Search PubMed⌕ Search

Biomedical subjects

H G Tiselius

Publications and source records attributed to H G Tiselius.

At least 19 recordsLinked to original sources
PubMed1997

Estimated levels of supersaturation with calcium phosphate and calcium oxalate in the distal tubule.

Approximate estimates of the ion-acitivity products of calcium phosphate and calcium oxalate in distal tubular urine were derived from the 16-h urinary excretion of calcium, oxalate, citrate, magnesium and phosphate. Urine variables were obtained from 96 normal subjects and 277 calcium stone formers and the calculations were carried out with iterative approximation using the EQUIL2 program. With respect to other ions of importance for the ion-activity products, the urine was assumed to have a fixed composition with pH 6.45. Significantly higher ion-activity products of both calcium phosphate and calcium oxalate were recorded in stone formers. It was concluded that diurnal variations in urine composition and pH might result in peaks of calcium phosphate supersaturation in distal tubular urine whereby a crystallization can occur. In association with abnormalities in terms of promotion and inhibition of calcium salt crystallization, such a precipitation can be of importance for the subsequent formation of calcium renal stones.

Calcium Oxalate↗
PubMed1997

Autoantibodies and primary Sjögren's syndrome in a hypocitraturic stone population.

Primary Sjögren's syndrome may be complicated by distal renal tubular acidosis (dRTA) and hypocitraturia, which are risk factors for calcium stone formation. Approached from a different perspective, in patients with urolithiasis and dRTA, autoantibodies and various autoimmune diseases are not uncommon. In search for signs of autoimmune disease, we analysed antinuclear antibodies and total levels of serum IgG in 197 hypocitraturic stone formers (67 women and 130 men). Antinuclear antibodies were present in 1.5% of the men and in 18% of the women. An isolated increase in serum IgG was found in 9% of the men and in 3% of the women. Anti-SS-A antibodies were analysed in a subgroup of 46 women and were estimated to occur in 16% of all hypocitraturic stone forming women. Four of 4 examined women, but no men, fulfilled the criteria of definite or possible primary Sjögren's syndrome. We recommend the analysis of anti-SS-A antibodies in female hypocitraturic stone formers.

Adult↗
PubMed1996

Risk factors of calcium stone formation in patients with primary Sjögren's syndrome.

Distal renal tubular acidosis (dRTA), which occurs in patients with primary Sjögren's syndrome (SS), is a risk factor for the development of urolithiasis. Twenty-seven patients with SS were evaluated with respect to biochemical risk factors of calcium stone formation. Sixteen had no history of urolithiasis (group 1) whereas 11 had such a history (group 2). The stone composition was known for seven of the patients, and calcium phosphate was the major stone constituent in all of them. dRTA was present in all patients in group 2, and in 7 of the 16 patients in group 1. Hypocitraturia was common in both groups, and the urinary excretion of citrate did not differ between the two groups. There was a higher urinary excretion of calcium and urate in group 2 and this group also had a higher urine volume. The risk of forming a urine supersaturated with calcium oxalate (CaOx) expressed in terms of AP(CaOx)index(s), which is an approximate estimate of the ion-activity product of CaOx calculated for a 24-h urine volume of 1500 ml, was higher in stone formers. A similarly derived estimate of the ion-activity product of calcium phosphate, AP(CaP)index(s), was calculated for a urine pH of 7. Although AP(CaP)index(s) was not significantly higher in group 2, there was a good correlation between AP(CaP)index(s) and AP(CaOx)index(s). We conclude that the urine composition in patients with SS, dRTA and urolithiasis is similar to that of other stone-forming patients with dRTA, and recurrence preventive therapy can be designed as for these patients.

Acidosis↗
PubMed1996

Is citrate an inhibitor of calcium oxalate crystal growth in high concentrations of urine?

