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Biomedical subjects

J L Clement

Publications and source records attributed to J L Clement.

At least 19 recordsLinked to original sources
PubMed2000

Identification of odorant receptors from the Alpine marmot (Marmota marmota).

Alpine Marmots (Marmota marmota) are a good model to study intraspecific chemical communication among mammals. This species has been subjected to several behavioural and biochemical studies regarding both their scent-marking behaviour by cheek-rubbing, and the chemical composition of their glandular secretions. However, no molecular study has been undertaken until today on proteins from the olfactory epithelium possibly implicated in chemical perception. In this study, we identified, to our knowledge for the first time, some olfatory receptors from this wild rodent. Starting with olfactory epithelium of an Alpine Marmot, and by mean of reverse transcriptase polymerase chain reaction technique (RT-PCR), we isolated fourteen partial sequences that exhibited a high degree of homology (45-92%) with olfactory receptors from other vertebrates. Conserved identities and structural features clearly defined these Alpine Marmot sequences as members of the seven transmembrane domain olfactory receptors. All sequences were observed as belonging to known olfactory receptor families and were classified into ten subfamilies of the tetrapods OR class. Finally, Northern blot analysis revealed specific expression of these sequences in the Alpine Marmot olfactory epithelium tissue.

Amino Acid Sequence↗
PubMed1995

Percutaneous extraction of vertebral osteoid osteoma under computed tomography guidance.

The authors report two osteoid osteomas of the spine treated by percutaneous extraction under computed tomography (CT) guidance. CT helps to localize exactly and extract only the nidus with no further damage to the bone. This technique is very promising, with a limited approach and minimal bone resection allowing a short hospital stay and prompt functional recovery.

Adolescent↗
PubMed1994

Percutaneous resection of osteoid osteoma under CT guidance in eight children.

In eight children with suspected osteoid osteoma, a percutaneous resection under CT guidance was performed. The specific drill resection system we currently use includes a 7-mm-diameter toothed drill. Osteoid osteomas were located in the appendicular skeleton in seven children and in the spine (second lumbar vertebral body) in one. All eight patients were successfully treated with complete relief of pain. There was no recurrence of symptoms during a follow-up period of 8-35 months. CT guidance was accurate enough to allow a focal bone excision, and no subsequent bone repair was needed. Histological confirmation was obtained in all cases. This simple and safe technique, when feasible, seems to be an effective means of treatment of osteoid osteoma in children.

Adolescent↗
PubMed1993

Osteoid osteoma: percutaneous resection with CT guidance.

In 24 patients with presumed osteoid osteoma in the appendicular skeleton (n = 23) and lumbar spine (n = 1), percutaneous resection with a drill system and computed tomographic (CT) guidance was performed. In the procedure, a 7-mm-diameter toothed drill inserted over a guide wire is used to remove the nidus. Twenty-three patients were successfully treated. Histologic confirmation of osteoid osteoma was obtained in 19 cases. In one patient, open surgery with bone grafting and osteosynthesis was necessary because of inadvertent extensive bone resection resulting from damage to the drill. All patients have remained free of pain and recurrence for 3-24 months. Although the procedure was effective in all patients, the 7-mm diameter of the toothed drill may cause difficulty in small bones or even danger in areas such as the posterior vertebral arch. In locations such as the tubular bones of the lower extremity and the femoral neck, however, this technique is feasible and may become the treatment of choice for osteoid osteoma.

Adolescent↗
PubMed1992

Cuticular hydrocarbons of Calliphora vomitoria (Diptera): relation to age and sex.

Changes in epicuticular hydrocarbon content and composition were examined from 3 to 120 hr postemergence in both sexes of Calliphora vomitoria. n-Alkanes and mono- and dimethylalkanes with 20 to 31 carbon atoms were the major hydrocarbons detected. Alkenes were only detected in the females. Males had fewer hydrocarbons (40 versus 49 for the females). In males this number remained constant from 3 to 120 hr, whereas in females the number increased progressively from 3 to 48 hr. The males had a greater total of hydrocarbons than the females (x6 versus x3.5). They had significantly more hydrocarbons by 48 hr, the time of sexual maturation, while in females, the hydrocarbon content increased between 6 and 24 hr postemergence, just before the onset of previtellogenesis. Hydrocarbon synthesis continued up to 120 hr in males, but remained constant in the females after 24 hr. Hydrocarbon composition differed in males and females and between the young (3 and 6 hr) and the older animals (24 to 120 hr). The young animals were characterized by the presence of monomethylalkanes with chain lengths over 25C and the older animals by monomethylalkanes with chain lengths less than 25C. Alkenes were found only in females. The males were characterized by the presence of di- and monomethylalkanes with 23, 24, and 26 carbon atoms.

Aging↗
PubMed1990

Relationships among hormonal changes, cuticular hydrocarbons, and attractiveness during the first gonadotropic cycle of the female Calliphora vomitoria (Diptera).

