Effect of implementation interventions on nurses' behaviour in clinical practice: a systematic review, meta-analysis and meta-regression protocol

BACKGROUND

Practitioner-level implementation interventions such as audit and feedback, communities of practice, and local opinion leaders have shown potential to change nurses' behaviour in clinical practice and improve patients' health. However, their effectiveness remains unclear. Moreover, we have a paucity of data regarding the use of theory in implementation studies with nurses, the causal processes-i.e. mechanisms of action-targeted by interventions to change nurses' behaviour in clinical practice, and the constituent components-i.e. behaviour change techniques-included in interventions. Thus, our objectives are threefold: (1) to examine the effectiveness of practitioner-level implementation interventions in changing nurses' behaviour in clinical practice; (2) to identify, in included studies, the type and degree of theory use, the mechanisms of action targeted by interventions and the behaviour change techniques constituting interventions and (3) to examine whether intervention effectiveness is associated with the use of theory or with specific mechanisms of action and behaviour change techniques.

METHODS

We will conduct a systematic review based on the Cochrane Effective Practice and Organization of Care (EPOC) Group guidelines. We will search six databases (CINAHL, EMBASE, ERIC, PsycINFO, PubMed and Web of Science) with no time limitation for experimental and quasi-experimental studies that evaluated practitioner-level implementation interventions aiming to change nurses' behaviour in clinical practice. We will also hand-search reference lists of included studies. We will perform screening, full-text review, risk of bias assessment, and data extraction independently with the Covidence systematic review software. We will assess the quality of evidence using the GRADEpro software. We will code included studies independently for theory use (Theory Coding Scheme), mechanisms of action (coding guidelines from Michie) and behaviour change techniques (Behaviour Change Technique Taxonomy v1) with QSR International's NVivo qualitative data analysis software. Meta-analyses will be performed using the Review Manager (RevMan) software. Meta-regression analyses will be performed with IBM SPSS Statistics software.

DISCUSSION

This review will inform knowledge users and researchers interested in designing, developing and evaluating implementation interventions to support nurses' behaviour change in clinical practice. Results will provide key insights regarding which causal processes-i.e. mechanisms of action-should be targeted by these interventions, and which constituent components-i.e. behaviour change techniques-should be included in these interventions to increase their effectiveness.

SYSTEMATIC REVIEW REGISTRATION

The protocol has been registered at the International Prospective Register of Systematic Reviews (PROSPERO; registration number: CRD42019130446).

Who Shot the Cannonballs? Extensive Lung Metastases in a 39 Year Old Man

CASE

A 39 year-old man presented to the emergency department complaining of a cough of 2 months in duration. He also complained of weight loss of 20 pounds in two months and night sweats over the same period. An x-ray of the chest was performed and revealed innumerable lung nodules and masses. Computed tomography of the chest and abdomen were subsequently performed which confirmed the masses, but imaging did not reveal an obvious primary source. A testicular exam was performed but no obvious abnormalities were noted. Because of his age as well as the appearance of the lesions, a testicular ultrasound was then performed. The ultrasound found evidence of a 1.5 cm hypoechoic mass on the right testicle with dystrophic calcification in the interpolar region. Urology performed a right radical inguinal orchiectomy. Pathology demonstrated a malignant mixed germ cell tumor with seminoma and yolk sac components being prominent. He underwent four cycles of etoposide, ifosfamide, and cisplatin. His last positron emission tomography scan did not demonstrate active disease.

DISCUSSION

Each year about 8700 men are diagnosed with testicular cancer. 75 percent of these occur between the ages of 20 to 44, and the median age of diagnosis is 33. Testicular cancer should be suspected when a young male presents with metastatic disease such as in this case. In this patient, the genital exam was normal due to the small size of the testicular mass, but he had significant metastatic lesions. When cannonball metastases are seen on imaging, germ cell tumors and renal cell carcinoma should be high in the differential diagnosis.

LIFAC ash--strategies for management

LIFAC is a more recent addition to flue gas desulphurization methods for reducing sulphur emissions during coal combustion for the production of electricity. Ashes from the combustion of a low-sulphur lignite coal using LIFAC technology were used to evaluate different ash management strategies. The ashes, as produced and after treatment by the CERCHAR hydration process, were examined for their disposal characteristics and their utilization potential in concrete. They were also evaluated as underground disposal material using the AWDS process.