The effect of citrate on calcium oxalate (CaOx) crystal growth was studied in a system in which series of samples containing [45Ca]calcium chloride were brought to different levels of supersaturation with various concentrations of oxalate. The crystallization was assessed by measuring the amount of isotope remaining in solution 30 min after the addition of CaOx seed crystals to samples containing citrate in concentrations corresponding to those in final urine. The experiments were carried out both in pure salt solutions and in solutions with dialysed urine. Increased concentrations of citrate resulted in a reduced crystallization of CaOx in both the presence and absence of dialysed urine, but with the lowest rate of crystallization in the samples containing urine. The increased concentration of 45Ca remaining in solution reflected a reduced crystallization, which could possibly be explained both by a reduced supersaturation and by an increased inhibition of CaOx crystal growth. The direct effects of citrate on CaOx crystal growth were assessed by calculating the ion-activity product of CaOx (APCaOx) at corresponding degrees of crystallization. The APCaOx recorded at a 30% reduction of the amount of isotope in solution increased with increasing concentrations of citrate between 1.0 and 1.5 mmol/l samples both with and without dialysed urine. These findings indicate that citrate has a weak direct inhibitory effect on CaOx crystal growth, which adds to the reduced growth rate brought about by urinary macromolecules and a decreased supersaturation.

Antacids↗
PubMed1995

Clinical course and cystine stone formation during tiopronin treatment.

The formation of stones in patients with cystinuria can be counteracted by reducing the urinary concentration of cystine and by increasing its solubility. Thirty-one patients with homozygous cystinuria and treated with tiopronin (2-mercaptopropionylglycine) were followed for between 0.4 and 12 years (median 8.8). With the aim of avoiding cystine concentrations above 1200 mumol/l, the daily dose varied between 500 and 3000 mg (median 1500). The therapeutic effect was evaluated from the clinical symptoms and repeated radiographic examinations. The rate of stone formation during the treatment period was reduced by 60% in comparison with the pretreatment period (P < 0.001). The frequency of active stone removal was reduced by 72% (P < 0.05). The formation of new stones was associated with a higher cystine concentration than was the case during periods when stone formation and stone growth were excluded (P < 0.05). The probability of new stone formation increased with increasing concentrations of cystine up to 1100 mumol/l, but stone formation was not accentuated above 1200 mumol/l. There was no significant relationship between the 24 h excretion of cystine and stone formation. It is concluded that the formation of cystine stones can be efficiently counteracted during treatment with tiopronin, guided by analysis of the concentration of urinary cystine.

Adolescent↗
PubMed1995

Measurement of diurnal variations in urinary cystine saturation.

In an attempt to improve the diagnostic value of urine analysis in patients with homozygous cystinuria, we studied the diurnal variation in urine composition. A simplified estimate of the ion-activity product of cystine was used to increase the probability of identifying patients with a particular risk of stone formation. Eight 6-h urine samples were collected during two 24-h periods. The highest urinary excretion of cystine was recorded between 1200 and 1800 hours and the lowest between 0000 and 0600 hours, whereas the urinary cystine concentration was highest between 0000 and 0006 hours and lowest between 1200 and 1800 hours. The approximate ion-activity product of cystine had a maximal level between 0000 and 0600 hours but a minimal level between 0600 and 1200 hours. The differences between different periods were numerically more pronounced in terms of the ion-activity product of cystine than in terms of concentration. The peak concentrations of cystine in 6-h samples were about 90% higher than the corresponding concentrations in 24-h urine samples. It is concluded that the analysis of cystine in 6-h urine samples reveals transient episodes of cystine supersaturation that otherwise will remain undetected. Further studies are, however, needed to establish its usefulness in clinical practice.

Adult↗
PubMed1995

Technical tip: simple concept for minimizing problems with double-J stents with distal end at high level in ureter.

A procedure is described to avoid problems with stents that either have been inserted too far in the ureter or have migrated to a level above the bladder and to solve this problem easily if it nevertheless occurs. A knot is tied on the pulling thread at the end of the stent to create a loop of approximately 2 cm. With such a pre-caution, the loop usually remains in the bladder in case of limited stent retraction. For stents that retract to a higher level in the ureter, a special extraction device was constructed from a standard ureteral catheter. These two procedures have so far made it possible to easily remove or adjust the position of 13 of those 15 stents (87%) in 225 patients in whom the distal end became positioned proximal to the ureteral orifice. The procedure was in all cases undertaken without regional or general anesthesia and without the need for ureteroscopy.

