Low Citrate Levels Research Articles

Association between obesity and risk of kidney stones: exploring the rule of life style factors

Introduction: Kidney stones are a prevalent health concern, with obesity recognized as a significant risk factor. Understanding the interplay between obesity and lifestyle factors in stone formation is crucial. This study investigates this association, focusing on dietary habits, fluid intake, physical activity, and medication use. Methods: A one-year prospective April 2023–March 2024 saw the conduct of a cohort study at the Pakistan Academy of Medical Sciences (PIMS) in Pakistan's Islamabad. 88 participants were enrolled, with baseline data including demographics, BMI, medical history, and lifestyle factors. Follow-up assessments monitored weight changes, urinary parameters, and kidney stone incidence. Multivariate regression analysis explored associations between obesity, lifestyle factors, and stone risk. Results: Obese participants exhibited higher comorbidity prevalence and medication use. Over the study, obese participants gained 3.7 kg, while non-obese lost 1.5 kg. Obese individuals had elevated urinary calcium and oxalate, and lower citrate levels. Kidney stone incidence was 16.7% in obese and 9.5% in non-obese participants. Multivariate analysis identified obesity, high animal protein intake, and low fluid consumption as significant predictors of stone risk among obese individuals. Conclusion: This study underscores the complex relationship between obesity, lifestyle factors, and kidney stone risk. Modifiable factors like dietary habits and fluid intake play crucial roles in stone formation. Insights from this research can inform targeted interventions to reduce stone burden and improve health outcomes in obese individuals.

Early Systemic Glycolytic Shift After Aneurysmal Subarachnoid Hemorrhage is Associated with Functional Outcomes.

Aneurysmal subarachnoid hemorrhage (aSAH) leads to a robust systemic inflammatory response. We hypothesized that an early systemic glycolytic shift occurs after aSAH, resulting in a unique metabolic signature and affecting systemic inflammation. Control patients and patients with aSAH were analyzed. Samples from patients with aSAH were collected within 24h of aneurysmal rupture. Mass spectrometry-based metabolomics was performed to assess relative abundance of 16 metabolites involved in the tricarboxylic acid cycle, glycolysis, and pentose phosphate pathway. Principal component analysis was used to segregate control patients from patients with aSAH. Dendrograms were developed to depict correlations between metabolites and cytokines. Analytic models predicting functional outcomes were developed, and receiver operating curves were compared. A total of 122 patients with aSAH and 38 control patients were included. Patients with aSAH had higher levels of glycolytic metabolites (3-phosphoglycerate/2-phosphoglycerate, lactate) but lower levels of oxidative metabolites (succinate, malate, fumarate, and oxalate). Patients with higher clinical severity (Hunt-Hess Scale score ≥ 4) had higher levels of glyceraldehyde 3-phosphate and citrate but lower levels of α-ketoglutarate and glutamine. Principal component analysis readily segregated control patients from patients with aSAH. Correlation analysis revealed distinct clusters in control patients that were not observed in patients with aSAH. Higher levels of fumarate were associated with good functional outcomes at discharge (odds ratio [OR] 1.76, 95% confidence interval [CI] 1.15-2.82) in multivariablemodels, whereas higher levels of citrate were associated with poor functional outcomes at discharge (OR 0.36, 95% CI 0.16-0.73) and at 3months (OR 0.35, 95% CI 0.14-0.81). No associations were found with delayed cerebral ischemia. Levels of α-ketoglutarate and glutamine correlated with lower levels of interleukin-8, whereas fumarate was associated with lower levels of tumor necrosis factor alpha. Aneurysmal subarachnoid hemorrhage results in a unique pattern of plasma metabolites, indicating a shift toward glycolysis. Higher levels of fumarate and lower levels of citrate were associated with better functional outcomes. These metabolites may represent targets to improve metabolism after aSAH.

Novel Serum and Urinary Metabolites Associated with Diabetic Retinopathy in Three Asian Cohorts.

