Urinary oxalic acid excretion differs after oral loading of rats with various oxalate salts

BACKGROUND: To compare urinary oxalate excretion after the oral administration of oxalic acid, disodium oxalate, or calcium oxalate in rats. METHODS: Male Wistar rats were divided into four groups of six rats each and were intravenously hydrated with normal saline, and then were administered normal saline (control group), 10 mg of oxalic acid, equimolar disodium oxalate, or equimolar calcium oxalate via a gastrostomy. Urine specimens were collected just before administration and at hourly intervals up to 5 h afterwards. The urinary oxalate, calcium, magnesium and phosphorus levels were measured. RESULTS: Urinary oxalate excretion peaked at 1-2 h after administration of oxalic acid or equimolar disodium oxalate, while administration of calcium oxalate only caused a small increase of urinary oxalate excretion. Cumulative urinary oxalate excretion during 5 h was 1.69 +/- 0.10 mg (mean +/- SD; 17%), 1.43 +/- 0.13 mg (13%), and 0.22 +/- 0.03 mg (2%) after the administration of oxalic acid, disodium oxalate, and calcium oxalate, respectively. Urinary calcium excretion showed a decrease in the oxalic acid and disodium oxalate groups, while urinary magnesium or phosphorus excretion did not change significantly. CONCLUSION: The upper gastrointestinal tract seems to be the major site of oxalic acid absorption and only free oxalate is absorbed irrespective of whether it is the sodium salt or not. After binding to calcium in the gut, oxalic acid absorption seems to be inhibited in the presence of calcium and this means that calcium oxalate is poorly absorbed (at least in the upper gastrointestinal tract).     

Peak bone strength is influenced by calcium intake in growing rats

In this study we investigated the effect of supplementing the diet of the growing male rat with different levels of calcium (from low to higher than recommended intakes at constant Ca/P ratio), on multiple factors (bone mass, strength, size, geometry, material properties, turnover) influencing bone strength during the bone accrual period. Rats, age 28 days were supplemented for 4 weeks with high Ca (1.2%), adequate Ca (0.5%) or low Ca level (0.2%). Bone metabolism and structural parameters were measured. No changes in body weight or food intake were observed among the groups. As anticipated, compared to the adequate Ca intake, low-Ca intake had a detrimental impact on bone growth (33.63 vs. 33.68 mm), bone strength (− 19.7% for failure load), bone architecture (− 58% for BV/TV) and peak bone mass accrual (− 29% for BMD) due to the hormonal disruption implied in Ca metabolism. In contrast, novel, surprising results were observed in that higher than adequate Ca intake resulted in improved peak bone strength (106 vs. 184 N/mm for the stiffness and 61 vs. 89 N for the failure load) and bone material properties (467 vs. 514 mPa for tissue hardness) but these effects were not accompanied by changes in bone mass, size, microarchitecture or bone turnover. Hormonal factors, IGF-I and bone modeling were also evaluated. Compared to the adequate level of Ca, IGF-I level was significantly lower in the low-Ca intake group and significantly higher in the high-Ca intake group. No detrimental effects of high Ca were observed on bone modeling (assessed by histomorphometry and bone markers), at least in this short-term intervention. In conclusion, the decrease in failure load in the low calcium group can be explained by the change in bone geometry and bone mass parameters. Thus, improvements in mechanical properties can be explained by the improved quality of intrinsic bone tissue as shown by nanoindentation. These results suggest that supplemental Ca may be beneficial for the attainment of peak bone strength and that multiple factors linked to bone mass and strength should be taken into account when setting dietary levels of adequate mineral intake to support optimal peak bone mass acquisition.     

