Biomedical subjects

P C Hallson

Publications and source records attributed to P C Hallson.

6 recordsLinked to original sources

PubMed1979

Uromucoids and urinary stone formation.

Crystal formation was studied in fresh urine samples after rapid concentration to standard osmolarity in a rotary evaporator at 37 degrees C. Uromucoids promoted calcium oxalate and calcium phosphate crystal formation and also induced clustering of calcium phosphate precipitates. It is postulated that uromucoid precipitation is the first stage in stone formation. Minerals then deposit on the uromucoid precipitate and the whole complex becomes attached to the renal tubules.

Calcium Oxalate↗

PubMed1978

A new urinary test for stone "activity".

Rapid evaporation of urine to osmolarity 1200 results in a high incidence of envelope Wedellite and calcium phosphate crystals. The Wedellite crystals closely resemble those seen in untreated urine samples of stone formers. The incidence of crystalluria produced by these tests is higher in the stone formers than in the normal subjects, reduced by thiazides and increased by cellulose phosphate; combined thiazide and cellulose phosphate therapy was most effective in reducing crystalluria. Simple calcium and oxalate concentration products were calculated and did not correlate well with incidence of calcium oxalate crystalluria. Although the product is important, inhibitors of crystal formation must be equally important. It is postulated, but not proven, that the evaporation tests may indicate normal subjects at risk to stone formation when exposed to chronic dehydration and whether a stone former is still metabolically active.

Benzothiadiazines↗

PubMed1977

Seasonal variations in urinary crystals.

Individual urine samples from normal subjects and stone-formers with idiopathic hypercalciuria have been examined for crystals both qualitatively and quantitatively at 37 degrees C. The group as a whole showed a rise in incidence of urinary crystals in the summer months of June to August inclusive. This rise was seen most clearly in overnight urines, collected on rising in the morning, and the patients appeared to be at risk overnight during the summer. In the untreated patients the summer rise in incidence of phosphate crystals was quite dramatic but was only small in the cellulose phosphate treated group, who showed a rather constant and raised incidence of oxalate crystals right through the year. Seasonal crystal incidence has been compared with seasonal changes in urinary composition. The rise in crystal incidence during the summer was associated with increased creatinine concentration in the same urine samples and with increased oxalate concentration in 24-hour urine collections.

Crystallization↗

PubMed1977

Seasonal variations in urinary excretion of calcium and oxalate in normal subjects in patients with idiopathic hyperclaciuria.

A longitudinal 9-year retrospective study of 24-hour urinary calcium values has been made in a metabolic stone clinic amongst patients with idiopathic hypercalciuria. No seasonal variations could be observed in contrast ot a previous study from Leeds, A prospective longitudinal study was made of 24-hour urinary calcium values in a small group of normal subjects. No seasonal variation could be ovserved. In the prospective study no seasonal variations in urinary oxalate could be observed. In a 2-year longitudinal study of stone patients with idiopathic hypercalciuria, urinary oxalate was found to be higher in the summer than in the winter. This was attributed to the combination of a higher intake of oxalate-rich foods in the summer, and the low calcium diet with which they were treated.

Calcium↗

PubMed1976

Urinary oxalate in summer and winter in normal subjects and in stone-forming patients with idiopathic hypercalciuria, both untreated and treated with thiazide and/or cellulose phosphate.

Urinary oxalate excretion has been measured by a specific enzymatic method in normal subjects and stone formers with idiopathic hypercalciuria. In every group studied urinary oxalate was higher in the summer than in the winter. These differences were slight and not significant in normal subjects but were considerable and statistically significant in the stone formers both untreated and when treated with thiazide. Thiazides raise urinary oxalate only very slightly but cellulose phosphate leads to large rises in urinary oxalate both in the summer and the winter. The highest values of urinary oxalate were seen in the summer in patients treated with cellulose phosphate. The mean rise in this group was 70% above normal and this must be viewed with some anxiety.

Benzothiadiazines↗

PubMed1976

Crystalluria in normal subjects and in stone formers with and without thiazide and cellulose phosphate treatment.

Quantitative and qualitative studies have been made of the urinary crystals from a series of normal subjects and from stone formers with idiopathic hypercalciuria with and without treatment with thiazide diuretics and/or cellulose phosphate. The results obtained from mid-morning unprepared subjects seemed more helpful than those obtained following overnight collections or after a dry breakfast. Crystalluria was more common in stone formers than in normal subjects, but was seen in both groups. The most striking difference between these 2 groups was the almost complete absence of aggregation of oxalate crystals in the normal subjects. Cellulose phosphate greatly reduced phosphate crystals but resulted in a large increase in small oxalate crystals but without change in the incidence of aggregation of oxalate crystals. Thiazides also reduced occurrence of phosphate crystals but only gave a very small increase in oxalate crystals and also without change in aggregation of oxalate crystals.

Adult↗