Clinical review: Biomarkers of acute kidney injury: where are we now?

The recognition that acute kidney injury (AKI) is a significant independent risk factor for morbidity and mortality has resulted in a substantial number of publications over the past 5 years or more. In no small part these have, to a degree, highlighted the inadequacy of conventional markers of renal insufficiency in the acute setting. Much effort has been invested in the identification of early, specific AKI markers in order to aid early diagnosis of AKI and hopefully improve outcome. The search for a 'biomarker' of AKI has seen early promise replaced by a degree of pessimism due to the lack of a clear candidate molecule and variability of results. We outline the major studies described to date as well as discuss potential reasons for the discrepancies observed and suggest that evolution of the field may result in success with ultimately an improvement in patient outcomes.     

Endoscopic Resection of the Peroneal Tubercle

Hypertrophy of the peroneal tubercle can be a source of discomfort when wearing shoes. Occasionally, it can cause tenosynovitis or a tear of the peroneal tendons. The symptoms can be successfully treated by complete resection of the tubercle, tenosynovectomy, and early range of motion exercises of the hindfoot joints. Traditionally, this is an open procedure. We report the technique of endoscopic resection of the peroneal tubercle.     

Phosphorylation of factor Va and factor VIIIa by activated platelets

Platelet activation leads to the incorporation of 32[PO4(2-)] into bovine coagulation factor Va and recombinant human factor VIII. In the presence of the soluble fraction from thrombin-activated platelets and (gamma-32P) adenosine triphosphate, radioactivity is incorporated exclusively into the M(r) = 94,000 heavy chain (H94) of factor Va and into the M(r) = 210,000 to 90,000 heavy chains as well into the M(r) = 80,000 light chain of factor VIII. Proteolysis of the purified phosphorylated M(r) = 94,000 factor Va heavy chain by activated protein C (APC) gave products of M(r) = 70,000, 24,000, and 20,000. Only the intermediate M(r) = 24,000 fragment contained radioactivity. Because the difference between the M(r) = 24,000 and M(r) = 20,000 fragments is located on the COOH-terminal end of the bovine heavy chain, phosphorylation of H94 must occur within the M(r) = 4,000 peptide derived from the carboxyl-terminal end of H94 (residues 663 through 713). Exposure of the radioactive factor VIII molecule to thrombin ultimately resulted in a nonradioactive light chain and an M(r) = 24,000 radioactive fragment that corresponds to the carboxyl-terminal segment of the A1 domain of factor VIII. Based on the known sequence of human factor VIII, phosphorylation of factor VIII by the platelet kinase probably occurs within the acidic regions 337 through 372 and 1649 through 1689 of the procofactor. These acidic regions are highly homologous to sequences known to be phosphorylated by casein kinase II. Results obtained using purified casein kinase II gave a maximum observed stoichiometry of 0.6 mol of 32[PO4(2-)]/mol of factor Va heavy chain and 0.35 mol of 32[PO4(2-)]/mol of factor VIII. Phosphoamino acid analysis of phosphorylated factor Va by casein kinase II or by the platelet kinase showed only the presence of phosphoserine while phosphoamino acid analysis of phosphorylated factor VIII by casein kinase II showed the presence of phosphothreonine as well as small amounts of phosphoserine. The platelet kinase responsible for the phosphorylation of the two cofactors was found to be inhibited by several synthetic protein kinase inhibitors. Finally, partially phosphorylated factor Va was found to be more sensitive to APC inactivation than its native counterpart. Our findings suggest that phosphorylation of factors Va and VIIIa by a platelet casein kinase II- like kinase may downregulate the activity of the two cofactors.     

Living well with kidney disease by patient and care-partner empowerment: Kidney health for everyone everywhere

Living with chronic kidney disease (CKD) is associated with hardships for patients and their care-partners. Empowering patients and their care-partners, including family members or friends involved in their care, may help minimize the burden and consequences of CKD related symptoms to enable life participation. There is a need to broaden the focus on living well with kidney disease and re-engagement in life, including an emphasis on patients being in control. The World Kidney Day (WKD) Joint Steering Committee has declared 2021 the year of “Living Well with Kidney Disease” in an effort to increase education and awareness on the important goal of patient empowerment and life participation. This calls for the development and implementation of validated patient-reported outcome measures to assess and address areas of life participation in routine care. It could be supported by regulatory agencies as a metric for quality care or to support labelling claims for medicines and devices. Funding agencies could establish targeted calls for research that address the priorities of patients. Patients with kidney disease and their care-partners should feel supported to live well through concerted efforts by kidney care communities including during pandemics. In the overall wellness programme for kidney disease patients, the need for prevention should be reiterated. Early detection with a prolonged course of wellness despite kidney disease, after effective secondary and tertiary prevention programmes, should be promoted. WKD 2021 continues to call for increased awareness of the importance of preventive measures throughout populations, professionals, and policy makers, applicable to both developed and developing countries.     

Factors controlling proliferation and progesterone production by bovine granulosa cells in serum-free medium

Bovine granulosa cells seeded in the presence of serum on extracellular matrix-coated dishes proliferate actively when exposed to serum-free medium supplemented with insulin (2 microgram/ml), fibroblast growth factor (FGF, 100 ng/ml), and high density lipoprotein (HDL, 30 microgram protein/ml). The final density of the cultures is 80-120% that of cultures grown in the presence of medium supplemented with optimal concentration (10%) of calf serum. Insulin has the greatest effect on cell proliferation when added alone to serum-free medium, since it induced an increase in cell number that was 35-60% that observed with optimal serum concentration. Somatomedin C can replace insulin when added alone. FGF, epidermal growth factor, or HDL had no significant effect on cell proliferation by themselves. When these factors were added together with insulin, they acted synergistically in stimulating cell proliferation. When cultures were seeded in the total absence of serum, the addition of transferrin (10 microgram/ml) to serum-free medium was required in order for insulin and FGF to be mitogenic. Cultures maintained on extracellular matrix and exposed to serum-free medium alone have a lifespan in culture of 4 generations. Addition of insulin, FGF, and HDL increases the lifespan of the cultures to 12 generations. Bovine granulosa cells, which proliferate in a defined medium, respond to dibutyryl cAMP by releasing progesterone into the medium. Addition of FSH to the defined medium resulted in a 30% decrease in cell proliferation and in a 2.1-fold increase in the amount of progesterone released into the medium in response to dibutyryl cAMP. This release of progesterone reached a level similar to that observed with cultures grown in medium supplemented with optimal concentration of serum and exposed or not to FSH during their growth phase and at confluence. These results demonstrate that bovine granulosa cells can actively proliferate in a serum-free medium and maintain their differentiated function, as indicated by their ability to produce progesterone.