Diabetic retinopathy (DR) is a microvascular complication of diabetes mellitus, a metabolic disorder, but understanding of its pathophysiology remains incomplete. Meta-analysis of three population-based cross-sectional studies (2004–11) representing three major Asian ethnic groups (aged 40–80 years: Chinese, 592; Malays, 1052; Indians, 1320) was performed. A panel of 228 serum/plasma metabolites and 54 urinary metabolites were quantified using nuclear magnetic resonance (NMR) spectroscopy. Main outcomes were defined as any DR, moderate/above DR, and vision-threatening DR assessed from retinal photographs. The relationship between metabolites and DR outcomes was assessed using multivariate logistic regression models, and metabolites significant after Bonferroni correction were meta-analyzed. Among serum/plasma metabolites, lower levels of tyrosine and cholesterol esters to total lipids ratio in IDL and higher levels of creatinine were positively associated with all three outcomes of DR (all p < 0.005). Among urinary metabolites, lower levels of citrate, ethanolamine, formate, and hypoxanthine were positively associated with all three DR outcomes (all p < 0.005). Higher levels of serum/plasma 3-hydroxybutyrate and lower levels of urinary 3-hydroxyisobutyrate were associated with VTDR. Comprehensive metabolic profiling in three large Asian cohorts with DR demonstrated alterations in serum/plasma and urinary metabolites mostly related to amino acids, lipoprotein subclasses, kidney function, and glycolysis.

P0035URINARY CITRATE AS A MARKER OF RENAL FUNCTION IN PATIENTS WITH AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Abstract Background and Aims In autosomal dominant polycystic kidney disease (ADPKD) is frequent to find low urinary citrate levels. Recently it has been suggested that urinary citrate could be a marker of covert metabolic acidosis. Our aim was to analyze relationship between urinary citrate levels and renal functionality in ADPKD patients. Method We determined citrate, calcium and uric acid in 24-hour collected urine from 91 ADPKD patients Results Urinary citrate/creatinine ratio was 214±158 (range 5.3-678) mg/g Cr with levels significantly higher in females. When considering chronic kidney disease (CKD) stages we observed a progressive decrease in urinary osmolality and in urinary citrate, calcium and uric acid elimination. Low levels of citrate (&amp;lt;300 mg/g Cr) were present in 40% in CKD-1 stage, in 69.7% in CKD-2 stage, 92% in CKD-3 stage and 100% in CKD-4 + 5 stages. Urinary citrate was correlated with serum creatinine (r= -0.66, p&amp;lt;0.001) and eGFR (r= 0.56, p&amp;lt;0.001). Urinary citrate significantly correlated with urinary calcium but correlation with urinary uric acid was weaker. We did not find any correlation with serum bicarbonate. Using multiple lineal regression analysis we found as predictors of urinary citrate to glomerular filtration rate, female gender and urinary calcium levels. In a subgroup of patients we measured total kidney volume and we found an inverse correlation with urinary citrate levels that dissappeared when it was corrected with glomerular filtration rate. We did not also find a relationship between urinary elimination of calcium or uric acid and TKV after adjusting with eGFR. Conclusion Urinary citrate is very frequently reduced in ADPKD patients being present from very early CKD stages. Their levels are inversely correlated with glomerular filtration rate and directly with urinary calcium excretion. We did not found a relathionship with serum bicarbonate. We think that it would be interesting to study urinary citrate in other nephropathies and verify if it could be a marker of covert metabolic acidosis.

