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Biomedical subjects

M Charton

Publications and source records attributed to M Charton.

36 records · Page 2Linked to original sources
PubMed1986

Quantitative description of side chain effects on binding to protein.

Values of delta delta G previously reported for transition state binding of ATP and tyrosine by tyrosyl-tRNA synthetase as a function of side chain structure are quantitatively described by the intermolecular force (IMF) equation. Polarizability, ionic side chains, and steric effects seem to be the major factors in determining delta delta G. A contribution from hydrogen bonding cannot be excluded but is at best probably small. Binding is apparently due to dispersion forces and ion/dipole and ion-induced/dipole interactions.

Adenosine Triphosphate↗
PubMed1986

[Anterograde ureteroscopy in the extraction of lumbar ureteral calculi].

Antegrade ureteroscopy can be used to extract certain lumbar ureteric stones in which the only alternative treatment is surgery. The technique of caliceal puncture is that of percutaneous nephrostomy: the ureteroscope is introduced through the Amplatz tube. The ureteric stone is removed by a basket probe, two-pronged forceps or hydroelectric shattering, 16 patients have undergone antegrade ureteroscopy; a rigid ureteroscope was used in 9 cases (2 residual fragments including 1 which migrated) and a flexible ureteroscope was used in 7 cases (3 failures). The overall success rate for the technique of 68% should improve with better selection of the indications (stone with a maximum diameter of 12 mm without retraction of the adjacent ureter and without kinking of the excretory tract) and with greater experience of the operators.

Endoscopy↗
PubMed1985

[Removal of ureteral calculi by uteroscopy].

Ureteral stones can now be removed endoscopically, using a ureteroscope. This instrument, provided with a direct optic system and an operating tube, is introduced under general anaesthesia after the ureteral opening has been dilated and is pushed up until it reaches the stone which is then removed by means of a basket catheter or a forceps. Voluminous stones can be shattered in situ by ultrasounds or hydroelectric shock waves. Forty-three stones, representing 72% of all attempts, were removed by this method from 30 patients. There were 6 failures due to impassable vesico-ureteral opening, ureteral flexure and wedged in or ascended stone, and 4 complications including 2 cases where the basket catheter went under the mucosa and 1 case each of secondary urinoma and ureteral clotting. There was no perforation nor overt septic complication. Most stones were larger than 10 X 4.5 mm and were located in the pelvic or iliac part of the ureter. Infected stones can be removed endoscopically under antibiotic treatment and provided a draining catheter is left in place. Ureteroscopy notably reduces the need for ureteral lithotomy.

Endoscopy↗
PubMed1985

Colonic perforation during percutaneous nephrolithotomy.

Of 250 cases of percutaneous nephrolithotomy perforation of the left colon has been observed in 2 men with mobile kidneys. The clinical signs were rectal hemorrhage with shock in 1 case and passage of gas through the nephrostomy tract in the other case. The perforation was not suspected during the nephrolithotomy. Both patients were treated surgically. In view of the risk of colonic perforation during percutaneous nephrolithotomy, great care should be taken during puncture. This risk is increased in cases with an excessively lateral tract or when the anatomical relationships are modified in subjects with mobile kidneys. Surgical repair is required when the perforation is intraperitoneal or when there is a risk of complications. Simple surveillance is only justified when the perforation is extraperitoneal and when there is no risk of complications.

Adult↗
PubMed1985

Some methods of obtaining quantitative structure-activity relationships for quantities of environmental interest.