Advanced ash management technologies for CFBC ash

The combustion of high-sulphur coal demands the reduction of sulphur emissions. The sorbent most often used in sulphur capture technology is calcium-based. Ashes from technologies such as circulating fluidized bed combustion (CFBC), therefore, contain high calcium levels. The use and disposal of these ashes poses challenges, because of highly exothermic reactions with water, high-pH leachates, and excessive expansion of solidified materials. This paper looks at the potential of two post-combustion ash treatment processes, CERCHAR hydration and AWDS disposal, in solving these challenges. A high-sulphur coal-derived CFBC ash is examined, after CERCHAR hydration treatment, in conjunction with a conventionally hydrated ash, in a range of chemical, geotechnical and utilization scenarios. The ashes are used to make no-cement and roller-compacted concrete as well as Ash Water Dense Suspensions (AWDS). The solidified mortar paste from no-cement concrete is subjected to an extensive geochemical examination to determine how solidification progresses and strength develops, from a chemical point of view.

Nutritional status: a continuous quality improvement approach

Intradialytic parenteral nutrition (IDPN) has been used as nutritional repletion in severely malnourished patients with end-stage renal disease (ESRD). This study presents a retrospective look at hemodialysis patients with malnutrition who were followed-up in the process of continuous quality improvement (CQI). The costs of intravenous supplies, hospitalizations, and morbidity are reviewed. The application of continuous quality improvement was used to identify and follow-up malnourished patients. There were significant decreases in number of hospitalizations and days in the hospital.

Improving clinical processes: one dialysis facility's experiences

Northeast Louisiana Dialysis Center implemented continuous quality improvement (CQI) to improve the quality of care delivered to end stage renal disease (ESRD) patients treated by hemodialysis in their facility. The unit chose to address normalization of calcium and phosphorus and parathyroid hormone (PTH), anemia, nutrition, adequacy of dialysis and dialyzer reuse as well as performance benchmarks by the Health Care Financing Administration (HCFA) core indicators. This article presents the results obtained and the methodology used in this improvement effort. The article also presents nine principles the authors believe necessary for a successful CQI program.

The Quality Cup winner: Fletcher Allen Health Care's early extubation team

Many organizations are looking for ways to reduce the cost and improve the quality of open-heart surgery. Fletcher Allen Health Care in Burlington, Vermont used a total quality management approach to do just that. The result was a dramatic improvement in outcomes. Fletcher Allen won the 1994 USA Today Quality Cup for its efforts.

Use of the spiral vein graft as an arterial substitute for secondary access

A 30-year-old black male with end-stage renal disease of 8 years' duration had undergone 16 prior access operations and was still without an adequate access for dialysis. A spiral saphenous vein graft conduit was constructed from the left saphenous vein and used as a straight arterial conduit graft between the superficial femoral artery at Hunter's canal and the saphenofemoral vein junction in the groin. The spiral vein graft tube was used as the sole means of dialysis for the next consecutive 750 dialysis procedures over nearly 6 years without any complication.

Superiority of the internal jugular over the subclavian access for temporary dialysis

We studied angiographically the access route 1-27 months after the insertion temporary dialysis catheters in 52 patients: 32 subclavian and 20 internal jugular. The two groups were statistically similar with respect to age, sex and race. The subclavian catheters were left in for a mean of 11.5 days (2-22) while the internal jugular ones were inserted for 15.8 days (5-25; p = 0.0015). One hundred percent of the internal jugular patients were free of any venogram abnormalities in their venous access return. In marked contrast, 50% of the subclavian sites had mild to severe stricutures with 90% having 70-100% occlusion of the subclavian vein. Six patients had bilateral severe strictures. The long-term stricture rate of subclavian catheters in the subclavian vein was unacceptably high compared to the internal jugular route.

Enantiomers of 7-(2,3-epoxypropoxy)actinomycin D as dual-action DNA-acting antitumor agents

Enantiomeric forms of (+/-)-EPA [racemic 7-(2,3-epoxypropoxy)actinomycin D] have been synthesized; these are (R)-(+)- and (S)-(-)-EPA, which are active against a range of actinomycin resistant and marginally responsive tumors. The R-(+) enantiomer is uniformly superior to the other forms in all the tumor lines tested. These enantiomers act by binding to DNA, both by intercalation and alkylation at the guanine base of DNA. They are superior to actinomycin D in their in vitro activity against mouse leukemias (L1210 and P388/ADR) and mouse melanoma B16. This superior activity is also evident against all the preceding mouse leukemias and against solid tumors B16 and C26 in vivo. In biochemical action, the enantiomers behave similarly and act primarily by inhibiting DNA synthesis in tumor cells; the only difference found was in their preference for sites in DNA bases during alkylation. The R-(+) enantiomer generates an adduct that is believed to be bonded to the N7-site of guanosine; conversely, the S-(-) isomer forms two adducts with DNA that are different from the preceding one by HPLC and are tentatively assigned O6-guanosine-substituted structures on the basis of their UV, CD, and other chemical behaviors.