Urinary cAMP and calcium excretion in the fasting state and their response to oral calcium loading in patients with calcium urolithiasis

Fifty-two patients with idiopathic calcareous urolithiasis (ICU) were studied with an oral calcium loading test. Twenty-one subjects were normo-calciuric with no other detectable abnormalities (NDA). Of 31 patients with hypercalciuria, 16 had elevated fasting urinary calcium excretion (UCaE) (HFC), and 15 had normal UCaE (NFC). The fasting UCaE was significantly higher and the theoretical renal threshold for phosphate (TmPO4) was significantly lower in ICU patients as compared to 19 control individuals. The mean post oral calcium loading (Post Ca) UCaE rose significantly in hypercalciuric patients compared with control subjects; however, only 18/31 (58 per cent) had values above the normal range. There was no correlation between the fasting UCaE and either the immunoreactive parathyroid hormone (iPTH) or nephrogenous cAMP (ncAMP) in ICU patients. The fasting ncAMP was normal in all subjects with ICU and 7 of 52 subjects had elevated fasting iPTH values. When ranked according to the fasting UCaE value, ICU patients formed a continuum in which the NDA and HFC groups represented the extremes. It is concluded that the responses to oral Ca loading serve no useful role in the identification of an individual ICU patient either in terms of the pathogenetic subgroup or in the differentiation from normal controls.     

The urinary response to an oral oxalate load in recurrent calcium stone formers

PURPOSE: Dietary oxalate may contribute up to 50% to 80% of the oxalate excreted in urine. We studied the urinary response to an oral oxalate load in male and female idiopathic recurrent calcium oxalate stone formers with and without mild hyperoxaluria to evaluate the potential pathophysiological significance of dietary oxalate. MATERIALS AND METHODS: A total of 60 recurrent calcium stone formers underwent an oral oxalate load test. Urine samples were obtained after an overnight fast. Each patient then received an oral oxalate load (5 mM. sodium oxalate dissolved in 250 ml. distilled water) and 3, 2-hour urine samples were obtained 2, 4 and 6 hours after the oxalate load. We compared the response to the oxalate load in patients with and without mild hyperoxaluria, and in male and female patients without hyperoxaluria. RESULTS: The peak urinary response occurred 4 hours after the oral oxalate load in all patients. Those with mild hyperoxaluria had a mean fasting urinary oxalate-to-creatinine ratio +/- SE of 0.027 +/- 0.003 and a mean peak urinary oxalate-to-creatinine ratio of 0.071 +/- 0.006. In comparison, patients with normal oxalate excretion had a fasting and peak urinary oxalate-to-creatinine ratio of 0.018 +/- 0.001 and 0.056 +/- 0.004, respectively (p <0.05). The mean 6-hour increment for urinary oxalate excretion after the oxalate load for patients with hyperoxaluria versus those with normal urinary oxalate excretion was 17.2 +/- 1.9 versus 12.1 +/- 0.98 mg. (p <0.05). In the subset of patients with normal urinary oxalate excretion mean 6-hour cumulative urinary oxalate excretion was 16.8 +/- 1.3 and 13.3 +/- 1.4 mg. in males and females, respectively (p not significant). CONCLUSIONS: Recurrent calcium stone formers with mild hyperoxaluria have higher fasting urinary oxalate and an exaggerated urinary response to an oral oxalate load compared with recurrent calcium stone formers with normal urinary oxalate excretion. Men and women stone formers without hyperoxaluria excrete similar fractions of an oral oxalate load. Increased gastrointestinal absorption and renal excretion of dietary oxalate may be a significant pathophysiological mechanism of stone formation in patients with mild hyperoxaluria.     

Urinary excretion of orally administered oxalic acid in saccharin and o-phenylphenol-fed NMRI mice

Both saccharin and o-phenylphenol have been suggested to be carcinogenic to the urinary bladder in experimental animals, but the mechanism has remained unclear. The aim of this study was to investigate the effects of dietary saccharin and o-phenylphenol on the urinary excretion of dietary oxalic acid. Male NMRI mice were gradually adapted to either 3% o-phenylphenol or 5% saccharin in their diet. Having being adapted to these diets for 1 week or after consuming them for 3 months, the animals were fasted for 6 h and given a 2.5-microCi oral dose of U-14C-oxalic acid. Dosed animals were kept in metabolism cages for 48 h to monitor urinary and fecal excretion of the label. Adaptation to dietary o-phenylphenol appeared to increase the urinary excretion of orally administered U-14C-oxalic acid when food and water were available during urinary and fecal collections. Adaptation to dietary saccharin had little effect on urinary oxalate levels when compared to control animals. These results indicate that changes in urinary oxalate levels should be more carefully studied in connection with potential urinary bladder carcinogens to avoid the possibility of bladder irritation by increased urinary oxalate excretion.     

