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Biomedical subjects

D Bertrand

Publications and source records attributed to D Bertrand.

At least 199 records · Page 11Linked to original sources
PubMed1979

Pigment transformation and electrical responses in retinula cells of drone, Apis mellifera male.

1. Receptor potentials in honeybee drone retinula cells were recorded with intracellular micro-electrodes in the dorsal part of the superfused retina. The light stimuli were sufficiently weak that the response amplitude was proportional to the intensity. 2. Responses to stimuli of different wave-lengths, although of different amplitude, all had the same time course. 3. The maximal sensitivity in all the cells recorded from was to a wave-length between 450 and 460 nm. 4. Microspectrophotometry showed the presence of a pigment with two stable states, interconvertible by light, absorbing maximally at 445 nm (rhodopsin) and 505 nm (metarhodopsin). 5. There was a good match between the absorption spectrum of rhodopsin and the spectral sensitivity of retinula cells. 6. Transformation of a large fraction of rhodopsin to metarhodopsin by light reduced the sensitivity of the retinula cell but did not alter the shape of the relative spectral sensitivity curve or the time course of the responses. 7. It is concluded that for weak lights the receptor potential is determined only by the number of rhodopsin molecules that absorb photons: neither the presence of metarhodopsin nor its phototransformation to rhodopsin produces a detectable effect.

Animals↗
PubMed1978

Actions of EGTA and high calcium on the cones in the turtle retina.

1. The effects of Ca2+ on the activity of retinal cones were investigated by recording intracellular responses from turtle retinae perfused with solutions containing different Ca2+ concentrations. 2. Lowering extracellular Ca2+ concentration with EGTA increased membrane conductance and evoked depolarization in darkness. 3. Responses to bright lights were increased by EGTA by an amount equal to the depolarization in darkness; responses to dim lights instead were usually reduced. In addition EGTA modified the time course of responses to flashes. These changes were especially evident during the later phases of the response. 4. A steady light applied during EGTA perfusion can restore the original membrane potential. The kinetics of responses in these conditions, however, differ profoundly from those prevailing Ca2+ concentrations evoked hyperpolarization of the cones and decreased the amplitude of their responses to bright lights. The time course of responses to flashes was not appreciably modified by high Ca2+. 6. A steady light which hyperpolarizes the cone membrane by the same amount as high Ca2+ has an equal effect on the amplitude of responses to bright flashes but has an entirely different action on response kinetics and on the amplitude of responses to dimmer flashes. 7. The effects of EGTA on resting potential, conductance and response amplitudecan be interpreted assuming that the drug opens channels which are normally closed by Ca2+ in darkness. Conversely, the changes caused by high Ca2+ suggest that raising the concentration of outside Ca2+ reduces the number of light-sensitive channels open in darkness. 8. The observation that Ca2+ and light have different effects on kinetics and sensitivities is difficult to reconcile with the hypothesis that Ca2+ is the substance liberated by light to cause photoresponses.

Animals↗
PubMed1977

[The Bain anesthetic system in facial surgery].

The BAIN circuit was studied in 11 patients undergoing maxillofacial surgery, with no respiratory deficit, and under spontaneous and assisted ventilation, with a rate of flow of gas of 80, 100, 120, 140 ml/kg/min. From the results it could be concluded that this circuit should be used with a flow of at least 140 ml/kg/min, in assisted ventilation, in order to avoid any retention of CO2. Capnographic follow-up enabled better regulation of the flow rate necessary.

Anesthesia↗
PubMed1977

Familial resemblance of body weight and weight/height in 374 homes with adopted children.

