Biomedical subjects

H Hedelin

Publications and source records attributed to H Hedelin.

At least 55 records · Page 3Linked to original sources

PubMed1993

Effect of long-term oral testosterone undecanoate treatment on prostate volume and serum prostate-specific antigen concentration in eugonadal middle-aged men.

Testosterone undecanoate (160 mg/day) or placebo was given orally in a double-blind fashion for 8 months to 23 middle-aged men without urinary tract symptoms. Testosterone was found to increase the mean prostate volume by 12% (P < .012). The treatment suppressed the serum concentrations of sex-hormone-binding globulin and follicle stimulating hormone. The observed decrease in the mean serum concentration of luteinizing hormone was not statistically significant. The serum concentrations of prostate-specific antigen did not change as measured by two different well-validated immunometric assays. No changes in micturition habits or urine flow charts were reported.

Administration, Oral↗

PubMed1993

Citrate and urease-induced crystallization in synthetic and human urine.

The effects of citrate on the different phases of urease-induced crystallization were studied using Coulter counter techniques and optical microscopy. Citrate increased urine pH and markedly delayed the initiation of the crystallization (nucleation) in both human and synthetic urine. In synthetic urine, particle aggregation and especially particle growth were delayed and inhibited by citrate. In human urine, aggregation was distinctly inhibited by citrate. It appears that the susceptibility of urine to form crystals in the presence of urease activity is influenced by its citrate concentration.

Adult↗

PubMed1993

Analysis of stone fragility in vitro and in vivo with piezoelectric shock waves using the EDAP LT-01.

A total of 100 whole stones was fragmented in vitro at 3-minute intervals with piezoelectric shock waves using the EDAP LT-01 device until all fragments were less than 2 mm. Larger stones and stones with a high computerized tomography attenuation needed longer treatments for fragmentation. Smoothly bulging stones with an even structure according to plain x-ray films were also more resistant to the shock wave treatment. Calcium oxalate monohydrate stones were not more difficult to break than other types of calculi. Stone fragments from 100 patients after extracorporeal shock wave lithotripsy were also analyzed. The average size of the fragments collected was less than 1 mm. Larger stones produced larger fragments and required more treatment sessions.

Calcium Oxalate↗

PubMed1993

Serum concentration of prostate-specific antigen in relation to prostate volume in 50 healthy middle-aged men.

Fifty men without symptoms of prostatic disease, aged 40 to 66 years, were studied with respect to serum concentration of prostate-specific antigen (PSA) and volume of the prostate gland. PSA was determined with two immunometric assays, one using a radioactive label, the other a nonisotopic label. Prostate volume was determined by transrectal ultrasound examination using two different modes of evaluation and assessed by rectal examination. The simpler "ellipsoid method" underestimated the volume by 20% compared to planimetry of several sections but they were well correlated to each other. It was found that prostate volume increased by 0.4 ml per year of age increase. There was a curvilinear relationship between serum PSA concentration and prostate volume determined by ultrasound; no statistically significant relationship was found between PSA concentration and prostate volume by rectal examination. The results indicate that the diagnostic value of serum PSA, for prostatic malignancy, will increase if values are related to prostate volume determined by ultrasound examination.

Adult↗

PubMed1993

Crystal adherence to rat bladder epithelium after long-term E. coli infection.

The normal urothelium is covered by a mucous coat which acts as an unspecific barrier against the adhesion of bacteria, cancer cells and crystals. Acute bacterial infections cause disruptions of the mucous coat and impairment of its anti-adherent property. The effect of long-term infection is, however, not known. Live E. coli were inoculated into rat urinary bladders and a persisting infection was obtained by creating a small bladder diverticulum. After 2, 10 and 21 days a crystal adhesion assay showed a twofold increased adherence to the urinary bladder in the infected rats compared to control (p < 0.001). One possible explanation could be an injury to the mucous coat.

Animals↗

PubMed1993

Influence of Escherichia coli on urease-induced crystallisation in human urine.

Urease was added to urines inoculated with Escherichia coli 24 hours earlier and to control urines not inoculated with E. coli. The inoculation did not change the concentration of the measured urine components. The urease-induced ammonium ion production and pH increase was reduced in E. coli-inoculated urines compared to control urines. This suggests that E. coli can inhibit urease. The precipitation of both phosphate and magnesium on glass rods inserted in the urine was reduced with 40-50% in the E. coli-inoculated urines. The results demonstrate that E. coli can influence urease-induced crystallisation.

Adult↗

PubMed1992

The influence of pH and urine composition on urease enzymatic activity in human urine.

