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Biomedical subjects

C Lambert

Publications and source records attributed to C Lambert.

At least 91 records · Page 5Linked to original sources
PubMed1985

Influence of heart failure and sodium content in the diet on the natriuretic response to furosemide in hamsters.

The aims of this study were to investigate the influence of heart failure and dietary sodium content on the natriuretic effect of furosemide. Ten healthy Golden Syrian hamsters (HH) and 10 hamsters with a cardiomyopathy (CMH) were maintained on a normal sodium diet (NSD) and an equal number of animals on sodium deficient diet (SDD) for a minimum of 40 days. Three experiments were conducted on days 1, 20 and 40. Each experiment started with a 24-hour urine collection (control), followed by the administration of 5 mg/kg of furosemide i.p. and a second 24-hour urine collection and finally, the administration of 2 mg/kg of indomethacin i.p. followed 30 minutes later by 5 mg/kg of furosemide and a 24-hour urine collection as well as blood sampling. Sodium, creatinine, furosemide and arginine vasopressin (AVP) were measured in the urine and sodium, creatinine and AVP in plasma. After 134 days on a SDD, four HH resumed a NSD and the response to furosemide was again assessed after 12 days. Our results indicate that the natriuretic response to furosemide is higher in CMH than in HH. The SDD tended to increase the response to furosemide in HH as well as in CMH. Indomethacin did not influence the response to furosemide under any experimental condition. In four HH the increment in the fractional excretion of sodium in response to furosemide was 0.88 +/- 0.21% after 134 days on SDD and decreased to 0.35 +/- 0.12 (p less than 0.05) after 12 days on NSD. In all cases urinary excretion of furosemide was similar. Plasma AVP was higher in CMH and was not influenced by the SDD. In conclusion, SDD as well as cardiomyopathy with congestive heart failure do not decrease the natriuretic effect of furosemide and may not be a cause in the variability of the natriuretic response to furosemide.

Animals↗
PubMed1983

Effects of phenobarbital and tobacco smoking on furosemide kinetics and dynamics in normal subjects.

This study was carried out to determine whether furosemide (F) kinetics and dynamics were influenced by phenobarbital and tobacco smoking. Our subjects were 10 normal men: five nonsmokers (NS) and five smokers (S). They received a single intravenous F injection of 40 mg. Regular serum and urine collections were made. In a second study, the NS group received 100 mg phenobarbital orally for 15 days and then a second dose of F. Cumulative 8-hr urinary excretion of sodium was identical for NS, NS with phenobarbital, and S at 345 +/- 30, 357 +/- 29, and 353 +/- 25 mmol. Diuresis was smaller by 800 ml (20%) in S than in NS. F increased endogenous creatinine clearance from 117 +/- 13 to 196 +/- 17 ml/min in NS and from 110 +/- 12 to 222 +/- 30 ml/min in NS with phenobarbital. In the S group, endogenous creatinine clearance showed a tendency to increase only slightly, from 136 +/- 23 to 180 +/- 34 ml/min. The increase in free water clearance caused by F was smaller in the S group than in the NS group (P less than 0.05). Protein binding and distribution of F were not affected by phenobarbital or tobacco smoking. F clearance was slightly higher in S than in NS, which was primarily the result of a slight increase in extrarenal F clearance. In the NS group, F clearance remained constant after phenobarbital. It is concluded that tobacco smoking in normal subjects affects the diuretic response to F without modifying kinetics.

Adolescent↗
PubMed1983

Spontaneous electrodermal activity during sleep in man: an intranight study.

This study was designed to examine the intranight evolution of spontaneous electrodermal activity (EDA). Eight paid volunteer male students were recorded for 3 complete nights (after a habituation night). The results show that: during the first sleep cycle, EDA is significantly lower than during the rest of the night; rapid eye movement sleep evolves in a particular manner, which emphasizes the specificity of this sleep stage; and there is no internight habituation effect.

Adult↗
PubMed1982

Nonrenal clearance of furosemide as a cause of diuretic response variability in the rat.

