The effect of physical activity on vitamin D: A systematic review and meta-analysis of intervention studies in humans.

Objectives: Cross-sectional studies demonstrate a positive association between higher physical activity and serum 25-hydroxyvitamin D (25(OH)D) concentration. However, whether this association is causal is unclear. We conducted a systematic review to identify intervention studies that examined the effect of physical activity on serum 25(OH)D concentration in humans. Study design: Systematic review and meta-analysis. Methods: We searched PubMed, Scopus and Web of Science to identify full-text peer-reviewed articles published in English from inception until January 2023. Eligible studies were randomised controlled trials or quasi-experimental studies. We used random effects meta-analysis to calculate the weighted mean difference (WMD) in the change in 25(OH)D concentration between physical activity and control groups. We used the revised Cochrane risk-of-bias tool for randomized trials (RoB 2) to assess the methodological quality of included studies. Results: We included 32 articles in the systematic review and 24 in the meta-analysis. The intervention varied from resistance and weight-bearing exercises (n = 13) to aerobic exercises (n = 10), moderate and moderate-to-vigorous exercises (n = 5), aquatic exercise (n = 2), and multicomponent traditional exercises (n = 2) (Tai Chi and Yijinjing). The WMD in 25(OH)D in the physical activity and control groups was 9.51 and 4.87, respectively (between-group mean difference 4.64, p = 0.002). However, the difference was only evident in studies that implemented the intervention outdoors (n = 3; between-group mean difference 17.33, p < 0.0001); when the intervention was indoors there was no significant effect of physical activity on 25(OH)D (n = 16; between-group mean difference 1.80, p = 0.113). Conclusions: This meta-analysis of physical activity interventions in humans showed that physical activity does not lead to increased 25(OH)D independently of time outdoors. However, most studies were under-powered, in many the exercise was low intensity, and vitamin D was not the primary outcome.

Extraction of maxillary teeth by dental students without palatal infiltration of local anaesthesia: a randomised controlled trial.

OBJECTIVE: Palatal infiltration of local anaesthesia (LA) for maxillary tooth extractions is painful. One of the techniques for reducing the discomfort of this injection is to avoid it altogether. Given enough time, LA administered only as buccal infiltration diffuses to reach and anaesthetise the palatal tissues. The aim of this double-blind randomised controlled trial was to test the hypothesis that buccal infiltration alone of LA by dental students should be adequate for maxillary tooth extractions. PATIENTS AND METHODS: Fifty adult patients presenting for single-tooth maxillary extractions were randomly allocated between two groups. The control group received palatal injections of 0.1 ml 2% lidocaine with 1:100,000 adrenaline, whilst the experimental group received a similar amount of saline (placebo). Extractions performed without further administration of LA were categorised as successful. RESULTS: Palatal infiltration of lidocaine with adrenaline was significantly more effective than saline (P = 0.002). Overall buccal infiltration alone was successful in 28% patients, with a 40% success rate in the posterior maxilla. CONCLUSION: Results suggest that dental students should, as a matter of routine, extract maxillary teeth with both buccal and palatal infiltration of LA, whilst buccal infiltration alone may be considered in the posterior maxilla.

Prevention of renal crystal deposition by an extract of Ammi visnaga L. and its constituents khellin and visnagin in hyperoxaluric rats.

In Egypt, teas prepared from the fruits of Ammi visnaga L. (syn. "Khella") are traditionally used by patients with urolithiasis. The aim of this study was to evaluate whether oral administration of an aqueous extract prepared from the fruits of A. visnaga as well as two major constituents khellin and visnagin could prevent crystal deposition in stone-forming rats. Hyperoxaluria was induced in male Sprague-Dawley rats by giving 0.75% ethylene glycol and 1% ammonium chloride via the drinking water. The Khella extract (KE; 125, 250 or 500 mg/kg) was orally administered for 14 days. The histopathological examination of the kidneys revealed that KE significantly reduced the incidence of calcium oxalate (CaOx) crystal deposition. In addition, KE significantly increased urinary excretion of citrate along with a decrease of oxalate excretion. Comparable to the extract, khellin and visnagin significantly reduced the incidence of CaOx deposition in the kidneys. However, both compounds did not affect urinary citrate or oxalate excretion indicating a mechanism of action that differs from that of the extract. For KE, a reasonably good correlation was observed between the incidence of crystal deposition, the increase in citrate excretion and urine pH suggesting a mechanisms that may interfere with citrate reabsorption. In conclusion, our data suggest that KE and its compounds, khellin and visnagin, may be beneficial in the management of kidney stone disease caused by hyperoxaluria but that it is likely that different mechanism of action are involved in mediating these effects.

Effects of an extract from Herniaria hirsuta on calcium oxalate crystallization in vitro.