Influence of BMI in nephrolithiasis in an Appalachian pediatric population: A single-center experience

The prevalence of pediatric nephrolithiasis has increased significantly in the past 20 years. Metabolic abnormalities predisposing adults to nephrolithiasis in obese patients include increased urinary sodium and uric acid excretion as well as low urine pH; however, limited data are available in the pediatric population. The aim was to investigate whether obese pediatric patients presenting with nephrolithiasis have a unique metabolic profile similar to reported findings in obese adults with nephrolithiasis. A retrospective chart review was performed in children aged 1-18 years seen at Kentucky Children's Hospital between 2010 and 2016. Inclusion criteria included all patients with documented stones confirmed by ultrasonography or computed tomography. A total of 111 patient charts were reviewed in the study with a mean age of 11.8±4.2 years. Seventy patients (63%) had a normal BMI and 41 patients (37%) were considered overweight/obese. There was no statistically significant relationship between BMI and stone recurrence. Obese patients had significantly decreased levels of urinary citrate, oxalate, magnesium, and potassium with significant elevations of urinary urea nitrogen, ammonia, and low urine pH compared with normal weight patients (Summary Figure). Several groups have reported on metabolic findings within obese and non-obese pediatric patients. A Turkish study reported increased oxalate excretion and hypocitraturia in obese patients while a Korean study also reported increased rates of hypocitraturia in recurrent stone formers. Similar to these studies, we did find significant differences in citrate within our study population; however, we found significantly lower levels of urinary oxalate in obese patients. The majority of these studies do not report an association with BMI and urine pH although this has been reported in the adult population and our findings support an inverse relationship between body mass index (BMI) and pH. Our group found a higher level of calcium phosphate stones, supporting of Eisner's findings that high BMI is associated with increased supersaturation of calcium phosphate. Limitations of our study include being a single center and retrospective in nature. Our study demonstrates differences in types of stones and urinary metabolites in an obese pediatric population suggestive of different metabolic profiles contributing to stone disease. We report similar association between BMI and urine pH, urinary potassium, and citrate. This study confirmed our primary hypothesis that obese pediatric patients would have a different urinary mineral profile as evidenced by lower levels of citrate and potassium and low urine pH; however, obese patients did not exhibit significantly elevated urinary sodium and uric acid when normalized to weight, as described in the adult population. Our study did not confirm our secondary hypothesis that stone composition would be associated with BMI status or stone recurrence.

Assessing Exposome Effects on Pregnancy through Urine Metabolomics of a Portuguese (Estarreja) Cohort.

This nuclear magnetic resonance metabolomics study compared the influence of two different central Portugal exposomes, one of which comprised an important source of pollutants (the Estarreja Chemical Complex, ECC), on the urinary metabolic trajectory of a cohort of healthy pregnant women (total n = 107). An exposome-independent description of pregnancy metabolism was found to comprise a set of 18 metabolites reflecting expected changes in branched-chain amino acid catabolism and hormone and lipid metabolisms. In addition, a set of small changes in some metabolites was suggested to be exposome-dependent and characteristic of pregnant subjects from the Estarreja region. These results suggested that the Estarreja exposome may impact to a very low extent pregnancy metabolism, inducing slight changes in amino acid metabolism (alanine, glycine, and 3-hydroxyisobutyrate, possibly involved in valine metabolism), tricarboxylic acid (TCA) cycle (cis-aconitate), diet, or gut microflora (furoylglycine) as well as allantoin, 2-hydroxyisobutyrate, and an unassigned resonance at δ 8.45. Furthermore, the urine of Estarreja subjects was found to generally contain higher levels of 4-hydroxyphenylacetate and lower levels of citrate. However, out of the above metabolites, only glycine and citrate seemed to correlate with the proximity to the ECC, with slightly relative higher levels of these compounds found for subjects living closer to the ECC. This suggested possible small effects of local pollutants on energy metabolism, with the remaining exposome-dependent metabolite changes most probably originating from other aspects of the local exposome such as diet and lifestyle. Despite the limitation of this study regarding the unavailability of objective environmental parameters for the period under study, our results confirm the usefulness of metabolomics of human urine to gauge exposome effects on human health and, particularly, during pregnancy.

Reference intervals for stone risk factors in 24-h urine among healthy adults of the Han population in China.