Absorption of oxalic acid in rats by means of a 14C method.

13 rats received a daily dose of 0.5 ml of a 1% solution of 14C-marked sodium oxalate (specific activity 29 nCi/ml) administered in one application with a throat probe. Feces and urine were collected every 24 h and the amount of 14C-oxalate was determined by liquid scintillation counting. The average distribution for 13 rats during 7 days showed 25.2% of 14C-oxalate in the urine and 73.4% in the feces. The rate of absorption is considerably higher than values given in literature (2.6--12% urine). These results indicate that in the pathogenesis of calcium oxalate stone formation some possible significance must be attributed to the exogenic oxalate.     

Urinary guanidinoacetic acid excretion as an indicator of gentamicin nephrotoxicity in rats

The kidney is the main site of guanidinoacetic acid synthesis and excretion. The aim of this study was to examine whether urinary guanidinoacetic acid is a sensitive indicator for diagnosis of early-stage gentamicin nephrotoxicity. Early-stage renal injury was induced in rats by a single intravenous injection of 5, 10, or 30 mg/kg body weight gentamicin. Twenty-four hours after injection all rats were killed. Blood, urine and tissue guanidino compound concentrations were determined by high performance liquid chromatography. Glycine amidinotransferase activity in tissues was assayed according to the method of Pilsum. Urinary guanidinoacetic acid excretion was decreased in 5 mg/kg gentamicin-treated rats in comparison to that in control rats, whereas urine N-acetyl-beta-D-glucosaminidase activity and beta2-microglobulin were unchanged. Guanidinoacetic acid concentration and glycine amidinotransferase activity in the kidney were significantly decreased in 5, 10, and 30 mg/kg gentamicin-treated rats; the decreases were dose-dependent. These results suggest that the urine guanidinoacetic acid concentration is a more sensitive indicator of renal injury than conventional indicators such as urine N-acetyl-beta-D-glucosaminidase and beta2-microglobulin.     

Bone response to mechanical loading in adult rats with collagen-induced arthritis

To elucidate the effects of inflammation on the response of bone to mechanical stress, we performed experiments using a rat with collagen-induced arthritis (CIA) model. Six-month-old female Wistar rats were used in the experiment. Bovine type II collagen sensitization and additional sensitization after 1 week were preformed in all CIA groups. Loads were applied using a four-point bending device. The right tibia was loaded in both CIA and control (CONT) groups at 35 N (low groups), 40 N (medium groups), or 47 N (high groups) for 36 cycles at 2 Hz three times per week for 3 weeks. Histomorphometrical data were collected from the periosteal and endosteal surfaces of the tibia in all rats. The tibia periosteal surface was subdivided into lateral and medial surfaces. Formation surface (FS), mineral apposition rate (MAR) and bone formation rate (BFR) were calculated. At lateral surface of periosteal surface, all three parameters showed significant differences between the loaded and nonloaded tibiae. All these parameters were significantly lower in CIA groups than in CONT groups, and interaction was seen between applied loading and CIA. There was a significant correlation between peak strain and the right-left difference of FS in the CONT groups. At medial surface of periosteal surface, there were force-related increase in FS, MAR, and BFR on the loaded side in both CIA and CONT groups, except MAR in the CONT group. All three parameters showed significant differences between the loaded and nonloaded tibiae. At endocortical surface, force-related increase was observed only in FS on the loaded side in CONT groups, and FS was significantly higher on the loaded side than the nonloaded side. CIA lowered all three parameters significantly. We examined the response to mechanical loading on the tibia in untreated CONT rats and rats with CIA by bone histomorphometry, and found that arthritis suppressed bone formation induced by mechanical loading.     