It is reasonable to assume that the rate of pH increase in urine induced by urease-producing microorganisms is one of the factors which determine whether crystallisation with subsequent stone formation will occur or not. To evaluate how the time needed to increase urine pH varies between different urine samples and how it depends on urine composition, a standardised amount of urease was added to different human urine samples. The incubations were performed in a pH-stat. This allowed simultaneous study of how urease enzymatic activity depends on urine pH and how it varies between different urines. The enzymatic activity was found to be negatively correlated to urine pH and to vary between different urines. The rate of the pH increase varied markedly between different urines. Small pH increases depended on the native urine pH and urease enzymatic activity. Higher pH increases up to the levels of phosphate crystallisation depended more on urine phosphate, the major urine buffer. The results presented show that urine composition influences the urease-induced pH increase. This might have clinical implications.

Adult↗

PubMed1991

Urease-induced precipitation of phosphate salts in vitro on indwelling catheters made of different materials.

The urease-induced precipitation of phosphate salts on indwelling catheters was studied in an experimental in vitro model. The precipitation was strongly pH-related and was much higher in synthetic urine than in human urine. In the latter, it was significantly lower on silicone catheters than on latex catheters, including those with a hydrophilic coating. The precipitation on silicone catheters that had been in situ was not increased as compared with that on unused catheters, in contrast to latex catheters with a hydrophilic coating, among which the precipitation on used catheters was higher.

Catheters, Indwelling↗

PubMed1991

Studies of urease-induced crystallisation in undiluted human urine using the Coulter counter technique.

Urease-induced crystallisation was studied in different human urine samples after urease incubation. The studies were performed using the Coulter counter technique, which enables determination of the number and size of particles in a solution and calculation of the total particle volume. The crystallization took place in three consecutive but overlapping steps: (1) nucleation, (2) growth and (3) aggregation. The maximal number of particles obtained in the different samples varied little, but there was a great variation in particle size and total particle volume. The variation in particle size appeared to be mainly due to differences in particle growth, a factor that might be of importance for stone formation.

Adult↗

PubMed1991

Influence of indomethacin on the adherence of urease-induced crystals to rat bladder epithelium.

The mucous coat lining the urinary tract has a barrier function which prevents bacteria and crystals from adhering to the uroepithelium. The mucous coat of the gastric mucosa is sensitive to prostaglandins, and prostaglandin synthetase inhibitors induce gastric erosions and disrupt the continuity of the mucous lining. To determine whether prostaglandin synthetase inhibitors also exert a similar effect on the uroepithelium, rats were given indomethacin intraperitoneally or orally. The effect of this treatment on the adhesion of urease-induced crystals to rat bladder mucosa was studied using a previously developed in-vivo method. Both when given intraperitoneally and orally in a dose of one mg. per kg. b.w. for six weeks, indomethacin significantly increased crystal adherence. This constitutes indirect evidence for the concept that prostaglandins influence the mucous coat of the rat urinary tract and reduce its antiadhesive properties.

Adhesiveness↗

PubMed1991

Relationship between urease-producing bacteria, urinary pH and encrustation on indwelling urinary catheters.

In 11 patients with long-term indwelling catheters the amount of catheter encrustation and urinary pH were measured and the urine regularly cultured over a prolonged period of time (median of 7 periods of 3 weeks). The mean urinary pH was related to the persistent presence of urease-producing micro-organisms (P. mirabilis) and urinary pH governed the precipitation of catheter encrustation. The critical pH appeared to be around 6.8. In patients with a mean urinary pH below this level the encrustation was minute (less than or equal to 2.9 mg phosphate). In patients with a mean urinary pH above 6.8 it was considerable but with a marked interindividual variation (35.5-138.7 mg phosphate). The composition of the encrustation was also strongly pH-related, with a much higher proportion present as magnesium ammonium phosphate in patients with a mean urinary pH above 6.8. The persistent presence of urease producers was not associated with a high pH or a more pronounced precipitation of phosphate in all patients. The amount of encrustation thus appears to depend not only on the presence of urease-producing micro-organisms but also on individual factors such as urinary composition.

Aged↗

PubMed1991

Outpatient-based extracorporeal shock wave lithotripsy using EDAP LT-01.

