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

Summary 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.     

Clinical significance of phosphaturia

From September 1986 to August 1987, heavy precipitation of amorphous calcium phosphate, that is phosphaturia, was found at our outpatient clinic in 153 postprandial urine specimens from 115 patients, in 1.5% of all the specimens examined during this period. One patient was excluded because he had both urolithiasis and urinary tract infection. The remaining 152 specimens with phosphaturia were then divided into 3 groups; Group I from patients with urolithiasis, Group II from patients with urinary tract infection and Group III from patients without either urolithiasis or urinary tract infection (Phosphaturia Group, Table 1). It is evident from this table that phosphaturia is repeated more frequently in patients with urolithiasis than in patients without urolithiasis (p less than 0.01). 200 urine specimens examined during this period were selected randomly. Three bloody or purulent specimens were excluded. The remaining 197 specimens from 189 patients were divided into 3 groups, as in the phosphaturia group (Control Group, Table 2). When the proportion of the number of specimens to the total is compared between the phosphaturia group and the control group, it is clear that phosphaturia is found more frequently in specimens from patients with urolithiasis than in specimens from patients without urolithiasis (p less than 0.01). Since phosphaturia was almost always found in the specimens with urine pH greater than or equal to 7, 486 patients, in whom the pH of the first urine specimen was equal to or above 7, were selected from among 1434 patients undergoing urinalyses during this period and divided into 3 groups as has been described above (Table 3).(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of sociodemographics in the occurrence of orthopaedic trauma

IntroductionWe sought to determine the effects of sociodemographic factors on the occurrence of orthopaedic injuries in an adult population presenting to a level 1 trauma center.Materials and methodsWe conducted a retrospective chart review of patients who received orthopaedic trauma care at a level 1 academic trauma center.Results20,919 orthopaedic trauma injury cases were treated at an academic level 1 trauma center between 01 January 1993 and 27 August 2017. Following application of inclusion/exclusion criteria, a total of 14,654 patients were retrieved for analysis. Out of 14,654 patients, 4602 (31.4%) belonged to low socioeconomic status (SES), 4961 (32.0%) to middle SES and 5361 (36.6%) to high SES. Following adjustment for age, sex, race, insurance status and injury severity score (ISS), patients belonging to middle SES vs. low SES (OR 0.77 [95% CI 0.63-0.94]; p = 0.009) or high SES vs. low SES (OR 0.77 [95% CI 0.62-0.95]; p = 0.016) had lower odds of receiving a penetrating injury as compared to a blunt injury.ConclusionThe results from this study indicate that a link exists between sociodemographic factors and the occurrence of orthopaedic injuries presenting to a level 1 trauma center. The most common cause of injury varied within age groups, by sex, and within the different socioeconomic groups.     

The effect of pH on the risk of calcium oxalate crystallization in urine

The risk of calcium oxalate (CaOx) crystallization at different pH levels was determined in urine from recurrent CaOx-stone formers and normal subjects. The highest crystallization risk was observed between pH 4.5 and 5.5. In the pH range 6.5-7.5, there was a marked increase in crystallization of calcium phosphate (CaP). The results suggest the beneficial effect of moderate alkalinization in terms of a reduced CaOx crystallization. Reduced CaOx crystallization occurs at the expense of an increased formation of CaP crystals. Whether this increases the risk of CaP-stone formation is not known, but the CaP crystals were usually small, at least below pH 7.5.     

Fasting versus 24-h urine pH in the evaluation of nephrolithiasis

An abnormal urinary pH (UpH) represents an important risk factor for nephrolithiasis. In some stone formers, a fasting urine specimen is obtained instead of a 24-h urine collection for stone risk evaluation. We examined the relationship between 24-h and fasting UpH in non-stone forming individuals and stone formers with various etiologies and a wide range of urine pH to test the validity of fasting UpH. Data from 159 subjects was examined in this retrospective study. We included non-stone forming subjects and stone formers with hypercalciuria, distal renal tubular acidosis, idiopathic uric acid nephrolithiasis, or chronic diarrhea. Participants collected a 24-h urine followed by a 2-h fasting urine. For the entire cohort, a significant correlation was seen between fasting and 24-h UpH (r ² = 0.49, p < 0.001). Fasting pH was significantly higher than 24-h UpH for the entire cohort (6.02 ± 0.63 vs. 5.89 ± 0.51; p < 0.001), and in the subgroups of non-stone formers and stone formers with hypercalciuria or distal renal tubular acidosis. Fasting UpH was >0.2 pH units different from 24-h UpH in 58% of participants. The difference between fasting and 24-h UpH did not correlate with net gastrointestinal alkali absorption or urine sulfate, suggesting that dietary factors alone cannot explain this difference in UpH. Fasting urine pH correlates moderately with 24-h urine pH in a large cohort of individuals. Significant variability between these two parameters is seen in individual patients, emphasizing the cardinal role of 24-h urine collection for evaluating UpH in nephrolithiasis.     

