Urine Of Healthy People Research Articles

Abnormal urinary loss of vitamin C in diabetes: prevalence and clinical characteristics of a vitamin C renal leak

Diabetes is associated with low plasma vitamin C concentrations. We investigated the contribution of dysregulated vitamin C renal physiology, its prevalence, and associated clinical characteristics. An essential prerequisite was determination of normal vitamin C renal threshold, the plasma concentration at which vitamin C first appears in urine. Using data from 17 healthy participants who underwent vitamin C depletion-repletion studies with a vitamin C dose range of 15-1250mg daily, renal threshold was estimated using physiology-based pharmacokinetics modeling. Applying renal threshold 95% CIs, we estimated the minimal elimination threshold, the plasma concentration below which no vitamin C was expected in urine of healthy people. Renal leak was defined as abnormal presence of vitamin C in urine with plasma concentrations below the minimal elimination threshold. Criteria were tested in a cross-sectional cohort study of individuals with diabetes (82) and nondiabetic controls (80) using matched plasma and urine samples. Vitamin C renal thresholds in healthy men and women were [mean (SD)] 48.5 (5.2) µM and 58.3 (7.5) µM, respectively. Compared with nondiabetic controls, participants with diabetes had significantly higher prevalence of vitamin C renal leak (9% compared with 33%; OR: 5.07; 95% CI: 1.97, 14.83; P<0.001) and 30% lower mean plasma vitamin C concentrations (53.1 µM compared with 40.9 µM, P<0.001). Fasting plasma glucose, glycosylated hemoglobin A1c, BMI, micro/macrovascular complications, and protein/creatinine ratio were predictive of vitamin C renal leak. Increased prevalence of vitamin C renal leak in diabetes is associated with reduced plasma vitamin C concentrations. Glycemic control, microvascular complications, obesity, and proteinuria are predictive of renal leak.

Nanoconfinement effect based in-fiber extraction and derivatization method for ultrafast analysis of twenty amines in human urine by GC-MS: Application to cancer diagnosis biomarkers’ screening

Amines, including amino acids and biogenic amines are widely recognized as cancer biomarkers for early diagnosis and treatment. But rapid analysis of amines in biological samples with high sensitivity, good durability and low cost is still challenging. Herein, we proposed an ultrafast biological sample preparation method based on in-fiber extraction and derivatization using a homemade needle-tip devise. Under the nanoconfinement effect, the extraction was completed within 2 min in nanofibers, followed by the in-suit derivatization within 3 min under room temperature using pentafluoropropionic anhydride (PFA) as derivatization reagent, then the needle was inserted into the inlet of GC-MS directly for thermal desorption to enable the complete injection. Additionally, the established sample preparation strategy consumed only 20 μL organic solvent and urine sample, and the sensitivity was increased compared with other methods. After systematical optimization and validation, coupled to GC-MS, the established method was successfully applied to quantify twenty amines in urine of healthy people and lung, colorectal and breast cancer patients. The diagnosis biomarkers for each cancer were screened out and accessed by multiple statistical approaches. Then we further constructed the cancer diagnosis model of each cancer through binary logistic regression analysis for clinical use. Taken together, the established nanoconfinement effect based in-fiber extraction and derivatization biological sample preparation strategy in combination with GC-MS was an ultrafast method for biological analysis with high sensitivity, good durability, little organic solvent consumption and low cost. It possesses great potential in clinical cancer screening and treatment.

Chemical tools to monitor bladder cancer progression

Background Bladder cancer (BCa) is the most common cancer of the urinary system. Due to its high incidence and recurrence, as well as limited progress in the effective treatment, BCa is a challenge for today's medicine. Materials and Methods We used a set of chromogenic substrates to differentiate between the stages of bladder cancer progression (G1 (n = 10), G2 (n = 10), G3 (n = 10)). The proteolytic activity in individual the urine samples was determined by absorbance measurements. Then inhibitors of particular classes of enzymes were used to determine which enzymes dominate at a given stage of the neoplastic disease. Results The specific activity of enzymes in the urine of patients with confirmed bladder cancer was determined separately for three (G1, G2, G3) stages of the disease development. What is more, no activity was observed in urine of healthy people (n = 10). Discussion Research shows that specific enzymes are associated with the development of specific stages of cancer. We suspect that the differences in the proteolytic activity of urine samples are due to the presence of a different set of enzymes that are directly related to the particular stage of the disease. Conclusion We obtained three substrates for monitoring individual stages of bladder cancer development.