OBJECTIVE: To evaluate the effectiveness of an extract obtained from Herniaria hirsuta on calcium oxalate crystallization in vitro. Materials and methods An extract was prepared from H. hirsuta at different concentrations (0.0625-1 mg/mL). Crystallization was induced in whole normal human urine samples in the absence or presence of the extract. Crystals generated in the urine were harvested and analysed by scanning electron microscopy. The nucleation and aggregation of calcium oxalate crystals were measured separately using spectrophotometric methods. The nucleation rate was followed at 620 nm after mixing calcium chloride and sodium oxalate solution at 37 degrees C, with stirring. The induction time in the presence of herb extract was compared with that of the control. The aggregation rate was also followed at 620 nm in a buffered solution containing calcium oxalate monohydrate crystals after stopping the stirring. The rate was evaluated by comparing the slope of turbidity in the presence of the extract with that of the control. RESULTS: The herb extract promoted the precipitation of calcium oxalate particles in whole urine. SEM showed that there were more crystals with increasing concentration of extract but that they were proportionally smaller. Moreover, the presence of herb extract favoured the formation of calcium oxalate dihydrate rather than monohydrate crystals. The extract inhibited calcium oxalate crystal aggregation. In an independent experiment, the herb extract was dialysed and filtered before inducing crystallization, to eliminate any fibrous particles and oxalate. The treated herb extract promoted more crystallization, especially at high concentrations. CONCLUSION: An extract of H. hirsuta promoted the nucleation of calcium oxalate crystals, increasing their number but decreasing their size. It also promoted the formation of calcium oxalate dihydrate crystals, despite the presence of calcium oxalate monohydrate particles. The extract may contain substances that inhibit calcium oxalate crystal aggregation. These properties of H. hirsuta might be beneficial in preventing kidney stone formation.

Membranes and their constituents as promoters of calcium oxalate crystal formation in human urine.

We have proposed that membranes of cellular degradation products are a suitable substrate for the nucleation of calcium oxalate (CaOx) crystals in human urine. Human urine is generally metastable with respect to CaOx. To demonstrate that cellular membranes present in the urine promote nucleation of CaOx we removed these substrates by filtration or centrifugation and induced crystallization by adding sodium oxalate, before and after filtration or centrifugation. In a separate experiment, membrane vesicles isolated from rat renal tubular brush border were added into the filtered or centrifuged urine before crystal induction. Crystals were counted using a particle counter. Urine, the pellet, and retentate were analyzed for the presence of membranes, lipids, and proteins. Lipids were further separated into different classes, identified, and quantified. Both filtration and centrifugation removed lipids, proteins, and membrane vesicles, causing a reduction in lipid and protein contents of the urine. More crystals formed in whole than in filtered or centrifuged urine. The number of crystals significantly increased when filtered urine was supplemented with various urinary components such as the retentate and phospholipids, which are removed during filtration. We also determined the urinary metastable limit with respect to CaOx. Filtration and centrifugation were associated with increased metastable limit which was reduced by the addition of membrane vesicles. These results support our hypothesis that urine normally contains promoters of CaOx crystal formation and that membranes and their constituents are the most likely substrate for crystal nucleation in the urine.

Temporal changes in mRNA expression for bikunin in the kidneys of rats during calcium oxalate nephrolithiasis.

Inter-alpha-inhibitor and other bikunin-containing proteins are synthesized in relatively large quantities by the liver. These proteins function as Kunitz-type serine protease inhibitors and appear capable of inhibiting calcium oxalate (CaOx) crystallization in vitro. Preliminary studies have shown that renal tubular epithelial cells synthesize bikunin in response to CaOx challenge. To examine this response in vivo, a sensitive reverse transcription-quantitative competitive template-PCR was developed to detect and quantify poly(A)+ -tailed bikunin mRNA expression in kidney tissue from normal rats and rats developing CaOx nephrolithiasis after challenge with ethylene glycol. Bikunin mRNA expression in rat liver tissue was assessed as a positive control. The expression of bikunin mRNA in liver did not differ significantly between normal control rats and experimental rats with induced hyperoxaluria and renal CaOx crystallization. In contrast, there were significant temporal increases in the levels of bikunin mRNA expression in rat kidneys during CaOx nephrolithiasis after challenge with ethylene glycol. Urinary excretion of bikunin-containing proteins seemed to increase concomitantly. These findings indicate an association between the induction of hyperoxaluria/CaOx nephrolithiasis and the expression of the bikunin gene in rat kidneys.

Association of urinary macromolecules with calcium oxalate crystals induced in vitro in normal human and rat urine.

This study was undertaken to identify proteins which are found associated with calcium oxalate crystals induced in vitro in normal human and rat urine. Crystallization was initiated by adding sodium oxalate individually to each urine sample without centrifugation and filtration. Crystals were collected and analyzed by scanning electron microscopy and X-ray diffraction. Crystal matrix proteins (CMPs) were obtained by demineralization of the crystals with ethylenediaminetetra-acetic acid (EDTA) and analyzed by western blotting technique for immunological identification. Crystals produced in human urine were found to be a mixture of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) while those produced in rat urine were exclusively COD. CMPs extracted from crystals in human urine comprised, in addition to prothrombin-related proteins, osteopontin and albumin. However, CMPs extracted from crystals in rat urine contained only osteopontin and albumin. Prothrombin-related proteins were found only in trace amounts. In a separate experiment, rat urine samples were supplemented with COM before inducing crystallization. Similar results were observed showing that CMP contained osteopontin, albumin and trace amounts of prothrombin-related proteins. We conclude that several urinary macromolecules including not only prothrombin-related proteins, but also osteopontin and albumin, become associated with CaOx crystals. The incorporation of these proteins in growing stones is not only due to the presence of gamma-carboxyglutamic acid as it was suggested for prothrombin-related proteins, but may be due to other factors such as urinary chemistry, presence of glutamic and aspartic acid residues, and calcium-binding sites.

Role of scanning electron microscopy and x-ray microanalysis in the identification of urinary crystals.

Urinary crystals can be identified by using analytical electron microscopic techniques of scanning electron microscopy and energy dispersive x-ray microanalysis. Crystal habit can be recognised by scanning electron microscopy and their chemical nature by elemental analysis. With a conventional detector the lightest element that can routinely be detected is sodium, but with a windowless or thin window detector even carbon can be detected. Thus almost all the commonly occurring urinary crystals including uric acid can be analysed by energy dispersive x-ray microanalysis.