Attractiveness in adult females of Calliphora vomitoria is correlated with ovarian development and there is a marked increase during the previtellogenic and vitellogenic periods. The development of attractiveness may result from the combined actions of ecdysteroids and juvenile hormone. A rise in total hydrocarbons parallels the first increase in levels of these hormones during the previtellogenic stage. Cuticular hydrocarbons subsequently fall, along with the disappearance of hemolymphatic ecdysteroids, and then rise again during the vitellogenic phase of JH production. Increasing and decreasing of some cuticular hydrocarbons, some hydrocarbons implicated in the attractiveness, are correlated with variation of the titer of these hormones, especially JH III.

Animals↗
PubMed1985

Ventilatory responses to acute metabolic acidemia in humans awake, sedated, and anesthetized with halothane.

The authors produced metabolic acidemia acutely in human subjects awake, sedated with halothane (0.1 MAC), and anesthetized with halothane (1.0 MAC) by infusing L-arginine hydrochloride, 5-6 mmol X kg-1, over 3 h. Ventilation was recorded at resting arterial hydrogen ion concentration [( H+]a) and at 2-4 isocapnic increments of [H+]a, in each case, while end-tidal oxygen tension (PETO2) was varied between greater than 300 mmHg and 45 mmHg. Total increments of [H+]a in awake, sedated, and anesthetized subjects were 13 +/- 4, 12 +/- 2, and 12 +/- 3 nmol X 1(-1) (means +/- SD). In the awake state, metabolic acidemia increased ventilation (VI) in proportion to [H+]a. The magnitude of response increased with reduced PETO2, such that the response to acidemia and hypoxemia combined was synergistic. The delta VI/delta [H+]a slopes at PETO2 values of greater than 300, 100-120, and 45 mmHg were 0.47 +/- 0.27, 0.85 +/- 0.24, and 3.01 +/- 1.30 1 X min-1 X nmol-1 X 1, respectively (means +/- SD). Halothane sedation reduced the responses to added [H+]a determined at PETO2 values of 100-120 and 45 mmHg, as well as the response to hypoxemia and to the interaction of acidemia and hypoxemia, each to less than half awake values. Halothane anesthesia further impaired the responses to [H+]a and virtually abolished the response to hypoxemia and to acidemia-hypoxemia interaction. A small residual response to added [H+]a during anesthesia could be accounted for by a slight concurrent increase of PaCO2, leaving no response attributable to metabolic [H+]a itself.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1984

Effect of cimetidine premedication on morphine-induced ventilatory depression.

The potential respiratory interaction between morphine and cimetidine was studied by determining resting ventilation, PETCO2 and ventilatory response to added carbon dioxide in eight healthy volunteers on three separate occasions following administration of : (1) cimetidine 600 mg p.o., (2) morphine 10 mg IM, (3) morphine 10 mg IM preceded by cimetidine 600 mg p.o. Individual entry into the study was randomized and separated by at least one week. All measurements were determined at time 0, 30, 60, 120, 180, 240, 360, 480, 600, 720 minutes and at the end of 24 hours. In addition, serum morphine levels were measured in six subjects during the first six hours following morphine administration. Cimetidine alone had negligible respiratory effects. Morphine alone reduced resting ventilation, elevated PETCO2 and reduced the ventilatory response to added CO2, while the morphine-cimetidine combination caused a more profound depression of the CO2 response and delay in its recovery. No significant difference between resting ventilation and PETCO2 was observed. We conclude that cimetidine premedication interacts with morphine to prolong the respiratory depression but the magnitude of this interaction is small and clinically insignificant in healthy subjects. Caution, however, should be exercised in susceptible patients.

Adult↗
PubMed1984

Site of selective action of halothane on the peripheral chemoreflex pathway in humans.

Halothane in humans depresses the ventilatory response to hypoxemia in a manner that suggests a selective action on one or more components of the peripheral chemoreflex arc. To test the hypothesis that this action is at the carotid bodies themselves, the authors studied the ventilatory response to subanesthetic concentrations of halothane (0.15-0.30% inspired) in six fit volunteers maintained in a steady state of isocapnic hypoxemia (PEO2 50 mmHg). Upon exposure to halothane, hypoxemia-driven ventilation decreased promptly and progressively (from 7.5 +/- 1.2 1 X min-1 X m-2 in the control state to 5.9 +/- 0.9 and 4.8 +/- 0.7 1 X min-1 X m-2 at 30 s and 60 s of inhalation respectively, means +/- SEM). The relationship of hypoxemia-driven ventilation to end-tidal halothane tensions at 30 and 60 s of halothane wash-in (PEHal 0.4 and 0.6 mmHg, respectively) approached the relationship observed in near steady states of halothane inhalation. The results are interpreted as indicating that the site of selective action is at a tissue that accumulates halothane very rapidly during the first minute of inhalation. To make possible such pharmacokinetics, that tissue would require a location having a brief circulatory transit time from the lungs, and an extremely high rate of perfusion in relation to its capacity for uptake of halothane. The only tissue of the peripheral chemoreflex pathway that can satisfy these requirements is that of the carotid bodies.

Adult↗
PubMed1983

Chemical regulation of ventilation during isoflurane sedation and anaesthesia in humans.

