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Biomedical subjects

P Glasson

Publications and source records attributed to P Glasson.

At least 19 recordsLinked to original sources
PubMed2002

Microwave saturation of the Rydberg States of electrons on helium.

We present measurements of the resonant microwave excitation of Rydberg energy levels for surface-state electrons on superfluid helium. The temperature-dependent contribution to the linewidth gamma(T) agrees with theoretical predictions and is very small below 700 mK, in the ripplon scattering regime. Absorption saturation and power broadening were observed as the fraction of electrons in the first excited state was increased to 0.49, close to the thermal excitation limit of 0.5. The Rabi frequency Omega was determined as a function of microwave power. High values of the ratio Omega/gamma confirm this system as an excellent candidate for creating qubits.

Journal Article↗
PubMed2001

Observation of dynamical ordering in a confined Wigner crystal.

We present measurements of the conduction of nondegenerate free electrons along a low-dimensional channel at low temperatures, using surface-state electrons on liquid helium in novel microelectronic devices. Above 1 K, the electrons form an ideal classical Drude conductor. Below 1 K, Coulomb interactions produce electronic spatial order, leading to strong non-Ohmic effects and negative differential conductivity. Evidence is presented for self-organized current filaments in the channel, created by a nonequilibrium phase transition. Periodic conductance oscillations suggest an anisotropic spatial order with lines of electrons along the channel edges.

Journal Article↗
PubMed1984

Circulating immune complexes in regularly dialyzed patients with chronic renal failure.

The prevalence of circulating immune complexes (CIC) was investigated using the C1q binding assay (C1q BA) and the conglutinin binding assay (Kg BA) in 200 patients undergoing maintenance hemodialysis. Increased C1q binding was found in 45% (87 of 194) of the patients, and the modified Kg BA gave elevated values in 31% (20 of 65). The prevalence of CIC was similar in American and Swiss patients, and in patients undergoing hemodialysis, self-dialysis or peritoneal dialysis. In patients with 'nonimmunological' renal diseases, CIC were detected with similar frequency. No change in CIC was noted during hemodialysis in 6 additional patients tested. The abnormality was not related to age, sex, duration of dialysis, hepatitis B antigenemia, bacterial infections, or transfusions. Anti-DNA antibodies were absent in all subjects tested and the results of the C1q BA were not changed by DNase digestion of eight sera with high C1q binding. Rheumatoid factor activity (RF) was detected in approximately one-fifth of the patients, and there was a direct correlation between positive C1q binding and RF. There was no correlation between CIC and lymphocytotoxic antibodies. This study demonstrated a high prevalence of CIC in dialyzed uremic patients and established its relationship to other immunological abnormalities.

Antibodies, Antinuclear↗
PubMed1984

Treatment of peritonitis in continuous ambulatory peritoneal dialysis patients with co-trimoxazole.

Peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) represents the most frequent and difficult problem related to this new form of treatment of ESRD patients. Various treatments have been reported previously. The aim of this study was to investigate the efficiency of a standardized initial treatment in 45 episodes of peritonitis. This was designed to be rapidly efficient, devoided of side-effects and easy enough to be performed by the patients themselves. When peritonitis was clinically suspected, patients received intraperitoneal co-trimoxazole (80 mg trimethoprim, 400 mg sulfamethoxazole), in each of the four daily bags concomitantly with 1,000 U heparin during 2 weeks and half of this dose during 2 other weeks. Our results demonstrate that 88% of the isolates were sensitive to co-trimoxazole and 85% of the patients completed this treatment. All were cured and no relapses were observed. Only 18 days of hospitalisation were required in the 45 episodes of peritonitis. Another anti-infective agent was used in 3 cases of gram-negative peritonitis and 4 other initially resistant to co-trimoxazole. It is concluded that initial treatment of CAPD peritonitis with co-trimoxazole is justified by the high proportion of sensitive germs and that it represents a safe, efficient and inexpensive treatment.

Adult↗
PubMed1983

[Treatment of arterial hypertension by plasmapheresis].

Plasmapheresis may induce transient hypotension in some patients. It may also be beneficial to patients presenting Raynaud's phenomenon where its effect may be explained by an improvement in the microcirculation due to decreased blood viscosity. Intrarenal microcirculation may be altered in patients who have impaired renal function, high plasma renin activity values and hypertension. Two such patients have been treated by plasmapheresis after unsuccessful multiple drug treatment. Blood pressure decreased to normal values after 2 or 3 plasmaphereses and drug treatment could be reduced. Twelve months after this treatment the blood pressure was still normal. Renal function was improved in one patient and unchanged in the other. Plasma renin activity, which was high before plasmapheresis, decreased dramatically but was not within normal limits after 8 exchanges. These two observations are preliminary but they render certain hypotheses possible. The decrease in plasma renin activity and improvement in renal function may be due to improved microcirculation. When blood pressure is not controlled by multiple drug antihypertensive treatment, plasmapheresis may be considered as an alternative therapeutic procedure.

Adult↗
PubMed1983

Interaction of diuretics and non-steroidal anti-inflammatory drugs in man.