Virus in the Urine of Healthy People and Patients with Infectious Diseases

Virus in the Urine of Healthy People and Patients with Infectious Diseases

Clinimetallomics: Arsenic Speciation in Urine from Patients With Arsenism by HPLC-ICP-MS

Clinimetallomics is proposed as a branch of metallomics that focuses on the study of the metallome in clinical samples of urine, blood, and tissues. As the clinical diagnosis of arsenic poisoning is mainly based on the concentration of total arsenic in urine, the toxicity of arsenic varies greatly in different speciation. Analysis of arsenic speciation with excessive total arsenic in urine can provide a basis for precise treatment. It can also be used to understand the fate of arsenic in the body of patients with arsenic poisoning after treatment with sodium dimercaptopropane sulfonate. In this study, a HPLC-ICP-MS method was established for the determination of arsenic species in urine samples from patients diagnosed with arsenism. Use the established method to detect urine samples, which can be directly assayed after simple sample dilution with 20 mmol/L EDTA-2Na. With the concentration of arsenic speciation in the range of 1.0~100.0 ng/mL, the linear correlation coefficient was higher than 0.99996. The recoveries were between 92.4% and 109.0%. The precision of the concentration and retention time (n = 3) were less than 3.0% and 0.3%, respectively, and the detection limit was between 1.42 ng/mL and 1.86 ng/mL. This method can be applied to arsenic speciation in the urine of healthy people, in patients treated for arsenic poisoning, and in patients diagnosed with arsenism.

Diagnosis Based on Detection of CXCL10 in Urine as Biomarker for The Determining Diagnosis of Active Lung Tuberculosis

Tuberculosis diagnosis is an important component in decreasing TB incidence and prevalence. Because of the difficulty to collect sputum in some cases, urine specimens are used as it is easier to garner. One of the biomarkers in urine that can be used to diagnose pulmonary TB is IP-10, which can be represented by the CXCL10 gene. The study aims to determine the accuracy of diagnosis based on detection of the CXCL10 gene in urine as a biomarker for the patients with suspected pulmonary TB in Dr. Soetomo Hospital in Surabaya from November 2019 until March 2020. Thus, this is an observative laboratory research with a cross-sectional study. CXCL10 gene was examined using PCR for 36 urine samples, and then, the data, together with the medical records of clinical manifestations of pulmonary TB, GeneXpert MTB /RIF, blood count, and thorax radiograph, were processed using IBM SPSS Statistics 26. The results of the GeneXpert MTB/RIF and thorax radiograph criteria show positive results of pulmonary TB, which were 44.4% and 69.4% respectively. CXCL10 gene was not found in all urine of healthy people (negative), while 2.8% (1/36 samples) positive CXCL10 gene was found in a patient with positive GeneXpert, also with negative clinical manifestations and urine culture. In this study, the accuracy of diagnosis based on detection of the CXCL10 gene in urine for diagnosis of active pulmonary TB was 2.8%. Future research is needed to improve the methods, among them are bigger size of urine samples and clearer medical history of patients.

Recognition of urinary N-linked glycopeptides in kidney cancer patients by hydrophilic carbohydrate functionalized magnetic metal organic framework combined with LC-MS/MS.

