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At least 307 records · Page 17Linked to original sources
PubMed1997

Serum aluminium levels of workers in the bauxite mines.

BACKGROUND/OBJECTIVE: Aluminium is produced from the mineral bauxite. Occupational exposure is reported during the industrial processing of aluminium and is associated with pulmonary and neurotoxicity. However, data on exposure and toxicity of workers in the open bauxite mining industry do not exist. Therefore, a study was performed to explore aluminium exposure in employees involved in this bauxite mining process in a Surinam mine. METHODS/DESIGN: A group of workers occupationally exposed to aluminium in an open bauxite mine were compared with a group of nonexposed wood processors. Serum aluminium was analyzed using atomic absorption spectrometry Data from the clinical chemistry of the blood and a questionnaire were used to explore determinants for aluminium exposure. RESULTS: No significant difference between serum aluminium in the exposed (4.4 +/- 2.0 micrograms/L, n = 27) and control group (5.1 +/- 1.5 micrograms/L, n = 27) was detected. For the serum concentration of the clinical chemical variables (calcium, citrate, and creatinine), a statistically significant difference was computed (p < or = 0.02) between the exposed and control group. All levels were slightly higher in the exposed group; no statistically significant correlations with serum aluminium were found. CONCLUSIONS: In this study, serum aluminium values were in the normal range, no significant difference between the groups could be detected despite long-term occupational exposure.

Adult↗
PubMed1985

"Shear induced platelet activation"--a critical reappraisal.

Platelets were found to be stimulated by high shear exposure for 5 minutes. Using a new technique, shear stresses up to 255 N/m2, acting for pathophysiological relevant intervals of milliseconds did not elicit active release of beta-TG, beyond the amount explained by LDH-monitored passive lysis. Neither the plasma level of ionized calcium (citrate vs heparin anticoagulation), nor a potent platelet inhibiting agent like PgI2 (20 nM) did significantly alter platelet responses to short acting high shear stress. Ultrastructural signs of activation could largely be suppressed by adding ADP-scavengers. Direct "shear induced platelet activation" appears rather unlikely and mostly reducible to secondary biochemical activation by mediators, probably adenine nucleotides, from a small percentage of passively shear-destroyed platelets. The extent of this secondary activation is largely a matter of experimental conditions.

Adenosine Diphosphate↗
PubMed1991

Effect of vitamin D supplementation on wintertime and overall bone loss in healthy postmenopausal women.

OBJECTIVES: To determine whether relative vitamin D deficiency during the winter months contributes to age-related bone loss and whether rates of change in hard- and soft-tissue mass vary during the year. DESIGN: Double-blind, placebo-controlled, 1-year trial in 249 women in which equal numbers of women were randomized to either placebo or 400 IU of vitamin D daily. All women received 377 mg/d of supplemental calcium largely as calcium citrate malate. PATIENTS: Healthy, ambulatory postmenopausal women with usual intakes of vitamin D of 100 IU/d. MEASUREMENTS: Duplicate spine and whole-body scans were done by dual energy x-ray absorptiometry at 6-month intervals that were timed to periods when 25-hydroxyvitamin D levels were highest and lowest. Period 1 was June-July to December-January and period 2 was December-January to the next June-July. Serum parathyroid hormone and plasma 25-hydroxyvitamin D levels were measured during periods 1 and 2. MAIN RESULTS: In the placebo group, spinal bone mineral density increased in period 1, decreased in period 2, and sustained no net change. Women treated with vitamin D had a similar spinal increase in period 1 (1.46% compared with 1.40% in placebo), less loss in period 2 (-0.54% compared with -1.22%, CI for the difference, 0.05% to 1.31%, P = 0.032) and a significant overall benefit (0.85% compared with 0.15%, CI for the difference, 0.03% to 1.37%, P = 0.04). In period 2, 25-hydroxyvitamin D levels were lower and parathyroid hormone levels were higher in the placebo than in the vitamin D group. Whole-body lean and fat tissue and bone mineral density varied during the year but did not change overall. CONCLUSIONS: At latitude 42 degrees, healthy postmenopausal women with vitamin D intakes of 100 IU daily can significantly reduce late wintertime bone loss and improve net bone density of the spine over one year by increasing their intake of vitamin D to 500 IU daily. A long-term benefit of preventing vitamin D insufficiency in the winter seems likely although it remains to be shown. Observed changes in bone as well as in fat and lean tissue appear to be related to season.