Cryoablative response of prostate cancer cells is influenced by androgen receptor expression

OBJECTIVE

To investigate in prostate cancer cells the consequences of androgen‐insensitivity (AI) development on the cellular and molecular responses to freezing, as a challenge in prostate cancer treatment occurs when the androgen‐sensitive (AS) phenotype switches to an AI phenotype, the latter of which is often refractory to many therapies.

MATERIALS AND METHODS

PC‐3 (AI) and LNCaP (AS) were each genetically altered to express the opposite phenotype and subjected to an in vitro freezing model. Viability, caspase inhibitor and Western blot studies were used to determine the basis of the differential responses of AI and AS cells.

RESULTS

LNCaP high‐passage cells, formed by repeated passage of LNCaP (AS) cells, were AI and showed a phenotypic shift to freeze resistance matching the freeze response of PC‐3 cells (AI). While stably transfected androgen receptor (AR)‐transfected cells (PC‐3 AR) had a freezing sensitivity similar to that of the LNCaP (AS) cell line. Importantly, AI cell lines survived and recovered from freezing exposure to temperatures as low as ?40 °C whereas AS cell lines did not. Caspase inhibition studies and related fluorescent probes showed an elevated level of apoptotic involvement in both AS cell lines after freezing compared with their AI counterparts. Western blot analysis showed that AR expression was modified after exposure to freezing.

CONCLUSION

This study suggests that AS cancers may be far more sensitive to a freezing insult and this might be linked to elevated apoptosis and caspase activity. As such, cryoablation may prove most effective in cancer cells that have not yet progressed to a more resistant AI phenotype, but both generic variants can be fully ablated at sufficiently low temperatures.     

Oral calcium loading test and response to diuretics in normal taiwanese school children

To investigate possible mechanisms of increased urinary calcium excretion and increased prevalence of urolithiasis in 16- to 20-year-old children, oral calcium loading and diuretic tests were performed in 120 normal children in three age groups (7–8, 12–13, and 17–18 years of age). Urinary calcium/creatinine ratios and 24-h urinary calcium excretion were significantly increased following the oral calcium loading test in 17- to 18-year-olds compared with the two younger age groups. Oral furosemide resulted in increased urinary calcium excretion in the 17- to 18-year age group, while hydrochlorothiazide was less effective in reducing urinary calcium excretion in this age group. These results suggest that increased intestinal calcium absorption and decreased renal tubular reabsorption of calcium in 17- to 18-year-olds may be contributing factors in the increased prevalence of nephrolithiasis in older Taiwanese children.     

草酸和草酸钙结晶损伤肾小管上皮细胞的差异蛋白质组学研究

目的 分析并鉴定草酸和一水草酸钙(COM)结晶损伤人肾小管上皮细胞(HK-2)后细胞蛋白质谱的表达变化,探讨肾小管上皮细胞受损在肾结石形成中的可能作用.方法 体外培养正常HK-2细胞至90%融合后,换无血清培养基,随机分为2组.实验组培养基内加入2 mmol/L草酸+200 mg/L COM结晶,37 ℃孵育.分别抽提2组细胞的总蛋白,双向凝胶电泳结合液相色谱-电喷雾离子阱质谱(LC-ESI-MS/MS)技术对2组中差异表达的蛋白质进行分离和鉴定.蛋白印迹法对鉴定出的蛋白进行验证.结果 成功建立细胞总蛋白的双向凝胶电泳图谱,经软件分析和质谱鉴定出差异蛋白质12个:FK506结合蛋白4、α-烯醇酶、M2型丙酮酸激酶、ATP合成酶α亚单位、3′,5′-二磷酸核苷酸酶1、核磷蛋白2、L-乳酸脱氢酶B、芽胞发芽蛋白3、Cofilin-1、Fascin、40S核糖体蛋白S17和胞液氨基肽酶1.差异蛋白涉及细胞能量代谢、细胞增殖、凋亡、钙离子通道活性调控、细胞运动及信号转导等多种生理活动.蛋白印迹法检测示HK-2细胞损伤后ENO1蛋白表达上调,而Cofilin-1表达下调,证实双向凝胶电泳和质谱分析可靠.结论 高浓度草酸和COM结晶可使正常人HK-2细胞蛋白表达发生改变,这些差异表达蛋白既可起到细胞的自我保护作用,又可能通过相应途径在肾结石的形成中起重要作用.