A hydrophilic carbohydrate functionalized magnetic metal organic framework (Mag Zr-MOF@G6P) was synthesized via a facile one-step modification strategy for selective glycopeptide capture in virtue of hydrophilic interaction chromatography technique. The inherently hydrophilic Zr-MOF layer not only provides selective size-sieving pore structures but also offers large specific surface area to afford abundant affinity sites. Hydroxyl-rich glucose-6-phosphate was immobilized onto the Zr-MOF via a straightforward coordination manner to regulate its surface property, for the purpose of enhancing its hydrophilicity. Benefitting from the merits of Zr-MOF and glucose-6-phosphate, the as-designed composite exhibits good selectivity (the mass ratio of HRP digests to BSA digests was up to1:200) and low limit of detection (0.1fmolμL-1) towards the recognition of glycopeptides from standard samples. More excitingly, glycopeptides in urine of healthy people and patients with kidney cancer were successfully enriched and identified by the combined liquid chromatography-mass spectrometry/mass spectrometry technology (LC-MS/MS). Further gene ontology analysis of molecular function and biological process revealed that 13 original glycoproteins of the identified glycopeptides from urine of patients significantly participate in diverse cancer-associated events, including collagen binding, immunoglobulin receptor binding, antigen binding, and complement activation process. Graphical abstract.

Implementation of a Hplc Method for the Evaluation of Urinary 4-Hydroxyphenylacetic Acid in Patients with Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are a group of neoplasms that originate from neuroendocrine cells. They can occur in various anatomic locations, most commonly in gastro intestinal tract, lungs and pancreas. In NETs associated to the carcinoid syndrome, the tumor cells produce hormones, such as serotonin. 5- Hydroxyindoleacetic acid (5-HIAA), the main metabolite of serotonin, represents an useful urinary biomarker which is routinely determined to investigate and monitor patients with carcinoid syndrome by high performance liquid chromatography (HPLC). The chromatographic profile obtained by a standardized commercial HPLC method shows also the presence of 4-hydroxyphenylacetic acid (pHPAA), which is physiologically excreted in urine of healthy people. Interestingly, in some NETs profiles we observed a high pHPAA peak that was not resolved from 5-HIAA peak at higher concentrations of one or both metabolites. Therefore, we implemented and validated a HPLC method for the determination of urinary pHPAA improving the chromatographic separation between 5-HIAA and pHPAA. In addition, we determined pHPAA levels in 40 urine samples from patients with NETs that resulted significantly higher compared to healthy subjects. Our preliminary results showed that the modified HPLC method allows to quantify accurately pHPAA that could represent a useful marker, together with 5-HIAA, for the management of patients with NETs.

Вирусурия как составляющая микробиоты мочи и ее значение для оценки состояния здоровья мочевого тракта: описательное клиническое исследование