Body weight and weight/height were measured in 535 children adopted at the median age of 3 months, and in 250 natural children in French-Canadian origin living in 374 Montreal homes, to determine whether the shared environment contributed to the familial resemblance of weight in children aged one to 21. The mid-parent vs natural children's correlation ( r2 X 100) was 9.55% for body weight and 6.60% for W/H (p less than 0.01), whereas the mid-parent vs adopted children's correlation was 0.00% for both characteristics. The sib-sib correlation in 80 homes with greater than 1 natural child was 15.2% for weight and 13.48% for W/H (p less than 0.001), whereas in 138 homes with greater than 1 adopted child, the adoptee-adoptee correlations were, respectively, 0.00% and 0.07%. It is concluded that heredity explains most of the familial aggregation of patterns of weight and weight/height in children. This conclusion does not necessarily apply to obesity, since weight indices in children do not accurately reflect excess fat tissue, and half of the adoptees were adopted after the age of three months.

Adoption↗
PubMed1977

[Electric burns in the operating room. Apropos of 4 cases].

Four cases of patients suffering from peroperative skin burns at electrocardioscope electrode sites are reported. They were the result of incorrect function of the cutting diathermy, (error of internal or external connection). Use of the electrocardioscope with a "floating input" protects the patient against this type of electrical accident.

Adult↗
PubMed1977

[26 cases of tracheal stenosis after prolonged intubation or tracheotomy. Personal retrospective study].

A retrospective study over a period of 10 years, involving different hospital departments, revealed a total of 26 patients with post-intubation and/or post-prolonged tracheotomy stenosis which required surgical treatment. Predisposing factors included poor general condition, infection, iatrogenic factors related to intensive therapy (respiration, inadequate nursing) and the duration. Stenosis were situated from the sub-glottis to the carina. After surgical treatment, there were ten cases of restenosis, two multiple, and one inflammatory granuloma. Intubation may be life-saving, but must be performed by an individual competent in the procedure, under strictly aseptic conditions, and using non-traumatic disposable material. The patient should undergo thorough ENT examination at the time of extubation, repeated one month and six months later.

Adolescent↗
PubMed1976

Familial aggregation of blood pressure in 558 adopted children.

Blood pressure was measured in each member of 398 French-Canadian families with at least one adopted child of the same ethnic origin. Measurements were made at home by a nurse, usually with the subject seated. One comparison per family between parents and randomly chosen index children was made, using age- and sex-adjusted scores. The correlation in blood pressure scores between parents and natural children was highly significant (P less than 0.001), at 10.2% for systolic and 13.7% for diastolic in 140 homes with at least one natural child, but the correlation between parents and adopted children was nonsignificant, at 0.81% and 1.0%, in 398 homes with at least one adopted child. The correlation between pairs of natural children was significant (P less than 0.05), at 7.84% for systolic and 8.41% for diastolic, in 80 homes with more than one natural child but nonsignificant, at 0.49% and 1.69%, respectively, for pairs of adopted children in 138 families with more than one adopted child. It is concluded that heredity explains most of the familial resemblance of blood pressure in children.

Adolescent↗
PubMed1976

Role of intracellular calcium and sodium in light adaptation in the retina of the honey bee drone (Apis mellifera, L).

In the honey bee drone, the decrease in sensitivity to light of a retinula cell exposed to background illumination was found to be accurately reflected by the difference in amplitude between the initial transient depolarization and the lowest steady depolarization evoked by the background light. It is shown that both the decrease in sensitivity to light and the accompanying drop in potential from the transient to the plateau can be prevented by injecting EGTA intracellularly. A decrease in duration and amplitude of responses to short test flashes such as observed immediately after illumination was found to occur too when Ca or Na, but not K, Li, or Mg injected into dark-adapted retinula cells. Injection of EGTA into a retinula cell maintained a steady state of light adaptation, was found to cause an increase in amplitude and duration of the response to a short test flash, thus producing the effects of dark adaptation. It is suggested that, in the retina of the honey bee drone, an increase in intracellular calcium concentration plays a central role in light adaptation and that an increase in intracellular sodium concentration, resulting from the influx of sodium ions during the responses to light, could lead to this increase in intracellular free calcium.

Adaptation, Ocular↗