A novel method for concentrating urinary type IV collagen based on precipitation with polyethylene glycol: application to its measurement by enzyme immunoassay

Collagen: A review on its sources and potential cosmetic applications

Collagen is a fibrillar protein that conforms the conjunctive and connective tissues in the human body, essentially skin, joints, and bones. This molecule is one of the most abundant in many of the living organisms due to its connective role in biological structures. Due to its abundance, strength and its directly proportional relation with skin aging, collagen has gained great interest in the cosmetic industry. It has been established that the collagen fibers are damaged with the pass of time, losing thickness and strength which has been strongly related with skin aging phenomena [Colágeno para todo. 60 y más. 2016. http://www.revista60ymas.es/InterPresent1/groups/revistas/documents/binario/ses330informe.pdf.]. As a solution, the cosmetic industry incorporated collagen as an ingredient of different treatments to enhance the user youth and well-being, and some common presentations are creams, nutritional supplement for bone and cartilage regeneration, vascular and cardiac reconstruction, skin replacement, and augmentation of soft skin among others [J App Pharm Sci. 2015;5:123-127]. Nowadays, the biomolecule can be obtained by extraction from natural sources such as plants and animals or by recombinant protein production systems including yeast, bacteria, mammalian cells, insects or plants, or artificial fibrils that mimic collagen characteristics like the artificial polymer commercially named as KOD. Because of its increased use, its market size is valued over USD 6.63 billion by 2025 [Collagen Market By Source (Bovine, Porcine, Poultry, Marine), Product (Gelatin, Hydrolyzed Collagen), Application (Food & Beverages, Healthcare, Cosmetics), By Region, And Segment Forecasts, 2014 - 2025. Grand View Research. http://www.grandviewresearch.com/industry-analysis/collagen-market. Published 2017.]. Nevertheless, there has been little effort on identifying which collagen types are the most suitable for cosmetic purposes, for which the present review will try to enlighten in a general scope this unattended matter.

Urinary markers of glomerular injury in diabetic nephropathy

Diabetic nephropathy, the leading cause of renal failure worldwide, affects approximately one-third of all people with diabetes. Microalbuminuria is considered the first sign and the best predictor of progression to renal failure and cardiovascular events. However, albuminuria has several limitations. Therefore, earlier, more sensitive and specific biomarkers with greater predictability are needed. The aim of this paper is to discuss the current literature on biomarkers of glomerular injury that have been implicated in diabetic kidney disease.

Decreased urinary concentrations of type IV collagen in amyotrophic lateral sclerosis

OBJECTIVES

Type IV collagen (IV-C) abnormalities of skin and serum have been reported in patients with amyotrophic lateral sclerosis (ALS). However, there has been no study of urinary IV-C in ALS. The present study investigates urinary IV-C and the relation to its skin content in patients with ALS.

MATERIAL AND METHODS

We studied IV-C immunoreactivity of skin and measured urinary levels of IV-C in ALS patients and controls.

RESULTS

The basement membrane as well as blood vessels of skin in ALS patients was weakly positive for IV-C as compared with those of controls. Immunostaining became even weaker as ALS progressed. The urinary level of IV-C in ALS patients was significantly decreased as compared to diseased controls (P<0.001) and healthy controls (P<0.001), and was negatively and significantly associated with duration of symptoms (r=-0.85, P<0.001). There was an appreciable positive correlation between urinary IV-C levels and the density for IV-C immunoreactivity in ALS patients (r=0.84, P<0.01).

CONCLUSION

These data suggest that a metabolic alteration of IV-C may occur in ALS patients and decreased levels of urinary IV-C may be related to the decreased IV-C immunoreactivity of skin in ALS.

Urinary excretion of type IV collagen and laminin in the evaluation of nephropathy in NIDDM: comparison with urinary albumin and markers of tubular dysfunction and/or damage

To clarify the diagnostic relevance of urinary type IV collagen (IV-C) and laminin in diabetic nephropathy, the excretion of these basement membrane proteins were determined by enzyme immunoassay in 172 non-insulin-dependent diabetic patients with different grades of nephropathy and 64 non-diabetic control subjects, and were evaluated in comparison with those of urinary albumin, N-acetyl-beta-D-glucosaminidase (NAG) and alpha 1-microglobulin (alpha 1MG). These excretions were also compared between a group of non-diabetic renal disease (NDRD) patients (n = 24) and a subgroup of the diabetic patients studied (n = 76), whose urinary albumin excretion (UAE) varied within the ranges of micro- and macroalbuminuria. Of the diabetic patients studied, 49.7%, 53.4% and 32.4% had raised urinary albumin, NAG and alpha 1 MG excretion, respectively. In these patients, 54% and 53% exceeded the upper limit of normal for urinary IV-C and laminin. The level of IV-C and laminin excretion and the prevalence of their abnormal excretion showed a trend to increase with increasing grade of nephropathy, as assessed by UAE. In the normoalbuminuric [UAE < 20 mg/g creatinine (Cr)] stage, 28.3% and 26.3% patients had raised urinary IV-C and laminin excretion, respectively. In this stage, the excretion values for IV-C and laminin also rose significantly even when the UAE was < or = 10 mg/g Cr (P < 0.05 and P < 0.005, respectively). There was a close linear relationship between IV-C and laminin excretion (r = 0.73, P < 0.0001), together with their significant relationships with albumin, NAG and alpha 1MG excretion. The relationship of urinary IV-C and laminin with urinary NAG and alpha 1MG excretion remained significant even in normoalbuminuric patients. The normoalbuminuric patients with raised NAG and/or alpha 1MG excretion also had a higher prevalence of raised IV-C and laminin excretion than those with normal NAG and alpha 1MG excretion. The excretion values for IV-C and laminin, and the excretion ratios for IV-C/albumin and laminin/albumin were significantly higher in diabetic patients with evidence of incipient and clinical nephropathy than in NDRD patients, though the two patient groups had a comparable level of serum Cr and UAE. We conclude that the measurement of urinary IV-C and laminin may have potential for the evaluation of diabetic nephropathy. Furthermore, their determination might be helpful for distinguishing diabetic versus non-diabetic etiologies of altered renal function in diabetic patients.