Between March 1988 and March 1990, 751 patients were treated with shock wave lithotripsy using EDAP LT-01. Six hundred and eight patients had renal stones while 143 patients had stones located in the ureter. Because of difficulties in locating ureteric stones with ultrasound 92% of them were pushed back to the kidney before treatment. The mean stone size was 10 mm, range 4-30 mm. Patients with stones bigger than 15 mm had a double J-stent placed before treatment. The mean number of treatments per patient was 1.7 (range 1-8). Sixty-six per cent of the patients with renal stones were completely stone-free after ESWL monotherapy. Another 5% became stone-free after auxiliary procedures in the ureter, because of retained fragments. Fragments equal to or less than 4 mm were retained in 14% of the patients with the renal stones. Of the patients with ureteric stones mobilised back to the kidney 95% were rendered stone-free after ESWL. Most patients experienced no or very little discomfort during the treatment and only 29% of them received analgesics. General of epidural anaesthesia was given to 1% of the patients. Because of the low demand for analgesia or anaesthesia, 99% of the patients with renal stones were treated on an outpatient basis. During the second year, 74% of the patients with ureteric stones were treated on an outpatient basis.

Adolescent↗

PubMed1990

The effects of fractioned human urine on urease-induced crystallisation in vitro.

Previous studies have shown human urine to have an inhibitory action on urease-induced crystallisation. Centrifugation and 0.45 microns filtration of the urine did not reduce this activity. This eliminates larger urine particles as being the cause of the inhibitory activity. Both the retenate and the filtrate after ultrafiltration of urine with a 100.000 mol weight cut-off influenced the urease-induced crystallisation of magnesium ammonium phosphate and calcium phosphate. The results indicate that the inhibitory action is exerted by more than one urinary component.

Calcium Phosphates↗

PubMed1990

Effects of serum, albumin and immunoglobulins on urease-induced crystallization in urine.

The effects of serum, albumin and gammaglobulins on urease-induced crystallization have been studied in synthetic and in human urine. Serum and the studied proteins increased urease enzymatic activity in synthetic urine. In human urine only serum had this effect. In synthetic urine, the proteins and serum markedly decreased the precipitation attached to glass surfaces, while the intraluminal precipitation was increased. In human urine, similar but weaker effects on the precipitation were found for serum and albumin. These findings suggest that the proteins studied, in the concentrations in which they are present in human urine, have profound effects on urease-induced crystallization and may be physiological crystallization inhibitors.

Crystallization↗

PubMed1990

How variations in the composition of urine influence urease-induced crystallization.

To Study how the composition of urine influences urease-induced crystallization, human urine samples were incubated with urease and the subsequent precipitation measured. Beside the pH increase, the urinary content of magnesium and calcium had profound effects on the precipitation of magnesium ammonium phosphate and calcium phosphate, respectively. Urine phosphate, ammonium and osmolarity had no direct effects on the precipitation. Among the urine components with potential inhibitory properties, only albumin was found to be correlated with such an effect. This inhibitory activity was especially influential in urines with high calcium and magnesium levels. These findings suggest that the composition of urine could also influence the formation of stones consisting of magnesium ammonium phosphate and calcium phosphate.

Calcium Oxalate↗

PubMed1990

Bacteriology of upper urinary tract stones.

Extensive cultures of stones and urine were performed in 215 patients who underwent an operation for upper urinary tract calculi. Microorganisms could be cultured from the stone in 1 of every 3 patients. Despite the extended culture technique urease-producing microorganisms could be cultured from the stone in only 48% of the patients with calculi that contained magnesium ammonium phosphate. This finding suggests that an infection with urease-producing microorganisms is not obligatory for the formation of this type of stone. Of the patients with calcium oxalate phosphate stones 32% had positive stone cultures, which distinguished them from patients with pure calcium oxalate stones, only 8% of whom had a positive stone culture (p less than 0.001).

Adolescent↗

PubMed1990

The bacteriology of operated renal stones.

In a group of patients consecutively operated on for renal stones, more than half of the patients had urinary tract infection. In a significant number of the patients with infection stones containing magnesium ammonium phosphate, no urease-producing microorganism could be cultured. Escherichia coli was on the other hand rather frequently cultured from the stone in these patients. This suggests the possibility that E. coli might be involved in stone formation. The correlation between stone and voided urine cultures was incomplete. It is thus important to perform stone cultures. This could be done without loss of accuracy by culturing crushed stones.

Adolescent↗

PubMed1990

E. coli and urease-induced crystallisation in urine.

The effects of urine preinoculation with E. coli for 20 h on urease activities in urine have been studied in synthetic as well as human urine. The E. coli preinoculation increased pH in both synthetic and human urine. Urease enzymatic activity was enhanced in E. coli-preinoculated synthetic urine. The intraluminal urease-induced precipitation was increased in E. coli-preinoculated synthetic urine. The precipitation on glass rods, which more closely reflects crystal growth and aggregation, was reduced. The process of urease-induced crystallisation thus appears to be influenced by E. coli. In human urine, the effects of E. coli preinoculation were less uniform but a significantly increased urease-induced precipitation after E. coli preinoculation could be reproduced in human urine also.

Adult↗