Absorptiometry, Photon↗
PubMed1999

Vulvodynia and vulvar vestibulitis: challenges in diagnosis and management.

Vulvodynia is a problem most family physicians can expect to encounter. It is a syndrome of unexplained vulvar pain, frequently accompanied by physical disabilities, limitation of daily activities, sexual dysfunction and psychologic distress. The patient's vulvar pain usually has an acute onset and, in most cases, becomes a chronic problem lasting months to years. The pain is often described as burning or stinging, or a feeling of rawness or irritation. Vulvodynia may have multiple causes, with several subsets, including cyclic vulvovaginitis, vulvar vestibulitis syndrome, essential (dysesthetic) vulvodynia and vulvar dermatoses. Evaluation should include a thorough history and physical examination as well as cultures for bacteria and fungus, KOH microscopic examination and biopsy of any suspicious areas. Proper treatment mandates that the correct type of vulvodynia be identified. Depending on the specific diagnosis, treatment may include fluconazole, calcium citrate, tricyclic antidepressants, topical corticosteroids, physical therapy with biofeedback, surgery or laser therapy. Since vulvodynia is often a chronic condition, regular medical follow-up and referral to a support group are helpful for most patients.

Adult↗
PubMed2001

[Study of renal function in infants diagnosed with renal pyelectasis in the first year of life].

OBJECTIVE: To evaluate glomerular and tubular function in a group of infants diagnosed with pyelectasis. PATIENTS AND METHODS: We studied 14 patients diagnosed with renal pelvis dilatation in-utero or during the first year of life. Creatinine concentrations, urinary excretion of calcium, citrate, oxalate, N-acetyl-D-glucosaminidase (NAG), microalbumin and maximum urine osmolality after administration of intranasal desmopressin were determined. The latter three variables were determined at diagnosis and at the end of follow-up. RESULTS: In all patients creatinine levels were normal. In six patients (42.9%) maximum urine osmolality values were abnormal. In four patients NAG/creatinine concentrations were elevated and in another four patients (28.6%) albumin urinary excretion was elevated. These anomalies tended to return to normal but, at the end of the study, three patients (21.4%) showed increased albuminuria and one (7.1%) showed persistently defective renal concentrating capacity. Ten patients showed metabolic urinary anomalies, potentially leading to the formation of stones (isolated hypercalciuria in five [35,7%], hyperoxaluria in two and hypocitraturia in one, and hypercalciuria associated with hyperoxaluria in two). CONCLUSIONS: All patients showed normal glomerular function. Some patients presented increased albuminuria and moderate tubular function abnormalities, both of which tended to return to normal. Although studies with greater numbers of patients are needed, we propose that pyelectasis maybe a predictor of risk for lithiasis at later stages of life.

Biomarkers↗
PubMed1993

Effects of meal on the pharmacokinetics of fluoride from oral monofluorophosphate.

A two-treatment cross-over study was conducted on 8 Caucasian male healthy volunteers aged between 26 and 32 years in order to determine the influence of a standard meal on the bioavailability and pharmacokinetics of fluoride after a single oral administration of tablets containing the equivalent of 10 mg fluoride as sodium monofluorophosphate (Na-MFP, CAS 10163-15-2) in a fixed combination with 300 mg Ca as calcium gluconate and calcium citrate. The meal provoked a significant delay of the appearance of fluoride in blood (from 4 to 11 min), a slowing of the absorption rate, a prolongation of tmax (from 34 to 146 min), a decrease of Cmax (from 369 to 122 ng/ml) and a prolongation of the Mean Residence Time (from 7.1 to 9.1 h). However, the amount of fluoride entering in the systemic circulation was not affected by the meal, as shown by the ANOVA on the AUC and on the cumulated urinary excretion of fluoride in the 48 h following the administration of Na-MFP. It is concluded that appropriate meals do not influence the amount of absorbed fluoride from Na-MFP, and that they modify the rate of absorption with pattern that may improve the safety and possibly also the efficacy of Na-MFP.

Administration, Oral↗
PubMed1997

[Long-term follow-up study of bone mineral density in a patient with adult idiopathic Fanconi syndrome].