The aim of the study was to establish reference intervals for 24-h urinary stone risk factors in the healthy Chinese Han population. From May 2013 to July 2014, we collected and analyzed 24-h urine samples from healthy adult Han population during a cross-sectional study across China. The protocol for analysis of 24-h urine included volume, pH, oxalate, citrate, sodium, potassium, chloride, calcium, phosphorous, creatinine, urate, magnesium, the ion activity products of calcium oxalate (AP(CaOx) indexs) and calcium phosphate (AP(CaP) indexs). We calculated the reference intervals according to the Clinical and Laboratory Standards Institute (CLSI) 2008 guidelines and compared them with those recorded in other studies. A total of 132 male and 123 female healthy subjects with a mean (SD, range) age of 52.4 (15.2, 19-89) years were eligible in the final analysis. Men had higher 24-h excretion of creatinine, calcium, urate and phosphorus and lower levels of citrate, magnesium, chloride, sodium and potassium than women. AP(CaOx) indexs and AP(CaP) indexs were significantly higher among men than women. When urinary findings were compared with the reference intervals, most of our data showed a high abnormality rate, especially for creatinine, calcium, citrate, magnesium, chloride, sodium and potassium. The present study revealed the normal metabolic status for stone risk factors of the Chinese Han population. It is therefore necessary for each country or region to define their own reference intervals for comparison of stone risk factors between patients and healthy subjects.

Metabolomic analysis of urine with Nuclear Magnetic Resonance spectroscopy in patients with idiopathic sudden sensorineural hearing loss: A preliminary study

ObjectiveIdiopathic sudden sensorineural hearing loss is a frequent emergency, with unknown aetiology and usually treated with empiric therapy. Steroids represent the only validated treatment but prognosis is unpredictable and the possibility to select the patients who will not respond to steroids could avoid unnecessary treatments. Metabolomic profiling of the biofluids target the analysis of the final product of genic expression and enzymatic activity, defining the biochemical phenotype of a whole biologic system. MethodsWe studied the metabolomics of the urine of a cohort of patients with idiopathic sudden sensorineural hearing loss, correlating the metabolic profiles with the clinical outcomes. Metabolomic profiling of urine samples was performed by 1H Nuclear Magnetic Resonance spectroscopy in combination with multivariate statistical approaches. Results26 patients were included in the study: 5 healthy controls, 13 patients who did not recover after treatment at 6 months while the remaining 8 patients recovered from the hearing loss. The orthogonal partial least square-discriminant analysis score plot showed a significant separation between the two groups, responders and non-responders after steroid therapy, R2Y of 0.83, Q2 of 0.38 and p value <0.05. The resulting metabolic profiles were characterized by higher levels of urinary B-Alanine, 3-hydroxybutyrate and Trimethylamine N-oxide, and lower levels of Citrate and Creatinine in patients with worst outcome. ConclusionIdiopathic sudden sensorineural hearing loss is a specific disease with unclear systemic changes, but our data suggest that there are different types of this disorder or patients predisposed to effective action of steroids allowing the recover after treatment.

Bioweathering Potential of Cultivable Fungi Associated with Semi-Arid Surface Microhabitats of Mayan Buildings.

Soil and rock surfaces support microbial communities involved in mineral weathering processes. Using selective isolation, fungi were obtained from limestone surfaces of Mayan monuments in the semi-arid climate at Yucatan, Mexico. A total of 101 isolates representing 53 different taxa were studied. Common fungi such as Fusarium, Pestalotiopsis, Trichoderma, and Penicillium were associated with surfaces and were, probably derived from airborne spores. In contrast, unusual fungi such as Rosellinia, Annulohypoxylon, and Xylaria were predominantly identified from mycelium particles of biofilm biomass. Simulating oligotrophic conditions, agar amended with CaCO3 was inoculated with fungi to test for carbonate activity. A substantial proportion of fungi, in particular those isolated from mycelium (59%), were capable of solubilizing calcium by means of organic acid release, notably oxalic acid as evidenced by ion chromatography. Contrary to our hypothesis, nutrient level was not a variable influencing the CaCO3 solubilization ability among isolates. Particularly active fungi (Annulohypoxylon stygium, Penicillium oxalicum, and Rosellinia sp.) were selected as models for bioweathering experiments with limestone-containing mesocosms to identify if other mineral phases, in addition to oxalates, were linked to bioweathering processes. Fungal biofilms were seen heavily covering the stone surface, while a biomineralized front was also observed at the stone-biofilm interface, where network of hyphae and mycogenic crystals was observed. X-ray diffraction analysis (XRD) identified calcite as the main phase, along with whewellite and wedellite. In addition, lower levels of citrate were detected by Attenuated Total Reflectance-Fourier-Transform Infrared Spectroscopy (ATR-FTIR). Overall, our results suggest that a diverse fungal community is associated with limestone surfaces insemi-arid climates. A subset of this community is geochemically active, excreting organic acids under quasi-oligotrophic conditions, suggesting that the high metabolic cost of exuding organic acids beneficial under nutrient limitation. Oxalic acid release may deteriorate or stabilize limestone surfaces, depending on microclimatic dynamics.