To determine the frequency of occurrence of oportunistic pathogenic bacterial flora and viral pathogens in the urine of healthy people with the establishment of the association between them. 40 healthy sexually active women and men were examined, which are divided by gender into equivalent groups: Group I - healthy women (n=19), Group II - healthy men (n=21). The age of the subjects ranged from 20 to 25 years, the average age was 22.4+/-1.2 years. In both groups, the average portion of morning urine was taken for a study after a proper hygienic procedure with self-urination of the subjects in a sterile plastic container (Sterile Uricol for urine sample collection "HiMedia"). In addition to the nutrient media regulated by the Clinical Guidelines, additional HiMedia chromogenic media were used to cultivate facultative anaerobic (FAB) and non-clostridial anaerobic bacteria (NAB). Detection of viruses was performed by PCR with detection in "real time". DNA isolation was carried out by the sorption method using the AmpliPrime DNA-Sorb-B ("NextBio") kit from urine samples, with preliminary concentration. In all 40 cases, normative leukocyturia was detected in the urine. According to the results of bacteriological examination of urine, healthy men and women in all cases found aerobic-anaerobic associations. Coagulase-negative staphylococci (CNS) and Corynebacterium spp. Dominated in the cluster of aerobic taxa of microbiota. (75.0%, 55.0% respectively). The spectrum of CNS was represented by five species: S.epidermidis (30.0%), S.haemolyticus (27.5%), and S.warneri (25.0%), S.saprophyticus and S.lentus (15.0%). Enterococcus spp. were recorded in the urine in 32.5% of cases. Representatives of the Enterobacteriaceae family were represented by 4 taxa: E. coli (10.0%), Klebsiella spp., Proteus spp. (5.0% each), Enterobacter spp., Citrobacter spp. (2.5%). In a cluster of anaerobic bacteria in the urine, Eubacterium spp. (60.0%) and almost half of healthy individuals recorded Lactobacillus spp. and Peptococcus spp. (42.5% each). When analyzing the frequencies of detection of various microbiota taxa, it was found that women significantly more frequently recorded urine Corynebacterium spp., Eubacterium spp. and Lactobacillus spp., as well as Enterococcus spp. and Peptococcus spp. Peptostreptococcus spp. and Veillonella spp. were significantly more often determined (p<0.05) in the urine of men. HHV6 (10.0%), HPV18 and B19 parvovirus (2,5%) were determined in the urine of healthy people. It should be noted that the studied viruses were more often recorded in men, in particular, HPV18 and parvovirus B19 - only in men, and HHV6 more often in men (7.5%), less often in women (2.5%). Significant associations of some genera of microorganisms with the sex of the participants were revealed for E. faecalis and Lactobacillus spp., which were more often found in the urine of healthy women Reliably significant associations were found for three taxa: viruses HPV6, HPV18 and parvoviruses B19 (16.7%) were determined in the presence of Bacteroides spp., Bifidobacterium spp., and Prevotella spp., in urine. Accordingly, in 83.3% of cases, these viruses were detected in the absence of the above-listed taxa of microorganisms in the urine. The normal urinary microbiota of healthy women and men has differences: Lactobacillus spp and Candida spp are absent in the urine of men while Streptococcus spp in urine of women. HHV6, HPV18, parvoviruses B19 are found in urine of healthy people and more often in men. Data about the virobiota and microbiota of urine in healthy people can highlight on the pathogenesis of urinary tract infections of various localization and develop targeted approaches in personalized therapy of this group of diseases.

Why are there proteins in the urine of healthy people?

<p indent=0mm>Proteins are essential nutrients for humans, but why is there a small amount of proteins excreted through urine? Although healthy people have low levels of protein in the urine, they are rich in variety. The proteins in them may be unnecessary wastes of the body or may even have a toxic effect on the body and must be excreted. Compared with small-molecule metabolites, proteins have a complex structure and various functions. Even a small change at the molecular level will affect their subsequent biological functions. A comprehensive comparison of the molecular level modifications of plasma and urine proteome, the difference may provide clues to the presence of protein in the urine. In this study, a total of 9 healthy people’s urine and 9 healthy people’s plasma samples were collected. The samples were analyzed by high-resolution tandem mass spectrometry and unlabeled quantitative proteomics techniques, and the non-limiting modification identification algorithm was used to to compare molecular modifications between two types of samples as a whole. The results showed that the amount of cysteine (Cys) modification to dehydroalanine (Dha) in the urine proteome was higher than that in plasma. The molecular modification [Cys→Dha] destroys the disulfide bond of the original protein, thereby affecting or even changing the structure and biological function of the protein. Therefore, this study revealed the differences in the overall proteome modification of plasma and urine and pointed out that the structure of protein may be irreversibly changed due to the difference in modification of protein molecules, which in turn caused proteins which lost their functions and even toxic proteins from the blood to be excreted into the urine.