Abstract：

Objective To analyze and identify the differentially expressed proteins in human renal tubular epithelial cells (HK-2) after injury caused by oxalic acid and calcium oxalate monohydrate (COM) crystal, and to explore the potential role of renal tubular cell injury in kidney stone formation.Methods Normal HK-2 cells were cultured in vitro and the culture medium was changed with serum-free medium after cell growth to confluence. Oxalic acid and COM crystals (final concentration at 2 mmol/L and 200 mg/L, respectively) were added in the experimental group. Cells in both groups were then incubated at 37 ℃ for 12 h. The extracted proteins from both groups were separated by two dimensional electrophoresis followed by analysis, and the differentially expressed proteins were identified by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Two identified proteins were then verified by western blot. Results Reproducible two dimensional gel images of the proteins from both groups were successfully obtained. By using LC-ESI-MS/MS, 12 proteins: FK506-binding protein 4, isoform alpha-enolase of alpha-enolase, isoform M1 of pyruvate kinase isozymes M1/M2, ATP synthase subunit alpha, isoform 1 of 3′(2′), 5′-bisphosphate nucleotidase 1, isoform 2 of nucleophosmin, L-lactate dehydrogenase B chain, Budding uninhibited by benzimidazoles 3, Cofilin-1, Fascin, pyIsoform 1 of cytosol aminopeptidase, were identified. The deferentially expressed proteins were related to cellular processes including energy metabolism, cell multiplication, apoptosis, Ca2+ channel activity regulation, cell movement and signal transduction. Western blot verified that higher ENO1 but lower Cofilin-1 expressed in HK-2 cells after the injury. Conclusions High level oxalic acid and COM crystals can cause protein expression profile changes in normal human HK-2 cells. The changes of protein expression may not only protect HK-2 cells from being injured, but also be related to kidney stone formation.     

Cerebral pressure autoregulation is intact and is not influenced by hypothermia after traumatic brain injury in rats

In head-injured patients and experimental traumatic brain injury (TBI), important cerebrovascular abnormalities include decreases in cerebral blood flow (CBF) and impairment of cerebral pressure autoregulation. We evaluated CBF and pressure autoregulation after fluid percussion injury (FPI) and hypothermia in rats with the hypothesis that hypothermia would ameliorate changes in posttraumatic CBF. Male Sprague-Dawley rats, intubated and mechanically ventilated, were prepared for parasagittal FPI (1.8 atm) and laser Doppler CBF flow (LDF) measurement. The abdominal aorta was cannulated for rapid removal and reinfusion of blood. Baseline autoregulatory testing in all groups consisted of LDF measurements at normothermia and a mean arterial pressure (MAP) of 100 mm Hg, followed by randomly ordered changes of MAP to 80, 60, and 40 mm Hg. Animals were then randomized to one of five groups: normothermic control without FPI; normothermia with FPI; hypothermic control (32 degrees C) without FPI; hypothermia initiated before FPI; and hypothermia initiated immediately after FPI injury. For each group, a complete, randomly ordered autoregulatory sequence was performed at 30 and 60 min after FPI or sham TBI. In a second study, rats were prepared identically, maintained at normothermic temperatures and autoregulation was tested before and after TBI using a set of randomly ordered levels of hypotension or using progressive reductions in MAP (i.e., 80, 60, 40 mm Hg) with the hypothesis that the technical manner and timing of decreasing of the blood pressure would effect CBF after TBI. Due to high acute mortality, the group in which hypothermia was induced before FPI was excluded from the analysis. At baseline, autoregulation was similar in all groups. There was no change in CBF or autoregulation in the normothermic control group at 30 and 60 min. In the other groups at 30 and 60 min, there was a similar, statistically significant decrease in absolute CBF (i.e., a decrease of 27-57% of baseline values), but pressure autoregulation was intact except at the lowest blood pressure tested at 60 min, where there was a slight improvement in the hypothermic group. Thus, in these experiments, absolute CBF decreased with hypothermia and FPI, while neither hypothermia nor FPI significantly altered autoregulation. In the second study, autoregulatory function was not different before TBI when comparing random and sequential blood pressure changes, but, when comparing the groups after TBI at the 60 mm Hg blood pressure level, CBF was significantly lower in the sequential group than in the random order group. This suggests that the mechanism of creating hypotension, whether random or sequential, significantly affects the measurement of CBF and autoregulation after TBI in rats.     