In clinical practice, the patient-to-patient variability in furosemide response is a well known fact. To study whether changes in furosemide metabolism may contribute to this variability, 72 rats received furosemide in a dose of 5 mg/kg i.p. There was a good correlation between the percentage of furosemide recovered in the urine and the diuretic effect. Accordingly, the rats were separated into groups corresponding to good responders (GR) and poor responders (PR) based on the extent of diuresis and the percentage of furosemide recovered in the urine. In an in vivo experiment, 12 rats received 30 mg/kg of chloramphenicol i.p. 30 min before furosemide. In PR rats, the average percentage of furosemide (+/- S.D.) in urine increased from 24.1 +/- 6.3 to 67.1 +/- 8.9 (P less than .001) and urine volume increased from 13.5 +/- 4.6 to 28.6 +/- 3.5 ml/24 hr (P less than .005). No such changes were observed in the group of GR rats. In a subsequent experiment, 11 GR rats received 80 mg/Kg of phenobarbital i.p. for 5 days before furosemide. The percentage of furosemide recovered in the urine decreased significantly (53.4 +/- 10.2 to 39.8 +/- 7.2, P less than .01), although the diuretic effect was not modified. In vitro studies confirmed that the T 1/2 of furosemide biotransformation in liver was different in GR and PR rats: 63.6 +/- 5.5 vs. 43.5 +2- 2.8 min, respectively (P less than .001). After receiving chloramphenicol, PR rats showed a longer T 1/2 of biotransformation in liver of 54.8 +/- 6.4 min (p less than .05 when compared to PR controls). After the administration of phenobarbital, GR rats showed a short T 1/2 of 35.3 +/- 7.0 min (P less than .005 when compared to GR controls). It is concluded that in the rat, the variability in diuretic responses to furosemide is related to the capacity of the individual rat to metabolize furosemide and that furosemide metabolism may be inhibited by chloramphenicol and increased by phenobarbital.

Animals↗
PubMed1981

Polyribosome analysis on sucrose gradients produced by the freeze-thaw method.

Polyribosomes were analyzed on sucrose gradients produced by the freeze-thaw method. When gradients were formed from a starting solution containing 1 mM Mg2+ an anomalous sedimentation pattern was observed although the polyribosomal structure can be maintained at this Mg2+ concentration. The use of starting solutions containing 5--20 mM Mg2+ yielded a satisfactory sedimentation profile of polyribosomes on freeze-thaw produced gradients.

Cell Fractionation↗
PubMed1981

Social skills and somatotype.

The hypothesis that somatotype is closely related to social skills and that the response of patients with social disability to social skills training might also relate to these genetically controlled factors has been supported. Twenty-one subjects seeking treatment for social phobia were assessed by interview, videotape, diary, and somatotype measures. Ectomorphs used less non-verbal communication and endomorphs were more restless. Women used fewer gestures but their speech was less hesitant than men. Social skills training benefited the shorter, plumper physique more than the linear ectomorph and, to some extent, and independently, the older subjects.

Adult↗
PubMed1981

Drug absorption: a practical method to estimate the absorption rate constant.

A simple equation is proposed to estimate the apparent absorption rate constant (Ka). In order to test this equation, experimental data were obtained following the oral administration of 10 mg/kg of sulfamethazine (SMZ) to ten normal volunteers. The Ka was estimated in three ways (by the proposed equation, by the method of residuals and by the method of the percent unabsorbed versus time plots), and then compared to the value obtained using a NONLIN computer program. The validity of the calculated Ka was further tested by performing computer simulations and estimating the quality of the fit by comparing the coefficient of regression. It was concluded that with the proposed relationship, the estimated values of Ka are closer to the results obtained with the NONLIN method than are the Ka values calculated with graphical methods. Moreover, the calculated method has the advantage that the accuracy of the estimated Ka is not affected by fast absorption, as long as a plasma concentration prior to the peak is known and that the relationship is easy and practical to handle. The one limitation to the proposed method is that it can only be applied to drugs distributed into a single compartment.

Adult↗
PubMed1980

The effect of protein concentration on the activity of beta-fructosidase from radish seedlings.

Radish beta-fructosidase (beta-D-fructofuranoside fructohydrolase, EC 3.2.1.26) is inactived by diluting the enzyme solution and the activity can be restored by addition of bovine serum albumin or other proteins. The use of detergent, high molar salt solutions or silicone-coated tubes showed that decrease of specific activity upon dilution is not linked to adsorption of the enzyme on to glass walls. Albumin neither protects the enzyme from denaturation by heat nor changes its stability during conservation at room temperature. The action of added proteins is not due to removal of an inhibitor from the enzyme solutions. Some polyanions or polycations have the same effect as albumin, but dialysis or chromatography show that they do not act by reassociation of inactive products formed by dilution of the active enzyme. A molecular weight heterogeneity is observed in the enzyme population when chromatography is performed without albumin. This suggests that inactive forms, formed upon dilution, differ slightly in their molecular conformation from the active forms obtained at high protein concentration.

Adsorption↗
PubMed1980

Psychological complications from the use of hypno-sedatives in dental practice.

The use of hypno-sedatives in dentistry, diazepam, and nitrous oxide, may result in psychological sequelae for the patient. These problems are not remedied by technical approaches to treatment. They may be decreased by a better understanding of suggestion, personality, and anxiety. The study of the use of suggestion is recommended.

Abreaction↗