The role of pH in altering serum ionized calcium concentration

Although parathormone primarily determines normal ionized serum calcium concentration [Ca++] over the long term, it has little impact in the acute situation. Nonhormonal changes in [Ca++] have been related to acute changes in serum pH, but these have been believed small. With use of an experimental model of acute pancreatitis, we measured changes in [Ca++] and related them to changes in other serum constituents known to affect it. All 18 animals studied experienced a decrease in total serum calcium concentration [CaT]. Changes in [CaT] correlated only with changes in protein-bound calcium concentration [CaP] (r = 0.98, p less than or equal to 0.0005). They did not correlate independently with changes in albumin, globulin, or total protein concentration. [CaP] varied as a function of albumin, globulin, and phosphate concentration and pH according to the equation: [CaP] = 17.9 +/- 0.89 [albumin] = 0.68 [globulin] - 2.5 pH + 0.12 [phosphate]. Calculated values for [CaP], when this equation was used, correlated strongly with observed values for [CaP] (r = 0.81, p less than or equal to 0.0005). Measured [Ca++] increased in the animals early during pancreatitis and then returned to baseline levels. A few animals experienced ionized hypocalcemia. [Ca++] correlated only with changes in pH (r = 0.87, p less than or equal to 0.02). The calculated response slope was delta [Ca++]/delta pH = -2.9. It is concluded that pH has a greater effect on [Ca++] than previously recognized. The major determinant of [CaT] during periods of rapid physiologic change appears to be [CaP] while that for [Ca++] is pH.     

The effect of pH and urine dilution on the electrophoretic mobility of uric acid crystals

As a result of a continuing programme to understand better the uric acid stone treatment and prophylaxis, an investigation of the effect of pH and urine dilution on the surface charge of uric acid crystals was undertaken. A microelectrophoretic technique was employed to characterize the nature of the surface charge and the electrokinetics of uric acid crystals both in natural and synthetic urines under different conditions of pH and dilution. Both dilution and alkalization reduced the specific conductance of urine and increased the electrophoretic mobility (zeta potential) of uric acid crystals. The presence of cationic additives in diluted urine altered the zeta potential of uric acid crystals. Such findings suggest that proper control of the pH level and urine dilution as well as the surface charge at the solid-liquid interface represent an important factor in the uric acid stone prophylaxis.     

The role of urine cytology in the assessment of lower urinary tract symptoms.

OBJECTIVE: To evaluate the role of urine cytology in the investigation of men with lower urinary tract symptoms (LUTS) in the absence of haematuria. PATIENTS AND METHODS: The study comprised 336 men attending a LUTS assessment clinic, who had neither macroscopic nor microscopic haematuria. One sample of urine was collected for cytology. Those with suspicious urine cytology were investigated with intravenous urography and cystoscopy. RESULTS: Five men had abnormal urine cytology results; on further investigation one of them was found to have carcinoma in situ (CIS) and one to have a transitional cell carcinoma. Three had false-positive urine cytology results. CONCLUSION: A bladder tumour or CIS was detected in 0.6% of the population tested. The cost per cancer diagnosed was GB pound 2020. Urine cytology is a simple noninvasive way of assisting accurate diagnosis of men who have LUTS in the absence of haematuria.     

The role of luminal pH in production of gastrin cell hyperplasia in the rat

Truncal vagotomy is associated with diminished gastric acid production, gastrin cell hyperplasia, and elevated serum gastrin levels. To study the role of reduced antral luminal acidity in the production of gastrin cell proliferation, gastrin cell densities were quantitated in preparations involving exposure of the antral mucosa to a non-acid lumen at different levels of the gastrointestinal tract. Female Sprague-Dawley rats were divided into the following experimental groups: intact controls, shams, antral diverticulum on the jejunum, antral diverticulum on the ileum, and antral diverticulum on the colon. At death, 2 weeks, 2 months, and 6 months after operation, luminal pH was at least 5.8 for each group of rats with antral diverticula. No significant changes in gastrin cell numbers were observed in rats with jejunal or ileal diverticula. For those animals with colonic diverticula, gastrin cell counts were increased 55% at 2 weeks (503 +/- 23 cells per cm versus 320 +/- 13 cells per cm for shams). At 2 months gastrin cell numbers had increased further (639 +/- 54 cells per cm) in rats with antral diverticula on the colon. Gastrin cell proliferation was sustained at 6 months in this group. A factor other than reduced luminal acidity induces gastrin cell proliferation in antral mucosa exposed to colonic content. The responsible agent is not present in the small-bowel lumen. A non-acid luminal environment is not, by itself, a sufficient stimulus for gastrin cell hyperplasia.     

前列腺增生症病人的逼尿肌收缩力减弱与剩余尿

应用压力流率测定技术，经Ｓｃｈ¨ａｆｅｒ列线图和直线被动尿道阻力关系（ＬｉｎＰＵＲＲ）定量分析９５例前列腺增生症病人的逼尿肌收缩强度。逼尿肌收缩强度分为四级：很弱（ＶＷ）、弱（Ｗ）、正常（Ｎ）和强（ＳＴ）。导管法结合压力流率测定时膀胱灌注量与排出量之差确定剩余尿。结果表明，逼尿肌收缩力很弱和弱与收缩力正常和强的病人之间存在显著性差异（Ｐ＜０．００１）。剩余尿量随逼尿肌收缩力减弱而增加。逼尿肌收缩力很弱的病人术后剩余尿量未改善；逼尿肌收缩力弱的病人术后逼尿肌收缩力可能改善，剩余尿减少；逼尿肌收缩力正常或强的病人术后剩余尿明显减少。