Preconcentration of organic solutes in urine by bubble bursting

The chemical sensitivity of urine metabolomics analysis is greatly compromised due to the large amounts of inorganic salts in urine (NaCl, KCl), which are detrimental to analytical instrumentation, e.g. chromatographic columns or mass spectrometers. Traditional desalting approaches applied to urine pretreatment suffer from the chemical losses, which reduce the information depth of analysis. We aimed to test a simple approach for the simultaneous preconcentration and desalting of organic solutes in urine based on the collection of induced bursting bubble aerosols above the surface of urine samples. Bursting bubbles were generated at ambient conditions by feeding gas through an air diffuser at the bottom of diluted (200 times in ultrapure water) urine solution (50–500 mL). Collected aerosols were analyzed by the direct-infusion electrospray ionization mass spectrometry (ESI–MS). The simultaneous preconcentration (ca. 6–12 fold) and desalting (ca. six–tenfold) of organic solutes in urine was achieved by the bursting bubble sample pretreatment, which allowed ca. three-times higher number of identified urine metabolites by high-resolution MS analysis. No chemical losses due to bubbling were observed. The increased degree of MS data clustering was demonstrated on the principal component analysis of data sets from the urine of healthy people and from the urine people with renal insufficiency. At least ten times higher sensitivity of trace drug detection in urine was demonstrated for clenbuterol and salbutamol. Our results indicate the high versatility of bubble bursting as a simple pretreatment approach to enhance the chemical depth and sensitivity of urine analysis. The approach could be attractive for personalized medicine as well as for the diagnostics of renal disorders of different etiology (diabetic nephropathy, chronic renal failure, transplant-associated complications, oncological disorders). Urine desalting and preconcentration in bursting bubbles.

Human Urine Is Not Sterile - Shift of Paradigm

Objective: Until recently the generally accepted paradigm implied that urine of healthy people is sterile. In the present study, urine of healthy subjects was investigated by extended bacteriological methods. Material and Methods: Three midstream urine samples from 52 healthy subjects each (24 females, 28 males; 18-25 years of age) were investigated by an extended set of culture media for identification of facultative aerobic (FAB) and nonclostridial anaerobic bacteria (NCAB). Ward's method (Euclidean distance) was used for similarity analysis. Results: The bacterial count of FAB in urine was usually low (≤10² colony-forming units/ml) in both groups. In contrast, the bacterial count of NCAB was higher (≥10³ colony-forming units/ml), at least in some species, with significant differences between genders. The average number of bacterial species found was 5.8 in female and 7.1 in male urine. Half of the females were assigned to a specific ‘female' microbial spectrum, different from that of males. In the mixed-gender clusters, the males showed a greater similarity among themselves. Conclusions: As also shown by other investigators, urine of healthy people is normally not sterile. The role of the routinely not cultivated bacteria in healthy and diseased subjects needs to be established. It may alter the diagnostics of infectious and inflammatory diseases of the urogenital tract.

Novel Antibacterial Activity of Enterococcus faecium NM2 Isolated from Urine of Healthy People

Novel Antibacterial Activity of Enterococcus faecium NM2 Isolated from Urine of Healthy People

Формирование протеома мочи здорового человека

In the review it was represented the modern ideas on the processes involved in the formation of the protein composition of the urine of healthy people. In the last decade the development of highly sensitive mass spectrometric methods for the detection of proteins has given impetus to the study of the protein composition of human body fluids, including urine. Modern methods of separation of complex protein mixtures and determination of the individual components of these mixtures that are used in proteomics, can detect in urine significant number of proteins and peptides of different origin. Little-known, but very important problem for biomedical research is a physiological variation of the protein composition of urine revealed by proteomics. Under physiological conditions, there are many factors that affect the filtration of plasma proteins in the glomeruli and reabsorption in the proximal tubules of the nephron. These include hypoxia, oxidative stress, changes in acid-base balance and blood pressure, the effects of parathyroid hormone, angiotensin-II and other regulators of water and electrolyte metabolism. It is shown that the close structural and functional relationship of processes of reabsorption in the proximal tubules of the nephron causes dependence modulation of sodium reabsorption, water, chloride, phosphate, bicarbonate, and changes in the various parts of the process of re-absorption of the protein.