Methods are described for obtaining quantitative structure-activity relationships (QSAR) for the estimation of quantities of environmental interest. Toxicities of alkylamines and of alkyl alkanoates are well correlated by the alkyl bioactivity branching equation (ABB). Narcotic activities of 1,1-disubstituted ethylenes are correlated by the intermolecular forces bioactivity (IMF) equation. When the data set has a limited number of substituents in equivalent positions the group number (GN) equation, derivable from the IMF equation, can be used for correlation. It has been successfully applied to aqueous solubilities, 1-octanol-water partition coefficients, and bioaccumulation factors and ecological magnifications for organochlorine compounds. A combination of the omega method for combining data sets for different organisms with the GN equation has been used to correlate toxicities of organochlorine insecticides in two species of fish. Toxicities of carbamates have been correlated by a combination of the zeta method and the IMFB equation. The ABB and the GN equations are particularly useful in that they generally do not require parameter tables, and that the parameters they use are error-free. The methods presented here, as shown by the examples given, should make it possible to establish a collection of QSAR for toxicities, bioaccumulation factors, aqueous solubilities, partition coefficients, and other properties of sets of compounds of environmental interest.

Biological Transport↗
PubMed1985

[Technic, failures and complications in the extraction of ureteral calculi using a rigid ureteroscope].

The authors describe the technique for the removal of ureteral stones by ureteroscopy. They stress the need to use perfectly suitable instruments (ureteroscope, baskets and ultrasound or hydro-electric lithotrites), and the importance of extreme gentleness in the manipulations and great patience. The time taken to perform a simple ureterostomy should not be compared to the time necessary for a complex endoscopic extraction. The quality of the dilatation counts for three quarters of the success. Fluoroscopic monitoring facilitates the operation. Ureteral drainage is necessary in the case of a long or fairly traumatic operation, or if there is urinary infection. With these precautions, rigid ureteroscopy can be used for three quarters of ureteral stones. Only one serious complication was registered: the rupture of the pelvic ureter during the extraction of a voluminous lumbar stone.

Cystoscopy↗
PubMed1985

[Passage of cefotiam into prostatic tissue].

20, 30 and 90 minutes after a single intravenous injection of 2 g of cefotiam prostatic tissue and serum samples were taken from 12 patients who underwent transabdominal prostatectomy for prostatic adenoma. Cefotiam was assayed by HPLC. Mean serum and prostatic concentrations were respectively 157 +/- 39 mg/ml and 42 +/- 23 mg/g at 20 mn, 77 +/- 52 mg/ml and 54 +/- 2 mg/g at 30 mn, 36 +/- 21 mg/ml and 16 +/- 18 mg/g at 90 mn. Elimination half-life of cefotiam was 1 h 39 mn for serum and 1 h 10 mn for prostatic tissue. These findings confirm the satisfactory diffusion of cefotiam within prostatic tissue, although saturation occurs after 30 mn. Treatment of prostatitis by cefotiam can be expected to give excellent results.

Adenoma↗
PubMed1984

[Single-dose preventive treatment of urinary tract infections after endoscopic resection of the prostate].

The ability of mezlocillin to prevent urinary tract infection after trans-urethral prostatectomy was evaluated in a randomized trial involving 100 patients (49 treated and 51 controls) with bacteria-free urine prior to surgery. One single 2 g dose of the antibiotic was administered intravenously 1 hour before the operation. Mezlocillin was chosen on the results of a preliminary study of post-trans-urethral prostatectomy urinary tract infections in 150 patients and was given as a single dose to prevent the development of multiresistant strains. Both groups of patients were comparable with regard to age, percentage of malignant tumours, weight of resected tissue and duration of post-operative bladder catheterization. Following surgery, bacteriuria (greater than or equal to 10(5) organisms/ml) was present in 18.4% of treated patients and in 51% of controls (p less than 0.001), the difference being significant on the 2nd and 5th post-operative days (p less than 0.01 and p less than 0.05 respectively). Clinical signs of infection were less frequent, and the duration of post-operative stay in hospital was reduced by more than 1 day in the treated group.

Clinical Trials as Topic↗
PubMed1984

[Eosinophilic cystitis of allergic origin].

Eosinophilic cystitis, of which 35 cases have been published, is a recurrent cystitis remarkable for its chronicity and for the importance of haematuria; the urine is usually sterile and blood eosinophilia frequently present; at histology, infiltration of the vesical wall by eosinophils is pathognomonic. In view of the irregular results of cortico-steroid treatment, a search for causative factors is required. Parasitic infestation has been suspected but never actually proven, and an allergic origin probably is frequently missed. We report two cases of eosinophilic cystitis where allergy to penicillin and clometacin respectively could be demonstrated for the first time and in which the condition subsided after withdrawal of these drugs.