Does Hypertension Impact 24-Hour Urine Parameters in Patients With Nephrolithiasis?

To examine the differences in 24-hour urine parameters and stone composition between patients with and without systemic hypertension (HTN) in a large cohort of stone formers. We performed a retrospective review over a 10-year period of patients with stone, who had completed a 24-hour urinalysis (Litholink) and for whom demographic information was available, including the presence of HTN. Univariate and multivariate analyses were performed, comparing the 24-hour urinalysis profiles of patients with HTN with that of normotensive patients. Of the 1115 patients eligible for inclusion, 442 patients (40%) had HTN and 673 (60%) did not. Patients with HTN were significantly older, had a higher body mass index, and had a greater number of comorbid conditions than normotensive patients. Univariate analysis revealed significantly lower urine pH, calcium, supersaturation (SS) of calcium oxalate (CaOx) and SS calcium phosphate (all P<.05) in patients with HTN. Multivariate analysis showed significantly lower calcium, citrate, and SS CaOx in patients with HTN (all P<.05). Our results demonstrate lower levels of calcium and SS CaOx on univariate and multivariate analysis, as well as lower levels of citrate on multivariate analysis in patients with HTN. These results suggest that lower levels of citrate may contribute to stone formation to a greater degree in patients with HTN than abnormalities in calcium metabolism.

Nuclear magnetic resonance metabolomics of iron deficiency in soybean leaves.

Iron (Fe) deficiency is an important agricultural concern that leads to lower yields and crop quality. A better understanding of the condition at the metabolome level could contribute to the design of strategies to ameliorate Fe-deficiency problems. Fe-sufficient and Fe-deficient soybean leaf extracts and whole leaves were analyzed by liquid (1)H nuclear magnetic resonance (NMR) and high-resolution magic-angle spinning NMR spectroscopy, respectively. Overall, 30 compounds were measurable and identifiable (comprising amino and organic acids, fatty acids, carbohydrates, alcohols, polyphenols, and others), along with 22 additional spin systems (still unassigned). Thus, metabolite differences between treatment conditions could be evaluated for different compound families simultaneously. Statistically relevant metabolite changes upon Fe deficiency included higher levels of alanine, asparagine/aspartate, threonine, valine, GABA, acetate, choline, ethanolamine, hypoxanthine, trigonelline, and polyphenols and lower levels of citrate, malate, ethanol, methanol, chlorogenate, and 3-methyl-2-oxovalerate. The data indicate that the main metabolic impacts of Fe deficiency in soybean include enhanced tricarboxylic acid cycle activity, enhanced activation of oxidative stress protection mechanisms and enhanced amino acid accumulation. Metabolites showing accumulation differences in Fe-starved but visually asymptomatic leaves could serve as biomarkers for early detection of Fe-deficiency stress.