Surface properties of urine colloids of healthy people and patients with urolithiasis

Applying the microelectrophoresis and flow ultramicroscopy methods within a wide pH range at 10 -3 M NaCl, electrokinetic properties and aggregative stability of urine colloids of healthy people and patients with urolithiasis have been explored. Urine colloids of healthy people show the same dependence of the electrokinetic (z -) potential on the pH medium, but a high degree of heterogeneity in systems by their electrokinetic properties. As for urine colloids of patients with urolithiasis, they show various dependence of z – pH but less heterogeneity of electrokinetic properties in colloids of each urine sample. Coagulation kinetics of disperse systems obtained from the urine of healthy people, is qualitatively consistent with their electrophoretic properties. Suspended particles in the urine of healthy people generally show lower values of the Hamaker constant than those in the urine of patients with urolithiasis, which may evidence their higher affinity for water.

A computational method for prediction of excretory proteins and application to identification of gastric cancer markers in urine.

A novel computational method for prediction of proteins excreted into urine is presented. The method is based on the identification of a list of distinguishing features between proteins found in the urine of healthy people and proteins deemed not to be urine excretory. These features are used to train a classifier to distinguish the two classes of proteins. When used in conjunction with information of which proteins are differentially expressed in diseased tissues of a specific type versus control tissues, this method can be used to predict potential urine markers for the disease. Here we report the detailed algorithm of this method and an application to identification of urine markers for gastric cancer. The performance of the trained classifier on 163 proteins was experimentally validated using antibody arrays, achieving >80% true positive rate. By applying the classifier on differentially expressed genes in gastric cancer vs normal gastric tissues, it was found that endothelial lipase (EL) was substantially suppressed in the urine samples of 21 gastric cancer patients versus 21 healthy individuals. Overall, we have demonstrated that our predictor for urine excretory proteins is highly effective and could potentially serve as a powerful tool in searches for disease biomarkers in urine in general.

Rearranged JC Virus Noncoding Control Regions Found in Progressive Multifocal Leukoencephalopathy Patient Samples Increase Virus Early Gene Expression and Replication Rate

Polyomavirus JC (JCV) infects ∼ 60% of the general population, followed by asymptomatic urinary shedding in ∼ 20%. In patients with pronounced immunodeficiency, including HIV/AIDS, JCV can cause progressive multifocal leukoencephalopathy (PML), a devastating brain disease of high mortality. While JCV in the urine of healthy people has a linear noncoding control region called the archetype NCCR (at-NCCR), JCV in brain and cerebrospinal fluid (CSF) of PML patients bear rearranged NCCRs (rr-NCCRs). Although JCV NCCR rearrangements are deemed pathognomonic for PML, their role as a viral determinant is unclear. We sequenced JCV NCCRs found in CSF of eight HIV/AIDS patients newly diagnosed with PML and analyzed their effect on early and late gene expression using a bidirectional reporter vector recapitulating the circular polyomavirus early and late gene organization. The rr-NCCR sequences were highly diverse, but all increased viral early reporter gene expression in progenitor-derived astrocytes, glia-derived cells, and human kidney compared to the expression levels with the at-NCCR. The expression of simian virus 40 (SV40) large T antigen or HIV Tat expression in trans was associated with a strong increase of at-NCCR-controlled early gene expression, while rr-NCCRs were less responsive. The insertion of rr-NCCRs into the JCV genome backbone revealed higher viral replication rates for rr-NCCR compared to those of the at-NCCR JCV in human progenitor-derived astrocytes or glia cells, which was abrogated in SV40 large T-expressing COS-7 cells. We conclude that naturally occurring JCV rr-NCCR variants from PML patients confer increased early gene expression and higher replication rates compared to those of at-NCCR JCV and thereby increase cytopathology.

Isolation and Comparative Study of Cell‐Free Nucleic Acids from Human Urine

Cell-free nucleic acids (NA) from human urine were investigated. Concentrations of DNA and RNA in the urine of healthy people were independent of gender and were in the range of 6 ng/mL to 50 ng/mL and 24 ng/mL to 140 ng/mL, respectively. DNA fragments of 150-400 bp represent the main part of cell-free DNA, along with DNA fragments up to 1,300 bp, which were found in male urine, and DNA fragments up to 19 kbp, which were found in female urine. Analysis of circulating DNA, isolated from blood of breast cancer patients and cell-free DNA isolated from their urine by methylation-specific PCR, demonstrates that the presence of methylated promoters of RASSF1A and RARbeta2 genes in plasma was accompanied by the detection of the same methylated markers in urine. The data obtained demonstrate applicability of cell-free urine DNA in cancer diagnostics.