A 64-year-old woman complaining of severe lumbar pain was admitted to our hospital because of the finding of pre-existing mitral valve regurgitation on examination. Laboratory data revealed the proximal type of renal tubular acidosis, renal glucosuria, phosphaturia, generalized aminoaciduria and low-molecular-weight proteinuria. She did not have any cause of these tubular dysfunctions, and was diagnosed as adult idiopathic Fanconi syndrome. Dual energy X-ray absorptiometry (DEXA) revealed a reduction of bone mineral density in the lumbar spine to about 65% of the age-and gender-matched control value. Alkali agents (sodium citrate and potassium citrate), calcium lactate and 1 alpha-hydroxyvitamin D3 were administered. Bone mineral density estimated with DEXA improved with a reduction of serum alkali phosphate and disappearance of lumbar pain, and was restored to 82% of the age-and gender-matched control value after about 30 months of treatment. DEXA is useful for the long-term follow-up study of bone mineral density in a patient with Fanconi syndrome.

Absorptiometry, Photon↗
PubMedDate not supplied

[Age-related characteristics of the effect of deafferentation of the mandible on the metabolism of sulfate, citrate, phosphorus and calcium in the bones].

Mineral metabolism in the bones of 1- and 3-month rats reacts to a different extent to cutting the lower alveolar nerve. After deafferentation of the lower jaw, the decrease in the intensity of incorporation of the intraperitoneally injected [3-14C]-citrate and [35S]-sulphate in the bones is more significant in 1-month animals as compared to that in older ones. Deafferentation increased utilization of Na2H32PO4 and 45CaCl2 in the bones of younger rats, but decreased incorporation of 32P and remained unchanged incorporation of 45Ca in 3-month animals.

Aging↗
PubMed1993

Alkali absorption and citrate excretion in calcium nephrolithiasis.

The role of net gastrointestinal (GI) alkali absorption in the development of hypocitraturia was investigated. The net GI absorption of alkali was estimated from the difference between simple urinary cations (Ca, Mg, Na, and K) and anions (Cl and P). In 131 normal subjects, the 24 h urinary citrate was positively correlated with the net GI absorption of alkali (r = 0.49, p < 0.001). In 11 patients with distal renal tubular acidosis (RTA), urinary citrate excretion was subnormal relative to net GI alkali absorption, with data from most patients residing outside the 95% confidence ellipse described for normal subjects. However, the normal relationship between urinary citrate and net absorbed alkali was maintained in 11 patients with chronic diarrheal syndrome (CDS) and in 124 stone-forming patients devoid of RTA or CDS, half of whom had "idiopathic" hypocitraturia. The 18 stone-forming patients without RTA or CDS received potassium citrate (30-60 mEq/day). Both urinary citrate and net GI alkali absorption increased, yielding a significantly positive correlation (r = 0.62, p < 0.0001), with the slope indistinguishable from that of normal subjects. Thus, urinary citrate was normally dependent on the net GI absorption of alkali. This dependence was less marked in RTA, confirming the renal origin of hypocitraturia. However, the normal dependence was maintained in CDS and in idiopathic hypocitraturia, suggesting that reduced citrate excretion was largely dietary in origin as a result of low net alkali absorption (from a probable relative deficiency of vegetables and fruits or a relative excess of animal proteins).

Acidosis, Renal Tubular↗
PubMed2003

Association between vitamin D receptor gene polymorphisms and tubular citrate handling in calcium nephrolithiasis.

OBJECTIVES: Hypocitraturia is a risk factor for calcium nephrolithiasis. 1,25(OH)2D3 influences renal citrate handling and enhances citraturia. The aim of this study was to evaluate the relationship between vitamin D receptor (VDR) allelic variant and urinary citrate excretion in recurrent stone formers (SF) patients. DESIGN: Case-control study. SUBJECTS: A total of 220 recurrent calcium oxalate SF patients and 114 healthy control (C) subjects were enrolled for this study. Subjects with urinary tract infections, hyperparathyroidism, cystinuria >70 micromol/24 h, gouty diathesis, renal tubular acidosis, renal failure, chronic diarrhoeal states, intake of thiazide diuretics, angiotensin-converting enzyme (ACE)-inhibitors, glucocorticoids or oestrogens were excluded. A standard constant diet was given for 7 days. The 24-h urinary citrate excretion and the active tubular reabsorption of filtered citrate (Rcit) were evaluated. Hypocitraturia was defined as a urinary citrate excretion lower than 1.7 mmol day-1. Stone formers patients and C were genotyped for BsmI and TaqI VDR alleles. Contingency table chi-square tests were used to compare genotype frequencies in hypocitraturic SF patients, normocitraturic SF and C. RESULTS: The prevalence of hypocitraturia in SF patients was 32.7% (72 of 200). Hypocitraturia in these patients resulted from excessive Rcit of a normal load of citrate. We found a different distribution (P < 0.05) of BsmI and TaqI VDR genotypes in hypocitraturic SF patients compared with normocitraturic SF and C. In particular, the prevalence of bb and TT VDR genotypes in hypocitraturic SF was significantly higher than in normocitraturic SF and C. CONCLUSIONS: These results point to a genetic association between BsmI and TaqI VDR polymorphisms and idiopathic hypocitraturia in calcium-oxalate recurrent SF patients.