1. The influence of four diuretics on renal prostaglandins was investigated in a study designed in two parts (A and B): A, 24 normal subjects on a constant sodium intake received frusemide (80 mg daily), or hydrochlorothiazide (100 mg), or triamterene (200 mg) or spironolactone (300 mg); B, the same subjects were pretreated for 3 days with indomethacin (150 mg daily), which was continued during the 3 day administration of the respective diuretics and during a 2 day post-diuretic period. 2. In study A, only triamterene provoked a rise in urinary prostaglandins E2 and F2 alpha (+ 474 +/- SEM 92%, P less than 0.01, and + 192 +/- 7%, P less than 0.01). In study B, prostaglandins were significantly inhibited in all subjects. After indomethacin, the natriuretic effect of frusemide and spironolactone was reduced by 80 +/- 12% (P less than 0.01) and 54 +/- 11% (P less than 0.001), whereas the natriuresis induced by hydrochlorothiazide and triamterene was unchanged. No correlation was found between urinary PGE2 and F2 alpha and natriuresis. 3. When triamterene was associated with indomethacin, two subjects developed reversible acute renal failure. 4. Plasma renin activity and urinary aldosterone were stimulated by the four diuretics in study A, but their response was blunted in study B. Urinary antidiuretic hormone was not modified by diuretics but was suppressed by indomethacin. 5. Diflunisal, a structurally unrelated nonsteroidal anti-inflammatory drug, given to 12 of the subjects provoked similar interactions with frusemide, hydrochlorothiazide and spironolactone. 6. The results suggest that prostaglandins contribute to the natriuretic effects of frusemide and spironolactone, but not to those of hydrochlorothiazide and triamterene.

Adult↗
PubMed1983

[Periarteritis nodosa: clinical presentation limited to severe kidney failure accompanied by arterial hypertension].

Two cases of severe renal failure and hypertension of a few weeks duration are reported. There were no symptoms nor signs suggestive of extra-renal involvement and the laboratory tests, more specifically those for the detection of inflammatory parameters, were normal. Renal angiograms revealed intraparenchymal arterial microaneuvrysms which led to the diagnosis of vasculitis of the periarteritis nodosa type. Combined immunosuppressive and steroid treatment was successful in both cases regarding blood pressure control and improvement of renal function. The importance of renal angiography as a diagnostic tool in this type of clinical setting is underlined, as well as the necessity for prompt and prolonged immunosuppressive therapy.

Adult↗
PubMed1982

[Isolated renal involvement in periarteritis nodosa].

Periarteritis nodosa (PAN) is a disease involving the kidneys in 70% of cases but always affecting other organs. Initial presentation with acute renal failure (ARF) and high blood pressure (HBP) is unusual. In two patients presenting those two features without any clinical or biochemical signs of other organ involvements, diagnosis of PAN was based on the presence of microaneurysms on renal angiograms. Combined immunosuppressive and steroid treatment resulted in control of blood pressure of both patients and improvement of renal function in one. ARF associated with HBP without evidence of other organ involvements is consistent with the diagnosis of PAN. In this clinical setting, renal angiography should be performed to confirm the diagnosis and establish the appropriate therapy.

Acute Kidney Injury↗
PubMed1982

Reversible acute renal failure from combined triamterene and indomethacin: a study in healthy subjects.

As part of a study on the interaction between diuretics and renal prostaglandins, four healthy medical students receiving indomethacin for 8 days were also given triamterene for 3 days. Whereas renal function was initially normal in all four subjects, creatinine clearance decreased in two by 62% and 72% after concomitant administration of the two drugs, and was only restored to normal after 4 weeks. In control periods when triamterene or indomethacin was given alone renal function was preserved in all subjects. Urinary prostaglandin E2 was stimulated by triamterene and inhibited by indomethacin in all four subjects; both changes were more marked in the two sensitive subjects. Thus prostaglandin inhibition by indomethacin may unmask triamterene toxicity and contribute to the pathogenesis of the renal failure observed in sensitive subjects. As alternative therapy is readily available, avoidance of this potentially nephrotoxic association is recommended.

Acute Kidney Injury↗
PubMed1981

[Retention of metabolites of a beta-blocking drug, oxprenolol, in renal insufficiency].

The pharmacokinetics in blood of oxprenolol and its glucuro-conjugated metabolites has been investigated in healthy volunteers and hemodialyzed patients; in addition, the effect of the drug on the heart rate has been measured. Renal insufficiency does not modify the elimination kinetics of oxprenolol, but it does lead to massive retention of the glucuro-conjugated derivatives on multiple dosing. The present study failed to show hydrolysis of the conjugates with liberation of the active parent compound. In addition, from measurement of the exercise-stimulated heart rate it can be concluded that active metabolites of oxprenolol are absent. The duration and intensity of the effect of a single dose of the drug were comparable in the healthy volunteers and the patients with renal insufficiency.

Biotransformation↗
PubMed1981

[Chronic ambulatory peritoneal dialysis].

Continuous ambulatory peritoneal dialysis for end-stage renal failure was first described in 1976. The purpose of the present study was to establish the value of this method in a group of eight patients with various renal diseases who were controlled monthly for one year. Main benefit was correction of anemia, better control of calcium and phosphate, and excellent blood pressure control. Hyperlipoproteinemia was observed in all patients, as was an increase in plasma renin activity and aldosterone. Thyroid values were in the low normal range. A low incidence of peritonitis was observed and cases of peritonitis were treated on an ambulatory basis. The results suggest that more patients could be included in this new treatment for end-stage renal disease.

Adult↗
PubMed1980

Interrelation between renal prostaglandins and the hormones involved in volume homeostasis by the kidney.

In this minireview studies performed in man are mainly summarized and the data obtained interpreted with the help of knowledge gained in previous animal and in vitro experiments. From all those results the picture of a rather tight interplay between renal prostaglandins, renin-angiotensin, aldosterone, and antidiuretic hormone (ADH) emerges, whereby renal prostaglandins synthesis appears to be partially regulated by angiotensin II and ADH; renal prostaglandins antagonize the biological effects of these peptide hormones, and directly or indirectly affect in their turn the release of renin and ADH.

Angiotensins↗