Equipment Design↗
PubMed1995

Crystallization properties in urine from calcium oxalate stone formers.

PURPOSE: We determine whether stone formers and normal subjects can be distinguished in terms of supersaturation with calcium oxalate, and inhibition of calcium oxalate growth and aggregation. MATERIALS AND METHODS: An estimate of the ion activity product of calcium oxalate was obtained from the analysis of calcium, oxalate, citrate and magnesium in 16-hour urine samples obtained between 6 a.m. and 10 p.m. The inhibition of calcium oxalate crystal growth and aggregation was assessed in 8-hour urine specimens obtained between 10 p.m. and 6 a.m. RESULTS: The ion activity product of calcium oxalate was higher and inhibition of crystal aggregation was lower in stone formers than in normal subjects. Inhibition of crystal growth was lower only in male stone formers. Quotient 1 (10(2) x ion activity product of calcium oxalate/inhibition of crystal growth), quotient 2 (10(2) x ion activity product of calcium oxalate/inhibition of crystal aggregation) and quotient 3 (10(4) x ion activity product of calcium oxalate/[inhibition of crystal growth x inhibition of crystal aggregation]) were significantly higher in stone formers. CONCLUSIONS: The biochemical risk situation in calcium oxalate stone formers can be summarized by quotient 2 or 3.

Calcium Oxalate↗
PubMed1994

Investigation of single and recurrent stone formers.

A routine programme for investigation of patients with renal stone disease is presented. The different steps in this process are determined by the stone composition and the patient's previous history of stone formation. Assessment of the supersaturation and the crystallization properties are carried out in urine collected during a 24-hour period in one 16-hour and one 8-hour sample. The programme described in this paper has been formulated with a therapeutic goal in mind, whereby expensive and unnecessary procedures are avoided.

Calcium↗
PubMed1993

The effects of citrate and urine on calcium oxalate crystal aggregation.

The rate of crystal sedimentation in a suspension of calcium oxalate monohydrate (COM) crystals was determined spectrophotometrically in the presence and absence of dialysed urine and citrate. A reduced rate of crystal sedimentation after stirring was recorded in suspensions containing citrate in concentrations between 0.33 and 1.67 mmol/l. The sedimentation rate was reduced in the presence of a 0.3-3.3% concentration of dialysed urine, with increased inhibition of crystal sedimentation when the concentration of urine was increased. A comparison of the inhibition of COM crystal sedimentation in whole urine and in dialysed urine from normal subjects and stone-formers disclosed significantly higher values (P < 0.05) in the dialysed urine. The results support previous observations that physiological concentrations of citrate might efficiently inhibit the aggregation of COM crystals. Furthermore even low concentrations of both whole urine and dialysed urine are apparently very efficient inhibitors of COM crystal aggregation.

Calcium Oxalate↗
PubMed1993

Calcium phosphate: an important crystal phase in patients with recurrent calcium stone formation?

Stone and urine composition were analysed in 75 men and 40 women with recurrent calcium oxalate stone disease (group R) and in 48 men and 19 women who had formed only one calcium-oxalate-containing stone (group S). Patients who had developed stones with a large fraction of calcium phosphate were significantly more frequent in group R than in group S. There was furthermore a higher excretion of calcium and higher calcium oxalate supersaturation levels in patients with stones containing more than 25% calcium phosphate. It was concluded from these observations that the calcium phosphate content of renal stones might be a useful factor in predicting the future course of the disease.

Calcium↗
PubMed1993

Cutaneous anesthesia with lidocaine-prilocaine cream: a useful adjunct during shock wave lithotripsy with analgesic sedation.

