Discovery of urinary biomarkers

A myriad of proteins and peptides can be identified in normal human urine. These are derived from a variety of sources including glomerular filtration of blood plasma, cell sloughing, apoptosis, proteolytic cleavage of cell surface glycosylphosphatidylinositol-linked proteins, and secretion of exosomes by epithelial cells. Mass spectrometry-based approaches to urinary protein and peptide profiling can, in principle, reveal changes in excretion rates of specific proteins/peptides that can have predictive value in the clinical arena, e.g. in the early diagnosis of disease, in classification of disease with regard to likely therapeutic responses, in assessment of prognosis, and in monitoring response to therapy. These approaches have potential value, not only in diseases of the kidney and urinary tract but also in systemic diseases that are associated with circulating small protein and peptide markers that can pass the glomerular filter. Most large scale biomarker discovery studies reported thus far have used one of two approaches to identify proteins and peptides whose excretion in urine changes in specific disease states: 1) two-dimensional electrophoresis with mass spectrometric and/or immunochemical identification of proteins and 2) top-down mass spectrometric methods (SELDI-TOF-MS and capillary electrophoresis-MS). These studies have been chiefly in the areas of nephrology, urology, and oncology. We review these applications, focusing on two areas of progress, viz. in bladder cancer and in acute rejection of renal transplants. Progress has been limited so far. However, with the advent of powerful LC-MS/MS methods along with methods for quantifying LC-MS/MS output, there is hope for an accelerated discovery and validation of disease biomarkers in urine.     

Use of urinary gram stain for detection of urinary tract infection in childhood

In this study, urinary culture, urinary Gram stain, and four tests within the urinalysis, leukocyte esterase, nitrite, microscopyfor bacteria, and microscopyforpyuria, were examined in 100 children with symptoms suggesting urinary tract infection. Our purpose was to determine the validity of the urinary Gram stain compared with a combination of pyuria plus Gram stain and overall urinalysis (positiveness of nitrite, leukocyte esterase, microscopy for bacteria, or microscopy for white blood cell). Of 100 children, aged two days to 15 years, 70 (70 percent) had a positive urinary culture: 40 girls (57 percent) and 30 boys (43 percent). Escherichia coli was the most common isolated agent. The sensitivity and specificity of the urinary Gram stain were 80 percent and 83 percent, and that of the combination of pyuria plus Gram stain 42 percent and 90 percent, and that of the overall urinalysis 74 percent and 3.5 percent respectively. Our findings revealed that neither method of urine screen should substitute for a urine culture in the symptomatic patients in childhood.     

Drug-induced urinary calculi

Urinary calculi may be induced by a number of medications used to treat a variety of conditions. These medications may lead to metabolic abnormalities that facilitate the formation of stones. Drugs that induce metabolic calculi include loop diuretics; carbonic anhydrase inhibitors; and laxatives, when abused. Correcting the metabolic abnormality may eliminate or dramatically attenuate stone activity. Urinary calculi can also be induced by medications when the drugs crystallize and become the primary component of the stones. In this case, urinary supersaturation of the agent may promote formation of the calculi. Drugs that induce calculi via this process include magnesium trisilicate; ciprofloxacin; sulfa medications; triamterene; indinavir; and ephedrine, alone or in combination with guaifenesin. When this situation occurs, discontinuation of the medication is usually necessary.     

Serum and urinary immunoglobulin in the rat model of acute urinary tract infection

Total levels of urine and serum immunoglobulin IgM, IgG and IgA, and the E. coli-specific bacterial immunoglobulin response were determined by enzyme-linked immunosorbent assay (ELISA) in a rat model of acute urinary tract infection. High levels of urinary IgM were detected as early as day 3 post infection and then decreased to statistically insignificant levels. Peak levels of IgG occurred in the serum and urine on day 14. Urine and serum IgA levels remained low throughout the study period. The results demonstrate that in the rat model of acute urinary tract infection, IgM appears first in the urine and serum, and rapidly decreases. IgG then appears in the serum and urine followed by a late E. coli-specific immunoglobulin serum and urine response. Also, a non-specific component of the immunoglobulin response was noted in both the serum and urine. In the rat, IgA appears to play little or no role in the urine or in the serum response to the infection.     

The systematic histologic elaboration of urinary bladders with different pathologic findings (urinary bladder carcinoma, tumor-free aging urinary bladders)

We report our systematic histological examinations of 16 urinary bladders (11 bladders with cancer, 5 bladders was tumour-free). All residual tumour-free portions in bladder with multiple or solitary cancers demonstrated various precancerous variations of urothelium, not only near the tumours. In 1 urinary bladder among 5 from elder patients, we diagnosed a clinically undetected cancer. In a few cases, we correlated histological examinations with graphical demonstration (through a computer) of the exophytic tumour portions. Our results agree with individual therapy of urinary bladder cancer.     

Modern use of urinary antiseptics

Recent experimental evidence suggests that hydrocortisone (Kendall's Compound F) is probably the principal glycogenic steroid secreted by the adrenal cortex and that under conditions of stress it may participate more than cortisone in physiologic reactions. Laboratory studies indicate that hydrocortisone has greater physiologic activity, milligram for milligram, than cortisone and with certain assays its potency is twice as great.Two forms of hydrocortisone, the free alcohol preparation and the acetate, were given systemically to patients with rheumatoid arthritis and were observed to possess significant differences in ability to suppress the disease manifestations. When administered orally in large initial doses, hydrocortisone (free alcohol) appeared to produce greater suppressive effects, milligram for milligram, than either hydrocortisone acetate or cortisone acetate. Comparisons of potency made by determining maintenance dosage requirements for equivalent degrees of clinical control in the same patients indicated that the effectiveness of hydrocortisone (free alcohol) is more than 50 per cent greater than that of either the free or acetated forms of cortisone and approximately twice as great as that of hydrocortisone acetate. Certain observations suggested that the greater antirheumatic activity of hydrocortisone (free alcohol) is not accompanied by a correspondingly greater tendency toward endocrine complications. If more extensive future investigations support this observation, hydrocortisone (free alcohol), by producing equally efficient results with smaller doses, may prove superior to cortisone as a therapeutic agent.Intra-articular injections of hydrocortisone acetate appear to have only a limited place in the management of rheumatoid arthritis but may be used for temporary relief under certain conditions. In preliminary studies by the author it was noted that whereas improvement resulted in 80 per cent of the treated joints, the improvement was graded as pronounced or very pronounced in only one-half of the joints so injected. In almost all instances the benefits derived were quite temporary. Results observed in treatment of osteoarthritic joints by this method were decidedly poorer than in rheumatoid arthritis.     

Maturation of urinary proteoglycan excretion

Urinary proteoglycan excretion was studied using two newly established methods in subjects aged between 1 and 22 years. Analysis of glycan moieties showed an age-dependent decrease from 9.1±5.5 (SD) g/mol creatinine (n=5) at the age 1–6 years to 1.9±1.3 (n=5,P<0.01) in those aged 16–22 years. Marked qualitative changes in the proteoglycan electrophoretic pattern occurred during the first and second years of life. Two major proteoglycan bands with a molecular weight of 50 kDa decreased in intensity so that the pattern resembled the adult configuration after 6 years of age. The latter consisted of a major band with a molecular weight of 80–100 kDa, the bands corresponding to a molecular weight of 50 kDa and lighter bands of molecular weight around 32 kDa. These changes may be related to functional maturation of the kidney as a whole and to an increase in the number of mature nephrons.