Adult↗
PubMed1983

Composition and ultrastructure of calcium phosphate-citrate complexes in bovine milk systems.

The present studies show that the colloidal calcium phosphate of cows' milk has a (Ca + Mg)/Pi ratio of 1.67 (+/- 0.10; n = 22) and contains citrate, Mg and Zn at molar ratios to Ca averaging 0.05, 0.03 and 0.003, respectively. The composition of the natural colloidal phosphate of milk is similar to the precipitates formed by neutralization of ultrafiltrates obtained from acidified milks, and to that of the calcium phosphate-enriched fraction produced by extensive enzymic hydrolysis of the casein micelles in milk. Examination by electron microscopy of these artificial preparations of milk calcium phosphate revealed in both a very fine and uniform substructure which consisted of granules having an average, true diameter of approx. 2.5 nm. The size and shape of these tiny granules closely resemble the morphologies reported for the colloidal phosphate particles in native casein micelles, as well as for the subunits of amorphous calcium phosphate observed during calcification in other biological systems such as mitochondria and bone.

Animals↗
PubMed1985

Sodium, potassium, calcium, magnesium, zinc, citrate and chloride content of human prostatic and seminal fluid.

The ionic composition of human prostatic fluid varied greatly between individuals, reflecting the secretory activity of the gland and the presence or absence of prostatic inflammatory disease. In normal prostatic fluid the major anion was citrate, while chloride concentrations were lower. Their counterions were mainly sodium and potassium, together with calcium, magnesium and zinc. Prostatic secretions from men with prostatitis comprised mainly sodium and chloride. The electrolytes were closely correlated to each other (except for sodium, which was essentially invariant at about 145 nm). The molar changes per mole of citrate were about 0.52, potassium; -0.53, chloride; 0.17, calcium; 0.14, magnesium; and 0.09, zinc. The pH was also associated with citrate, decreasing from 8.0 to 6.2 as the citrate increased. These various ionic changes can be explained as responses to citrate secretion, without the need to propose specific transport mechanisms for the other ions measured. The marked effect of prostatic inflammation on the composition of prostatic fluid can be seen as being due mainly to decreased secretion rather than active modification.

Calcium↗
PubMed1995

Idiopathic calcium oxalate urinary lithiasis: usefulness of Parks' and Tiselius' indices in the evaluation of the risk of stone formation.

Different indices of the risk of urinary calcium oxalate crystallization were compared to determine their usefulness in detecting the stone-formers particularly prone to recurrence. Urine volume and calcium, oxalate, citrate, magnesium or creatinine were determined in 55 patients presenting with an idiopathic calcium oxalate urolithiasis, as well as in 50 control subjects. On 24-hour urine samples, these elements allowed for the calculation and comparison of different indices of lithogenous risk as proposed by Parks and Tiselius. Both Parks' indices and the urinary citrate-calcium ratio varied significantly between the two groups, but conversely Tiselius' indices were statistically comparable. The three Tiselius' indices taking the 24-hour urine volume into account were also strongly correlated. Parks' index and the urinary citrate-calcium ratio are highly discriminating and potentially relevant to select the stone-formers with a high risk of relapse. Tiselius' indices basically reflect urinary calcium oxalate saturation, and can only be used clinically to control the treatment interfering with this. In this respect, the formula based simply on urine volume, calcium and oxalate over 24 h (Ca0.71.Ox.V-1.2) appears to be sufficient.

Adolescent↗