A comparative randomized double-blind study between 99 patients with (group 1) and 100 without (group 2) cutaneous anesthesia with a lidocaine-prilocaine cream during extracorporeal shock wave lithotripsy (ESWL*) with an unmodified Dornier HM3 lithotriptor was done. The application of the anesthetic cream or a placebo preparation was used in addition to premedication with meperidine hydrochloride and diazepam. In case of pain experience additional doses of analgesic sedation were administered. The requirement of additional analgesic sedation at a generator voltage of 14 kv. was significantly higher in group 2 than in group 1 (42 versus 26 patients, p < 0.05). The ESWL treatment was completed with only premedication in 39% of the patients in group 2 compared with 50% in group 1. The pain experience at 14 kv. was significantly lower for male patients in group 1 (p < 0.01). The most pronounced difference between groups 1 and 2 was recorded during treatment of stones in the upper calices, whereby 22% and 79%, respectively, required additional analgesic sedation at a generator voltage of 14 kv. (p < 0.05). A less pronounced but still significant difference was also recorded at 14 kv. for patients with stones in the other parts of the kidney and ureter (p < 0.05). The maximal median energy settings in groups 1 and 2 were 15.9 kv. and 15.4 kv., respectively. There were 27 patients in group 2 and 18 in group 1 who were treated with a maximum of 14 kv. The overall requirement of additional analgesic sedation was 62% in group 2 and 51% in group 1. Cutaneous anesthesia with lidocaine-prilocaine cream obviously has clinically significant effects on pain experience during ESWL. It cannot replace the need for analgesic sedation but it can be used advantageously to reduce the dosage of analgesic and sedative drugs during ESWL treatments performed without regional or general anesthesia in the unmodified Dornier HM3 lithotriptor.

Administration, Cutaneous↗
PubMed1993

Anesthesia-free extracorporeal shock wave lithotripsy of distal ureteral stones without a ureteral catheter.

The therapeutic results of extracorporeal shock wave lithotripsy (SWL) for distal ureteral stones were compared between 70 patients treated without a ureteral catheter (Group 0) and 142 patients treated during a period when attempts always were made to pass the stone with a catheter before the treatment (Group UC). All SWL procedures were carried out with an unmodified Dornier HM3 lithotripter and with only analgosedation with pethidine (meperidine) and diazepam. One shock wave session was sufficient in 76% of the patients in Group 0 and in 77% of those in Group UC. There were no differences between the groups in terms of need for retreatment and the mean numbers of sessions were 1.37 +/- 0.79 (SD) in Group 0 and 1.28 +/- 0.61 in Group UC (P > 0.05). The stone-free rate after 4 weeks was 96% and 97%, respectively. This result was achieved without ureteral manipulations after SWL in 89% of the patients in Group 0 and in 95% of the patients in Group UC (P > 0.05). The number of shock waves and the energy index were lower in Group 0 than in Group UC (P < 0.001). Patients with distal ureteral stones apparently can be treated with SWL without a ureteral catheter with approximately the same success rate as with a catheter. The use of a catheter might, however, be of value for easy localization of scarcely radiopaque stones and possibly in some cases of seriously impacted stones, as well as for treatment of children, who regularly require general anesthesia.

Anesthesia↗
PubMed1993

Effects of citrate on the different phases of calcium oxalate crystallization.

Urinary citrate appears to be an important factor in the crystallization process of calcium oxalate and calcium phosphate. The urinary excretion of citrate was found to be significantly lower in patients with calcium oxalate stone disease as compared with normal subjects, and about 30 per cent of the calcium stone formers can be considered as hypocitraturic. The lowest excretion of citrate was recorded in urine collected during the night. Citrate has significant effects on supersaturation with respect to both calcium oxalate and calcium phosphate, it also inhibits the growth of these crystals. In addition, citrate appears to be capable of inhibiting the aggregation of crystals composed of calcium oxalate, brushite, and hydroxyapatite. The heterogenous growth of calcium oxalate on calcium phosphate is also counteracted by citrate. As a consequence of the crucial role of citrate in these processes, stone prevention with alkaline citrate has become an attractive form of treatment in patients with recurrent stone formation. Single evening dose administration of sodium potassium citrate resulted in an of sodium potassium citrate resulted in an increased excretion of citrate, reduced levels of the calcium/citrate ratio as well as supersaturation with respect to calcium oxalate and a decreased rate of stone formation. However, conflicting results of stone preventive treatment with alkaline citrate have been reported by different groups, and long-term follow-up of patients treated in a randomized way is necessary to definitely assess the efficacy of alkaline citrate.

Calcium Oxalate↗
PubMed1992

The effects of a single evening dose of alkaline citrate on urine composition and calcium stone formation.

