosolic and nuclear samples of human Fallopian tube with high affinity and specificity. The cytoplasmic and nuclear concentrations of progestagen receptor varied, throughout the menstrual cycle, in the ampulla, isthmus and fimbria. Concentrations were higher at the late proliferative stage of the cycle than at the early proliferative and late secretory stages. A positive linear regression was observed between cytosolic and nuclear progestagen receptor concentrations and plasma oestradiol levels. A negative linear relationship was observed between cytosolic progestagen receptor concentration and plasma progesterone levels during the secretory stages of the menstrual cycle.

Cell Nucleus↗
PubMed1984

Preliminary study of hormone determinations during aminoglutethimide therapy for advanced breast cancer.

The aim of this study is to report on Aminoglutethimide-induced hormonal modifications in advanced breast cancer. Estradiol (E2), Testosterone (T), Dehydroepiandrosterone sulphate (DHEA(s] and Aldosterone (A) were determined before, and once every two weeks during treatment with Aminoglutethimide plus Hydrocortisone in 13 menopausal women with advanced breast cancer. The patients were selected either for their E2 and P4-receptor-positive in the original tumor or in metastases or by presenting objective clinical improvement to prior endocrine treatment. On the basis of the response to treatment the patients may be classified in two groups: 1) responders (n = 7) and 2) non-responders. No significant modifications of T concentrations were obtained in group 1 until after the first 8 months of treatment. One spontaneous menopausal patient with a T basal value of 0.80 ng/ml was evaluated during 12 months of treatment. From month 8, T diminished to values below 0.30 ng/ml, indicating a direct action of Aminoglutethimide, hydrocortisone or both drugs on ovarian steroidogenesis. The results obtained from the remaining hormonal parameters, evaluated in all the cases beginning from the second week of treatment, remained unchanged throughout the entire period of study. They were as follows: 1) E2 diminished with respect to basal values between 36 and 60%, thus confirming Aminoglutethimide inhibitory effect upon peripheral aromatization; 2) DHEA(s) diminished between 80 and 90%, indicating an adrenal inhibition due to the combined effect of both drugs, and 3) Aldosterone diminished to values between 80 and 110 pg/ml, these values being within the normal lower range.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Estradiol and progesterone nuclear and cytosol receptors of hydrosalpinx.

Hydrosalpinx is usually associated with a low intrauterine pregnancy rate following restoration of tubal patency by microsurgery. The biochemical evaluation of pathologic tubes from 11 infertile patients showed the presence of estradiol (E2) and progesterone (P) receptors at the cytosol and nuclear levels. The binding constants (Kd) for these specific proteins for E2 and Promegestone (R5020) were of the same magnitude as observed in normal tissue. Mean levels of E2 cytosolic and nuclear receptors and cytosolic P receptors of hydrosalpinx were significantly lower than those of a normal fallopian tube (P less than 0.05). No correlation between the severity of the histologic appearance of the tissue and the subcellular distribution of receptors was observed. We conclude that the decrease in the steroid receptor population of these damaged tubes could be counted as another factor to be considered in the poor intrauterine rate of the salpingoneostomy.

Adult↗
PubMed1983

Subchronic cigarette smoke inhalation studies in inbred syrian golden hamsters that develop laryngeal carcinoma upon chronic exposure.

Inbred BIO 15.16 Syrian golden hamsters were exposed for 6-20 weeks to smoke from three types of experimental cigarettes. The incidence and severity of laryngeal hyperplasia increased in these hamsters, a few (2) laryngeal papillomas appeared, alveolar macrophages became more frequent and aggregated, and hyperplasia of terminal bronchiolar epithelium occurred. This subchronic response of hamsters to smoke markedly differed for the three types of cigarettes. Statistical evaluation of the data by log linear models proved these differences to be significant. At equal doses of smoke, the most severe response was caused by an all-tobacco cigarette. The weakest subchronic effects, next to those seen in the negative control group, were elicited by smoke from a cellulose-derived tobacco supplement. The effects of smoke from a 1:1 blend of the two smoking materials were intermediate. The severity of the subchronic response of the respiratory tract paralleled the extent of malignant transformations of the larynx previously observed in the same animal model with the same three types of cigarettes in chronic inhalation studies.

Animals↗
PubMed1982

Changes in cytosolic and nuclear estradiol receptors of normal Fallopian tube throughout the menstrual cycle.

During the normal menstrual cycle, the changes in estradiol binding to cytosol and nuclear receptors of ampulla, isthmus and fimbria were analyzed. Cytosol estradiol receptor concentration showed little variation throughout the cycle, but were higher at the periovulatory phases. The concentration of nuclear estradiol receptor markedly varied in isthmus and ampulla; being significantly higher at the late proliferative phase than at the secretory phases. A positive linear correlation between nuclear receptor content and plasma estradiol concentration was observed, while a negative one was found with plasma progesterone.

Adult↗
PubMed1981

Estradiol dehydrogenase activity in the Fallopian tube during the normal menstrual cycle.

Simultaneous determinations of 17 beta-estradiol dehydrogenase activity (17 beta-HSDH) and of estradiol (E2), estrone (E1), and progesterone (P) were made in homogenates of human tubal tissue. The oviducts were obtained from 16 multi-parous normal women who requested sterilization; surgery was performed at different phases of the menstrual cycle. A significant decrease of E2 concentration with a concomitant increase of E1 was observed in the secretory phase of the cycle. The activity of 17 beta-HSDH was highest in the early secretory phase of the cycle with a significant difference (p less than 0.05) from the proliferative phase values. The results support the concept, that the activity of 17 beta-HSDH in the oviduct is regulated by progesterone.

17-Hydroxysteroid Dehydrogenases↗
PubMed1980

Unconjugated steroids in the fallopian tube and peripheral blood during the normal menstrual cycle.

Daily plasma samples were obtained from 22 high-parity normal women beginning on day 9 of the menstrual cycle. At varying times in the cycle, salpingectomy was performed and the excised tube was divided into isthmic, ampullary, and fimbrial segments. Simultaneous determinations of 17 beta-estradiol (E2), estrone (E1), and progesterone (P) in plasma and tubal tissue were carried out by specific radioimmunoassay. The highest ratio for E2 tissue to E2 plasma was seen at the time of the E2 peak. The E2 concentrations in the three anatomical segments of the fallopian tube during the late proliferative phase were significantly (P less than 0.05) higher than those during the early proliferative and late postovulatory periods. A significant (P less than 0.05) increase in P concentration was seen in both plasma and oviductal tissue after ovulation. The tubal tissue to plasma ratio had a tendency to decrease during the secretory phase, indicating a limited uptake of P during the secretory phase. The plasma levels of esterone were almost constant during the normal menstrual cycle. The highest concentration of E1 was seen in the fimbriae (254 +/- 71 pg/gm and ampulla (326 +/- 75 pg/gm during the early secretory phase of the cycle. The possible role of E1 during this crucial time of oviductal physiology is considered.

Adult↗