Undetectable vitamin D3 in equine skin irradiated with ultraviolet light

Vitamin D requirements for most animals are expected to be fulfilled through daily exposure of the skin to solar ultraviolet B radiation. The synthesis of vitamin D3 in skin depends on different factors including melanin pigmentation, the amount of UVB radiation reaching the skin, type of clothing/hair coat, latitude and altitude, season, and time of day. Alternatively vitamin D2 may be obtained from UVB irradiated pasture species. Recent studies have shown that in unsupplemented grazing horses 25-hydroxyvitamin D2 is the predominant form of vitamin D in plasma, and that 25OHD3 is undetectable suggesting horses may rely on diet to obtain vitamin D. In order to mimic the natural environment of skin to sunlight exposure, five equine and two ovine devitalized skin samples were irradiated with 5 J/cm2 of UVB light followed by measurement of 7-dehydrocholesterol (7-DHC) and vitamin D3 concentrations using reverse-phase high pressure liquid chromatography (HPLC). HPLC revealed the presence of 7-DHC in the skin of both horses and sheep. Vitamin D3 was undetectable in both ovine and equine skin prior to irradiation, but after irradiation with UVB light, ovine skin showed an increase in vitamin D3 concentration (mean 0.16 ± 0.07 µg/g), whereas vitamin D3 was undetectable in equine skin. These results provide additional evidence that horses make negligible quantities of vitamin D3 in their skin after exposure to UVB light and may therefore rely on their diet as a primary source of vitamin D.fals

Does blood contamination of urine compromise interpretation of the urine protein to creatinine ratio in dogs?

Aims: To determine the effect of contamination of urine with 0–5% blood, varying in haematocrit and protein concentrations, on the urine protein to creatinine ratio (UPC) in dogs, and to determine whether the colour of urine can be used to aid interpretation of UPC results. Methods: Urine samples were collected by free catch from 18 dogs, all of which had UPC <0.2. Venous blood samples were also collected from each dog, and the blood from each dog was added to its own urine to produce serial concentrations of 0.125–5% blood. The colour of each urine sample was recorded by two observers scoring them as either yellow, peach, orange, orange/red or red. Protein and creatinine concentrations were determined, and dipstick analysis and sediment examination was carried out on each sample. Based on colour and dipstick analysis, samples were categorised as either having microscopic, macroscopic or gross haematuria. A linear mixed model was used to examine the effect of blood contamination on UPC. Results: The uncontaminated urine of all 18 dogs had a UPC 0.5. For 108 samples with macroscopic haematuria the UPC was >0.5 in 21 samples (19.4 (95% CI = 13.1–27.9)%), and for 54 samples with gross haematuria 39 (72 (CI = 59.1–82.4)%) had a UPC >0.5. No samples had a UPC >2.0 unless the blood contamination was 5% and only 3/18 (17%) samples at this blood contamination concentration had a UPC >2.0. Conclusions and clinical relevance: This study showed that while blood contamination of ≥0.125% does increase the UPC, if the urine remains yellow (microscopic haematuria), then there is negligible chance that a UPC >0.5 will be solely due to the added blood. In that scenario, attributing the proteinuria present to the haematuria in the sample would be inappropriate. However blood contamination that results in discolouration of the urine sample from yellow to red (indicating macroscopic or gross haematuria) could increase the UPC above the abnormal range and would need to be considered as a differential for the proteinuria. Thus knowledge of urine colour, even if limited to simple colour scores (yellow, discoloured, red) could be utilised to aid interpretation of the UPC in samples with haematuria

Altered cerebrospinal fluid clearance and increased intracranial pressure in rats 18 h after experimental cortical ischaemia

oai:repository.derby.ac.uk:qz09zOedema-independent intracranial pressure (ICP) rise peaks 20–22-h post-stroke in rats and may explain early neurological deterioration. Cerebrospinal fluid (CSF) volume changes may be involved. Cranial CSF clearance primarily occurs via the cervical lymphatics and movement into the spinal portion of the cranio-spinal compartment. We explored whether impaired CSF clearance at these sites could explain ICP rise after stroke. We recorded ICP at baseline and 18-h post-stroke, when we expect changes contributing to peak ICP to be present. CSF clearance was assessed in rats receiving photothrombotic stroke or sham surgery by intraventricular tracer infusion. Tracer concentration was quantified in the deep cervical lymph nodes ex vivo and tracer transit to the spinal subarachnoid space was imaged in vivo. ICP rose significantly from baseline to 18-h post-stroke in stroke vs. sham rats [median = 5 mmHg, interquartile range (IQR) = 0.1–9.43, n = 12, vs. −0.3 mmHg, IQR = −1.9–1.7, n = 10], p = 0.03. There was a bimodal distribution of rats with and without ICP rise. Tracer in the deep cervical lymph nodes was significantly lower in stroke with ICP rise (0 μg/mL, IQR = 0–0.11) and without ICP rise (0 μg/mL, IQR = 0–4.47) compared with sham rats (4.17 μg/mL, IQR = 0.74–8.51), p = 0.02. ICP rise was inversely correlated with faster CSF transit to the spinal subarachnoid space (R = −0.59, p = 0.006, Spearman’s correlation). These data suggest that reduced cranial clearance of CSF via cervical lymphatics may contribute to post-stroke ICP rise, partially compensated via increased spinal CSF outflow

The effect of the degree of blood contamination of urine on the interpretation of the urinary protein creatinine ratio

The interpretation of the urinary protein to creatinine ratio(UPC) in urine samples with concurrent hematuria can be confusing, as blood may increase the protein level measured in the urine. To mimic hematuria, blood from 18 dogs was added to their own urine sample in increasing levels (from 0 to 5%) to determine whether the urine color for varying degrees of blood contamination can be utilized to aid interpretation of the validity of the UPC results. For each urine sample, urinary protein and creatinine were measured biochemically, urine dipstick analysis, specific gravity by refractometry and microscopic sediment examination were performed, and the urine color was visually assessed. A complete blood count (CBC) and serum biochemistry panel were performed on each dog. Blood contamination of the urine that did not result in a visible change in color of the urine sample from yellow (i.e., microscopic hematuria) did not increase the UPC above the normal range of <0.5. As such, in the presence of microscopic hematuria, the UPC level in yellow urine (with no evidence of concurrent urinary tract inflammation) should be considered valid. Thus, the practice of discouraging UPC assessment in animals with microscopic hematuria should be discontinued. However, hematuria that results in a visible color change from yellow may increase the UPC above 0.5. In this situation hematuria would need to be considered as a differential diagnosis for the proteinuria

The effect of blood contamination of urine on the interpretation of the urinary protein : creatinine ratio in the dog

The interpretation of the urinary protein : creatinine ratio (UPC) in urine samples with concurrent haematuria can be confusing, as blood may increase the protein level measured in the urine.\ud \ud The objectives of this experiment were:\ud \ud To determine if urinary blood contamination affects the UPC level.\ud \ud To determine whether urine sample colour can aid interpretation of the UPC in blood contaminated urine