The effects on urine composition and pH of a single evening dose of alkaline potassium sodium citrate were studied in healthy subjects and recurrent calcium oxalate stone formers. This treatment resulted in a prompt and significantly increased urinary pH with a duration until 10 a.m. the next day and a reduced risk of calcium oxalate crystallization between 10 p.m. and 10 a.m. In a retrospective study alkaline citrate was given in a single evening dose of 3.75 or 5 gm. to 55 patients with calcium oxalate stone disease and a total dose of 5.0 or 7.5 gm. was administered 2 or 3 times daily in 17 patients. The mean plus or minus standard deviation for duration of treatment was 3.5 +/- 1.7 years. Significantly reduced stone formation was recorded only in those on the evening dose regimen, which was associated with significant improvement of urine composition. Patients who continued to form new stones or who had growth of residual stones despite treatment also had improved urine composition but the calcium excretion and the calcium/citrate quotient remained elevated. In 4 patients with new stone formation calcium phosphate was the major component and calcium excretion was high but the concomitant increased citrate excretion resulted in a calcium/citrate quotient that was only slightly elevated. In patients forming calcium oxalate stones the only abnormality was a high calcium/citrate quotient. Because of favorable biochemical and clinical effects as well as good patient compliance with a single evening dose of alkaline citrate, this regimen appears to be an attractive alternative for long-term prevention of recurrent calcium stone formation.

Adult↗
PubMed1992

Calcium oxalate crystallization properties in urine with different specific electrical conductivities.

The relationship between the degree of urine dilution and the risk of calcium oxalate crystallization was studied in 32 urine samples collected from stone formers and normal subjects during an 8-hour period between 10 p.m. and 6 a.m., and in 4-hour urine samples collected during 24-hour periods from 6 patients with calcium stone disease. The risk of calcium oxalate crystallization was analyzed in terms of the increase in oxalate concentration required for a standardized precipitation of crystals of calcium oxalate. The degree of urine dilution was determined with a new instrument (urimho) designed for measuring the concentration, in terms of specific electrical conductivity, in urine samples of droplet size. With this device urine concentration can be expressed in urimho values between 1 and 5. There was a good correlation between recordings of specific electrical conductivity performed with the new device and with a conventional conductivity meter. There was a statistically significant positive correlation between urimho values and calcium oxalate crystallization. Calcium oxalate crystallization greater than 1.3 was not observed in any sample with a urimho value of 2 but it was noted in 31% of the samples with urimho values greater than 2. A positive relationship was also recorded between the urine pH and the urimho level, which is noteworthy because there was an inverse relationship between urine pH and calcium oxalate crystallization. A pH greater than 6 was observed in 78% of the samples with a urimho value of 2 but it was noted in only 27% of the samples with urimho readings between 3 and 5. A considerable variation in the response in urinary flow to ingested volumes was recorded. Therefore, monitoring of urine dilution by means of a sample device like the urimho might be of great help for patients with calcium stone disease in an effort to prevent recurrent stone formation by urine dilution, provided a urimho value of less than 3 can be maintained.

Calcium↗
PubMed1992

Extracorporeal shock wave lithotripsy of bile duct stones: a single institution experience.

Extracorporeal shock wave lithotripsy treatment with Dornier HM3 or MPL 9000 machines was applied in 37 patients with problematic bile duct stones. General anaesthesia was not required. After one extracorporeal shock wave lithotripsy session 14/37 patients (38%) were spontaneously stone free, and additional endoscopic extraction (eight of 37) and retreatments with extracorporeal shock wave lithotripsy (seven cases) increased the stone free rate to 29/37 (78%). In three patients with intrahepatic stones, the bile ducts could not be evaluated decisively at cholangiography and ultrasonography, but they were all symptom free at 15 to 38 months follow up. If these three patients are added to the radiologically stone free patients, the overall clinical success rate was 32/37 (86%). There were no serious complications, hospital admissions, or 30 day mortality as a result of extracorporeal shock wave lithotripsy or endoscopic procedures. It is concluded that extracorporeal shock wave lithotripsy is a valuable adjunct to the non-surgical treatment of bile duct stones.

Aged↗