Human exposure to carcinogenic heterocyclic amines and their mutational fingerprints in experimental animals.

Heterocyclic amines (HCAs) are mutagens/carcinogens to which humans are exposed on almost a daily basis. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhlP) is the most abundant of the various carcinogenic HCAs (present at a level of 0.56 to 69.2 ng/g of cooked meat or fish), with 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx) following it at 0.64 to 6.44 ng/g. HCAs have been found in the urine of healthy people who consume ordinary diets, while patients receiving parenteral alimentation lack, for example, PhlP and MelQx in their urine. Based on the concentrations of PhlP and MelQx in urine samples from 10 healthy volunteers, daily intake of MelQx in Japanese was calculated to be 0.3 to 3.9 micrograms/person, while that of PhlP was 0.005 to 0 micrograms. The Japanese consume more MelQx than Americans, whereas Japanese intake of PhlP was about one-third that of Americans. MelQx-DNA adducts have also detected in Japanese Kidney, colon, and rectum samples using the 32P-postlabeling method followed by identification using high-performance liquid chromatography (HPLC) analysis; the levels were 0.18, 1.8, and 1.4 per 10(9) nucleotides, respectively. In addition, we elucidated the mutational fingerprints of Phlp by analyzing Apc mutations in rat colon cancers induced by this carcinogen. Four of eight tumors had a total of five mutations in the Apc gene, four of which featured a guanine deletion from 5'-GTGGGAT-3' sequences. This specific mutation spectrum may be used as a fingerprint of PhlP in evaluating its risk potential for human colon carcinogenesis. Mutations were not found in similar 2-amino-3-methylimidazo[4,5-f]quinoline-induced colon lesions. Microsatellite instability was detected in both colon and mammary tumors induced by PhlP. The mechanisms involved in this development of microsatellite instability in PhlP. The mechanisms involved in this development of microsatellite instability in PhlP-induced cancers remain to be elucidated.

Renal excretion of plasma soluble melanins by healthy human adults.

The soluble melanins of blood plasma form in vivo and in vitro from dopa, catecholamines, catechol, hydroquinone, homogentisic acid, 3-hydroxykynurenine, 3-hydroxyanthranilic acid, p-aminophenol, p-phenylenediamine and other structurally related end(ex)ogenous compounds by oxidative polymerization. The mean quantity of natural melanins in normal plasma is 1.61 +/- 0.10 (standard deviation) mg/ml, (n = 20) and in uraemic plasma 2.72 +/- 0.38 mg/ml, (n = 16). The plasma melanins (approximately 3%), are associated with proteins (approximately 85%), mucoproteins (approximately 0.25%), lipids (approximately 0.4%), as soluble lipofuscins, and probably are associated with proteins without lipids as soluble melanoproteins. Fluorescence, UV-VIS and IR spectroscopies and the melanin isolation method show the presence of soluble melanins in the urine of healthy people. Soluble melanins can also be formed in vitro in the urine by oxidative polymerization of the precursors. In most of the urine samples we studied, melanins were present in larger amounts than the urinary proteins, indicating that the kidneys can selectively excrete the melanin components of the lipofuscins, and that the solubility of melanins does not depend upon combination with proteins. The quantities of purified melanins precipitated with 6 N HCl at 110 degrees C during 72 h from urine samples collected during 24 h periods ranged from 0.1460 g to 3.7627 g (mean 1.1303 +/- 1.1739 g, n = 8) and the plasma clearance rates ranged from 0.06 ml/min to 1.56 ml/min (mean 0.48 +/- 0.48 ml/min, n = 8). From the individual 24 h urine samples we obtained from 9 to 216 mg/dl of precipitated melanins while the individual plasma samples contained from 145 to 175 mg/dl.