Dual role of CcpC protein in regulation of aconitase gene expression in Listeria monocytogenes and Bacillus subtilis

The role of the CcpC regulatory protein as a repressor of the genes encoding the tricarboxylic acid branch enzymes of the Krebs cycle (citrate synthase, citZ; aconitase, citB; and isocitrate dehydrogenase, citC) has been established for both Bacillus subtilis and Listeria monocytogenes. In addition, hyperexpression of citB-lacZ reporter constructs in an aconitase null mutant strain has been reported for B. subtilis. We show here that such hyperexpression of citB occurs in L. monocytogenes as well as in B. subtilis and that in both species the hyperexpression is unexpectedly dependent on CcpC. We propose a revision of the existing CcpC-citB regulatory scheme and suggest a mechanism of regulation in which CcpC represses citB expression at low citrate levels and activates citB expression when citrate levels are high.

833 IS BMI ASSOCIATED WITH STONE FORMATION IN CHILDREN? SINGLE CENTER, PROSPECTIVE ANALYSIS

INTRODUCTION AND OBJECTIVES: Multiple reports exist identifying an increasing epidemic of pediatric urolithiasis in the modern era. Causative factors have been postulated, such as the obesity and fast food epidemics. We hypothesize that BMI is not truly causative, but more likely a confounding factor, in pediatric stone formers. METHODS: A two-year prospective clinical trial enrolled 52 patients through the Pediatric Urology department at the Childreni s Hospital of Pittsburgh. Patient demographics, BMI, method of stone diagnosis, stone analysis, 24 hour urine studies, labs and spot urine studies, and treatments were catalogued. Logistic regression analysis was used to compare variables among stone forming children iU age 18. RESULTS: Data on BMI was available for 49 of 52 stone forming children. Imaging data was available in 46 of 49 patients, including confirmation by CT in 40 (87%), ultrasound in 3 (6.5%), and KUB in 3 (6.5%). The median age of presenting children was 15 (mean: 14.4 2.5), median stone burden 2.8mm (mean: 3.5 1.7) and median BMI 20.0 (mean: 20.4 4.2). Approximately 10% (5/49) children were overweight (BMI 25-30) and only 2% (1/49) were obese. Infected stones were present in 2 children (4.3%), and end stage renal failure in 1 (2.2%). Litholink® studies were completed on all 49 patients; 24hr urine electrolytes are as outlined in Table 1. No patients had cystinuria. CONCLUSIONS: mong pediatric stone formers, we did not find higher rates of obesity than compared with the local population. In fact, all overweight children forming stones in our cohort accounted for only 10% of total patients. Both normal and overweight children had low citrate levels by Litholink assay, although overweight children had a more substantial reduction in urinary citrate. Greater patient numbers are needed to determine the true effect of obesity on 24 hour urine parameters, and the reversible causes for increased stone formation, including dietary analysis.

Nickel Deficiency Disrupts Metabolism of Ureides, Amino Acids, and Organic Acids of Young Pecan Foliage

The existence of nickel (Ni) deficiency is becoming increasingly apparent in crops, especially for ureide-transporting woody perennials, but its physiological role is poorly understood. We evaluated the concentrations of ureides, amino acids, and organic acids in photosynthetic foliar tissue from Ni-sufficient (Ni-S) versus Ni-deficient (Ni-D) pecan (Carya illinoinensis [Wangenh.] K. Koch). Foliage of Ni-D pecan seedlings exhibited metabolic disruption of nitrogen metabolism via ureide catabolism, amino acid metabolism, and ornithine cycle intermediates. Disruption of ureide catabolism in Ni-D foliage resulted in accumulation of xanthine, allantoic acid, ureidoglycolate, and citrulline, but total ureides, urea concentration, and urease activity were reduced. Disruption of amino acid metabolism in Ni-D foliage resulted in accumulation of glycine, valine, isoleucine, tyrosine, tryptophan, arginine, and total free amino acids, and lower concentrations of histidine and glutamic acid. Ni deficiency also disrupted the citric acid cycle, the second stage of respiration, where Ni-D foliage contained very low levels of citrate compared to Ni-S foliage. Disruption of carbon metabolism was also via accumulation of lactic and oxalic acids. The results indicate that mouse-ear, a key morphological symptom, is likely linked to the toxic accumulation of oxalic and lactic acids in the rapidly growing tips and margins of leaflets. Our results support the role of Ni as an essential plant nutrient element. The magnitude of metabolic disruption exhibited in Ni-D pecan is evidence of the existence of unidentified physiological roles for Ni in pecan.