The response to cyclophosphamide in steroid-sensitive nephrotic syndrome is influenced by polymorphic expression of glutathion-S-transferases-M1 and -P1

Glutathione-S-transferases (GST) play a central role in the inactivation of toxic drugs like cyclophosphamide (CP). These enzymes depict several polymorphisms with altered activity, and it has been shown that different polymorphisms influence the risk of malignancies and the outcome after chemotherapy. To prove the hypothesis that CP efficacy in children with nephrotic syndrome is influenced by polymorphic expression of GSTs, the genotype of 26 patients was analyzed and correlated with the outcome after CP treatment. All 26 children with steroid-sensitive nephrotic syndrome and frequent relapses or steroid dependency were treated with CP at a mean age of 6.7±4.0 years. CP was given in a dose of 2 mg/kg/day for 12±1 week. GST-M1, GST-P1 and GST-T1 polymorphisms were detected by PCR. In patients with GST-M1 null polymorphism, a significantly better rate of sustained remission was seen than in patients with the heterozygous or homozygous GST-M1 wildtype (0 versus 29%, P <0.01). In contrast, children with GST-P heterozygous or homozygous polymorphism had a significantly lower rate of sustained remission compared to homozygous wildtype (7 versus 38%, P <0.02). The GST-T1 genotype did not influence the outcome after CP treatment (P =0.32). Patients with the combination of GST-M1 null and GST-P1 wildtype did not relapse in 50%, compared to 6% in other children (P <0.01). We conclude that the polymorphic expression of GST-M1 and -P1 did significantly influence the long-term remission rate after CP treatment of steroid-sensitive nephrotic syndrome in children. Whereas GST-M1 null will increase cyclophosphamide efficacy, GST-P1 polymorphism seems to be related to enhanced susceptibility to further relapses.A part of this work was presented at the 31st meeting of the Arbeitsgemeinschaft Pädiatrische Nephrologie (APN), Vienna, Austria, 22–24 March 2001, and at the 12th congress of the International Pediatric Nephrology Association (IPNA), Seattle, Wash., 1–5 September 2001, and published in abstract form (Nieren- und Hochdruckkrankheiten 30:94, 2001, and Pediatric Nephrology 16:C123, 2001)     

Femoral bone structural geometry adapts to mechanical loading and is influenced by sex steroids: the Penn State Young Women's Health Study