To assess the effects of isoflurane on chemical regulation of ventilation, we studied the ventilatory responses to (1) hyperoxic hypercarbia, (2) isocapnic hypoxaemia, and (3) a single half vital capacity breath of carbon dioxide 20 per cent in oxygen in 12 human subjects, awake and sedated or anaesthetized with isoflurane, 0.1 or 1.1 MAC. Sedation did not alter ventilation nor the ventilatory response to hypercarbia but reduced the responses to hypoxaemia and to the half vital capacity breath of CO2. Anaesthesia reduced ventilation and the response to hypercarbia and nearly abolished the responses to hypoxaemia and to the breath of CO2. The results indicate that isoflurane reduces ventilatory responses to several chemical drives and that it selectively impairs those responses mediated by peripheral chemoreceptors. In these respects, isoflurane is similar to halothane and enflurane.

Adult↗
PubMed1983

[Experimental study of a growing acetabulum shelf (vascularized graft)].

The author has operated on 50 immature rabbits to perform a vascularised transplantation of the growing iliac crest to replace the rim of the acetabulum. Vascularity was preserved through the vascular pedicle and there was no need for vascular anastomosis. The results were assessed radiologically and by histological studies. The subsequent growth of the transplanted epiphysis could be illustrated in 15 out of 16 cases. The growing shelf had the advantage of good adaptation to the shape of the femoral head and produced a satisfactory physiological result.

Acetabulum↗
PubMed1982

Variable effects of anaesthetics on the ventilatory response to hypoxaemia in man.

We compared the ventilatory response to isocapnic hypoxaemia with a standard response to hyperoxic hypercarbia in human subjects sedated with methoxyflurane, diethyl ether or nitrous oxide, or anaesthetized with methoxyflurane. Compared to the awake state, methoxyflurane 0.1 MAC sedation did not alter either response significantly; methoxyflurane 1.1 MAC anaesthesia depressed both, with a somewhat greater effect on the hypoxaemic response. Diethyl ether 0.1 MAC sedation reduced only the hypoxaemic response. Nitrous oxide 0.1 MAC reduced both hypoxaemic and carbon dioxide responses in parallel. The evidence suggests that all three agents - like thiopentone, halothane and enflurane - can impair the ventilatory response to isocapnic hypoxaemia in man, but that in relation to the carbon dioxide responses, the magnitude of this depressive effect varies. Halothane and enflurane are the most depressant, nitrous oxide and thiopentone the least, with methoxyflurane and diethyl ether appearing to be intermediate in effect.

Adult↗
PubMed1982

Respiratory effects of nitrous during enflurane anesthesia in humans.

The authors measured resting ventilation, the ventilatory response to added CO2, the VD/VT ratio, the rate of carbon dioxide output, and arterial PCO2 in four healthy volunteers, awake and anesthetized with, in order (I) enflurane 0.4 MAC with nitrous oxide 70 per cent, (II) enflurane 1.1 MAC with nitrous oxide 70 per cent, and (III) enflurane 1.1 MAC alone. Enflurane 1.1 MAC reduced ventilation and the response to added CO2 markedly, increased the VD/VT radio, reduced rate of CO2 output, and elevated values of PaCO2 from 41 +/- 1 to 65 +/- 3 mmHg (mean +/- SEM). Enflurane 1.1 MAC with nitrous oxide 70 per cent had similar effects. Enflurane 1.1 MAC with nitrous oxide 70 per cent had similar effects. Enflurane 0.4 MAC with nitrous oxide 70 per cent caused much smaller changes in each measured respiratory variable, increasing PaCO2 values to only 49 +/- 1 mmHg. The results indicate that enflurane 1.1 MAC alone is too potent a depressant of alveolar ventilation to permit spontaneous breathing, but that the "equi-anesthetic" enflurane 0.4 MAC with nitrous oxide 70 per cent may not be. The magnitude of the beneficial respiratory effects of substituting nitrous oxide for an equivalent amount of vapor is substantially greater with enflurane than with either halothane or isoflurane.

Adult↗
PubMed1982

Assessment of two noninvasive monitors of arterial oxygenation in anesthetized man.

The Hewlett-Packard 47201A ear oximeter and the Radiometer TCM1 transcutaneous oxygen monitor were evaluated for use as noninvasive monitors of arterial oxygenation during inhalational anesthesia in man. Thirty-four healthy adult volunteers were anesthetized to steady states with halothane, enflurane, or isoflurane, and were studied either before or during surgery. Oxygen levels were varied over ranges that included hypoxemia, by manipulating FIO2. Oximeter estimates of SaO2 values and transcutaneous estimates of PaO2 values were compared with conventional measurements of each. Oximeter readings responded rapidly to changes of inspired oxygen concentration and were acceptably accurate estimates of SaO2, except at lower SaO2 levels (less than 80%) during anesthesia without surgery. Transcutaneous oxygen tension readings responded relatively slowly to changes of FIO2 and were frequently inaccurate reflections of PaO2 values. We consider this oximeter suitable as a monitor of arterial oxygenation during anesthesia, but find the transcutaneous electrode unsatisfactory.

Adult↗