Analgesics↗
PubMed1984

[Efficacy and tolerability of Negram Forte in the treatment and prevention of urinary infections in urologic surgery].

The authors sought to assess the efficacy and tolerance of a new oral form of nalidixic acid in the treatment of infections encountered in urological surgery. The study was based upon 30 cases. The urine was considered to be infected when more than 10(5)/ml organisms were present. Amongst 27 patients undergoing surgery, in 26 cases the operation was an endo-cavitary procedure involving the upper or lower urinary tract. The 3 non-surgical cases consisted of one patient with cystitis and two with prostatitis. In 6 patients, treatment was preventive, the urine being sterile before urological surgery. In the other 24, infection was present at the time that treatment was begun. E. coli present in 20 patients was the predominant organism in the series. Tolerance of treatment was perfect in 27 cases. In the 6 cases of preventive treatment, prescription of the drug prevented a postoperative infection. In the 24 patients receiving curative treatment, there were 7 failures (29%) and 3 late recurrences (12.5%). Failures were all the more frequent when the dose was lower. The authors equally felt that the prescription of 4 grams per day in one case was unsuitable. Organisms isolated when treatment was seen to have failed were all resistant to nalidixic acid. In the context of urological surgery, where there is often a cause of reinfection (catheters), the prescription of a high dose of the drug is an essential factor in decreasing the risk factor inherent in treatment.

Adult↗
PubMed1983

[Percutaneous ablation of renal calculi].

Percutaneous removal of renal calculi under nephroscopy was attempted in 34 patients. There were 19 pyelic, 9 caliceal, 3 uretero-pyelic and 3 multifocal calculi. The attempt was successful in 30 cases, the stones being removed by immediate lumbotomy in the 4 cases where it failed; 2 caliceal calculi remaining in situ are being followed up. Complete removal was effected in 19 patients. The smaller calculi were directly removed with special forceps, and the larger ones were either fragmented with a lithotriptor or disintegrated by ultrasounds or intracavitary shock waves. The postoperative period was uneventful. Stay in hospital was reduced to 4 days on average and absence from work, to 8 days. Five patients experienced renal colics due to migration of small fragments. One case of haemorrhage was easily controlled. Percutaneous removal of renal calculi is an elegant, though delicate method which seems to be of interest in persistent or recurrent pyelic or caliceal stones, in small or medium size pyelic stones and in mobile and painful caliceal stones. It undoubtedly has its place in the treatment of renal lithiasis.

Endoscopy↗
PubMed1983

The dependence of the Chou-Fasman parameters on amino acid side chain structure.

The Chou-Fasman conformational parameters, P, for amino acid residues in proteins are shown to be a linear function of intermolecular force and steric parameters. For alpha- helix, coil and turn parameters, steric effects are predominant; whereas for beta-sheet parameters, intramolecular forces are predominant. Turn and coil parameters show little or no difference in their dependence which is different from that of alpha-helix and in some ways almost reciprocal. Factors which increase the probability of finding an amino acid residue in an alpha-helix usually decrease the probability of finding it in coil or turn. Values of P were calculated for several of the less common amino acids.

Amino Acids↗
PubMed1980

[Thrombo-embolism in urologic surgery. Prevention by heparin of antiprothrombic drugs. A retrospective report of 2,657 cases (author's transl)].

Three groups of patients undergoing urological operations were given a prophylactic regimen of either subcutaneous heparin (n = 1143), antiprothrombics (n = 944) or no medication (n = 570). Results were deemed through simple clinical criteria. They were similar for the whole of patients and for some types of surgery, pecularly protatic: Anticoagulation induced a significant lowering of the frequency of thromboembolism, heparin being more efficient than antiprothrombics. It does not increase the percentage of haemorrhages. More, peridural anesthesia is not contre-indicated by heparin. However, parietal problems appear to be more frequent among heparinized patients.

Adolescent↗