We used 10 years of longitudinal data from Penn State Young Women's Health Study to explore predictors of adult bone structural geometry and strength. One hundred twelve participants were enrolled in the study at age 12. We report findings on the 76 participants who remained in the study for 10 years. Measurements were recorded biannually for the first 4 years and annually thereafter. Proximal femur DXA scans (Hologic QDR 2000) were taken from 17-22 years and analyzed using a hip structure analysis program to assess areal bone mineral density (BMD, g/cm2), subperiosteal width, cortical thickness, bone cross-sectional area (CSA), and section modulus (Z) at the narrow neck and femoral shaft. Total body lean mass (g) was measured with DXA total body scans. Nutrition, anthropometry, and sex steroids [testosterone (T) and estradiol (E2)] were measured from ages 12-22 years. Multiple regression models were used to assess predictors of change in bone variables (17-22 years) and absolute bone values (average of age 21 and 22 years, n = 79). Neck Z (+3.1%) and width (+1.3%), but not BMD (-0.8%), increased significantly from age 17 to 22 years. At the shaft, all variables increased (+1.0-4.0%, P < 0.01). After controlling for baseline (age 17) height, weight and bone measurement, weight change (neck) or lean mass (shaft), and age of menarche were the primary predictors of change in bone strength. After controlling for height and weight, only lean mass predicted absolute young adult Z at both the neck (r2 = 0.48, P < 0.01) and the shaft (r2 = 0.67, P < 0.01). When lean mass was removed from the model, sports exercise score replaced lean mass as a predictor of Z at both neck (r2 = 0.40, P < 0.01) and shaft (r2 = 0.60, P < 0.01) sites. For neck and shaft cortical thickness and BMD, both estradiol and sports score/lean mass were positive predictors (r2 = 0.15-0.40, P < 0.01). For neck bone width, testosterone levels (negative) and lean mass (positive) were significant (r2 = 0.48). Results were similar for each geometric variable at the shaft site. These data suggest that bone adapts its bending strength primarily to mechanical loading (represented by lean mass and sports exercise score) and that sex steroids are associated with bone geometric structure.     

Urinary excretion of guanidinoacetic acid in rats with diabetic nephropathy

Urinary guanidinoacetic acid (GAA) is a sensitive marker for gentamicin nephrotoxicity in rats. This study assesses the usefulness of GAA concentrations in the diagnosis of renal tubular injury in diabetic nephropathy. Serum, urine, and renal cortex samples were obtained from rats 1, 2, and 3 weeks after streptozotocin injection (65 mg/kg body weight). Guanidinoacetic acid levels were measured by high-performance liquid chromatography. N-acetyl-beta-D-glucosaminidase (NAG) activity in urine was determined by an enzymatic method. GAA levels in serum, urine, and renal cortex were significantly decreased in diabetic rats compared with those in control rats. In contrast, urinary NAG activity was significantly increased in diabetic rats. Decreases in serum, urine, and renal cortical GAA levels were attenuated by insulin treatment. These results indicate that a high serum glucose level may affect GAA synthesis in the renal cortex and that urinary GAA may be a clinically useful indicator of renal tubular injury in diabetic nephropathy.     

Methicillin-resistantStaphylococcus aureus proliferation in the rat gut is influenced by gastric acid inhibition and the administration of antibiotics

The author studied methicillin-resistantStaphylococcus aureus (MRSA) proliferation in the rat gut which was influenced by gastric acid inhibition and the administration of antibiotics. When male Wistar rats were bred by total parenteral nutrition (TPN), and were continuously administered famotidine 4 mg/kg per day, the gastric acidity was observed to decrease to pH 6.4±0.1. However, when they were bred by TPN, and histamine 4 mg/kg per hour was continuously administered, the gastric acidity was observed to increase to pH 1.9±0.4. MRSA was thus able to cross over to the small intestine only during the famotidine medication. If rats were intravenously administered latamoxef (LMOX) after an oral inoculation of MRSA, then the viable MRSA counts in the stomach, small intestine, and large intestine all decreased on day 4. In contrast, if the gastric acidity decreased and the rats were treated by an oral administration of kanamycin and metronidazole before an oral inoculation of MRSA and thereafter were administered LMOX, then the MRSA count significantly increased. It is thus concluded that a suppression of gastric acid and a great disorder of the intestinal flora is indispensable for the colonization of MRSA into the small intestine, while in vitro the propagation of MRSA requires a continuity of suppression absent in the bacterial flora.