Differential aluminum tolerance in soybean: An evaluation of the role of organic acids.

The role of organic acids in aluminum (Al) tolerance has been the object of intensive research. In the present work, we evaluated the roles of organic acid exudation and concentrations at the root tip on Al tolerance of soybean. Exposing soybean seedlings to Al3+ activities up to 4.7 &mgr;M in solution led to different degrees of restriction of primary root elongation. Al tolerance among genotypes was associated with citrate accumulation and excretion into the external media. Citrate and malate efflux increased in all genotypes during the first 6 h of Al exposure, but only citrate efflux in Al-tolerant genotypes was sustained for an extended period. Tolerance to Al was correlated with the concentration of citrate in root tips of 8 genotypes with a range of Al sensitivities (r2=0.75). The fluorescent stain lumogallion indicated that more Al accumulated in root tips of the Al-sensitive genotype Young than the Al-tolerant genotype PI 416937, suggesting that the sustained release of citrate from roots of the tolerant genotype was involved in Al exclusion. The initial stimulation of citrate and malate excretion and accumulation in the tip of all genotypes suggested the involvement of additional tolerance mechanisms. The experiments included an examination of Al effects on lateral root elongation. Extension of lateral roots was more sensitive to Al than that of tap roots, and lateral root tips accumulated more Al and had lower levels of citrate.

Single-voxel oversampled J-resolved spectroscopy of in vivo human prostate tissue.

Single-voxel J-resolved spectroscopy with oversampling in the F1 dimension was used to obtain water unsuppressed 1H spectra of in situ human prostate tissue in 40 previously untreated prostate cancer patients. Based on T2-weighted MRI and previous biopsy information, voxels were placed in regions of benign or malignant peripheral zone tissue, or in regions of predominantly glandular or stromal benign prostatic hyperplasia (BPH) within the central gland. The addition of a second J-resolved dimension allowed for the observation of the J-modulation of citrate, as well as the resolution of polyamines from overlapping choline and creatine signals. Regions of healthy peripheral zone tissue and glandular BPH all demonstrated high levels of citrate and polyamines, with consistent coupling and J-modulation patterns. Conversely, regions of malignant peripheral zone tissue and stromal BPH demonstrated low levels of citrate and polyamines consistent with prior in vivo and ex vivo studies. Moreover, water T2 relaxation times determined for healthy peripheral zone tissue (mean 128 +/- 15.2 msec) were significantly different than for malignant peripheral zone tissue (mean 88.0 +/- 14.2 msec, P = 0.005), as well as for predominantly glandular (mean 92.4 +/- 12.2 msec, P = 0.009) and stromal BPH (mean 70.9 +/- 12.1 msec, P = 0.003). This preliminary study demonstrates that J-resolved spectroscopy of the in situ prostate can be acquired, and the information obtained from the second spectral dimension can provide additional physiologic information from human prostate tissue in a reasonable amount of time (< 10 min).

In vitro high resolution 1H-spectroscopy of the human prostate: benign prostatic hyperplasia, normal peripheral zone and adenocarcinoma.

1H-spectra at 360 MHz from perchloric extracts of 35 human prostate specimens were obtained. First, we sought to define what peaks can be assigned in vitro, and thus, potentially seen in vivo. Second, we sought to try to discriminate between adenocarcinoma, normal peripheral zone and benign prostatic hyperplasia using spectral fingerprints. Thirteen samples of adenocarcinoma, 11 samples of benign prostatic hyperplasia, and 11 samples of normal contralateral peripheral zone were analyzed by obtaining a ratio from the maximum area of each major peak and the area of an added standard (3-trimethyl-silyl-propionic acid). There was a significantly larger benign prostate hyperplasia citrate standardized peak area when compared to the adenocarcinoma citrate standardized peak area for each patient (P < 0.05). However, the citrate standardized peak areas from the normal peripheral zones were not significantly different from those found in the adenocarcinomas. Four out of 13 cases of stromal hyperplasia had similarly low levels of citrate as their respective gland's adenocarcinoma. We also found a sharp peak at 2.05 ppm that was seen in 4 out of 13 adenocarcinoma samples and in only 1 out of 13 of the benign prostate hypertrophy samples which has tentatively been assigned to N-acetyl neuraminic acid. Further studies are required to assess whether low citrate levels alone can serve to exclusively diagnose adenocarcinoma of the prostate.

Citrate alterations in primary and metastatic human prostatic adenocarcinomas: 1H magnetic resonance spectroscopy and biochemical study.

The objectives of this study were to quantitatively verify the low levels of citrate previously observed in primary human prostatic adenocarcinomas and to determine whether citrate was further reduced in metastatic prostatic cancer. This was accomplished by comparison of citrate concentrations of DU 145 xenografts (a poorly differentiated human prostatic adenocarcinoma cell line grown in nude mice) with concentrations in primary human adenocarcinomas. Following in vivo 1H NMR studies of DU 145 xenografts, citrate concentrations of DU 145 xenografts and surgically removed primary prostatic adenocarcinoma tissue were determined by quantitative high resolution 1H NMR and enzymatic assay. The most significant findings of this study were that citrate concentrations in primary human adenocarcinomas (3.74 +/- 0.19 mumol/g wet weight) were significantly lower than those observed for normal and benign hyperplastic (BPH) prostatic tissues. Furthermore there was a further ten-fold reduction of citrate associated with DU 145 xenografts (0.31 +/- 0.028 mumole/g wet weight) compared with primary prostatic cancer. DU 145 xenografts also exhibited higher levels of uridine diphosphosugars and choline containing metabolites relative to primary prostatic adenocarcinomas. These findings support the hypothesis that citrate is low in primary prostatic cancer and further reduced in metastatic disease.

The Effect of Different Concentrations of Citrate in Drinks on Plaque pH

The effect of 0.1, 0.2 and 0.4% citrate in 10% sucrose solutions on the plaque pH in vivo was tested in 20 volunteers using the plaque harvesting technique. Results showed that the pH response for the three test solutions with citrate was significantly less compared with that for 10% sucrose (positive control) alone (p < 0.05). Mean areas under the pH curve were: sorbitol (negative control) 0.02, citrate 0.2% 5.30, citrate 0.4% 6.24, citrate 0.1% 6.94 and 10% 12.69. The cariogenic potential index of all the citrate test drinks was almost half compared with a 10% sucrose solution (p < 0.05). It was concluded that the addition of relatively low levels of citrate in a sucrose solution reduces the acidogenic response in the plaque.

Biochemical activities during lipid accumulation in Candida curvata.

Intracellular and extracellular concentrations of citrate and the specific activities of ten different enzymes in Candida curvata D were examined in relation to lipid biosynthesis in batch and continuous culture. Citrate was found to accumulate prior to lipid production and declined markedly as lipid accumulated in batch culture. The cells excreted citrate as the culture became nitrogen-limiting after 30 hr of growth, but little more was expelled after 40 hr when lipid accumulation was more marked. In continuous culture, only low levels of citrate were detected at the lower dilution rates and citrate was completely absent from both the cells and medium above a dilution rate of 0.1/hr. The activity of malic enzyme, malate dehydrogenase and ATP:citrate lyase increased in batch culture on lipid accumulated and, in continuous culture, both malic enzyme and ATP:citrate lyase varied in parallel with the specific rate of lipid synthesis which increased with increasing dilution rate. Activity of malate dehydrogenase, citrate synthase and glucose-6-phosphate dehydrogenase decreased with increasing dilution rate. The regulatory significance of these enzymes in lipid accumulation by C. curvata is discussed.