Measures of leucine aminopeptidase can be used to anticipate UV-induced age-related damage to lens proteins: ascorbate can delay this damage

This paper focuses on damage to soluble lens proteins during ultraviolet (UV) light exposure and its prevention by ascorbate (Vitamin C). Using 2.3 X 10(-3) W/cm2 UV A and 0.4 X 10(-4) W/cm2 UV B, aminopeptidase inactivation in lens supernatants is significant after 60 min. Protein aggregation and decreases in tryptophan levels, phenomena associated with UV-induced and cataract-related damage, are observed only after longer (6 h) UV exposure. Thus, it would appear that measurements of aminopeptidase activity can be used to anticipate damage to lens structural proteins. Ascorbate (15 mM) added to soluble lens proteins prior to photoirradiation can prevent some of these changes. The data presented suggest plausible relationships between impaired proteolysis and cataract formation.

Axillary artery to iliac vein vascular access using an externally supported prosthetic graft. A new procedure for the recalcitrant secondary access patient

The axillary artery-iliac vein graft using externally supported PTFE is a viable option for this difficult patient group. It is capable of functioning well for up to 12 months. Most importantly, despite numerous prior access procedures, the axillary artery and iliac vein in each case were amenable to the procedure. Critical technical points include the use of externally splinted PTFE grafts, avoidance of crossing joints, and angling of the graft in the direction of the iliac vein at that anastomosis. The lack of thrombosis or infection to date, coupled with successful dialysis in every patient, suggests that this is one more option that can be used in the difficult secondary access patient.

The eye lens has an active ubiquitin-protein conjugation system

Using exogenous 125I-ubiquitin, ubiquitin-lens protein conjugation was observed with supernatants of cultured rabbit lens epithelial cells and lens cortex tissue. Conjugation was ATP-dependent with the greatest variety and amount of conjugates larger than 150 kDa. In vivo production of ubiquitin-protein conjugates in cultured rabbit and beef lens epithelial cells and rabbit lens tissues of different developmental age was established using immunological detection. There were limited similarities between conjugates found in youngest as opposed to oldest tissue. Cultured rabbit cells contained 27 pmol/mg free ubiquitin and 18 pmol/mg conjugated ubiquitin. Levels of free ubiquitin in lens tissue epithelium, cortex, and core were 36, 5, and 5 pmol/mg, respectively. There were only 2 pmol/mg conjugated ubiquitin in each of these tissues. Hydrolysis of 125I-ubiquitin was catalyzed by supernatants of cultured lens cells, beef and human lens tissues, and reticulocytes. Degradation was greatest in epithelial tissues, and least in core. This corroborates studies which show that proteolytic capabilities are attenuated in older tissue. Decreased initiation of proteolysis by ubiquitination as well as diminished proteolysis in older lens tissue may be related to the accumulation of damaged proteins in aging lens tissue.

Delay of UV-induced eye lens protein damage in guinea pigs by dietary ascorbate

Large accumulations of postsynthetically oxidized proteins are observed in the aged and cataractous eye lens. Ascorbate has previously been used to delay photooxidative damage in vitro. The goals of this study were to confirm that dietary ascorbate can be used to enhance lens ascorbate levels and to determine if lenses with enhanced ascorbate can better withstand photooxidative stress in the form of ultraviolet (UV) light exposure. Guinea pigs were placed on high dietary ascorbate (HDA), 50 mg/day, and low dietary ascorbate (LDA), 2 mg/day, for 21 weeks. Lenses from HDA animals were found to contain 3.3 times more ascorbate than LDA animals. Prior to irradiation, SDS-PAGE protein profiles and exopeptidase activity in HDA and LDA lens soluble proteins were indistinguishable. However upon exposure to UV light, more protein damage (e.g., high-molecular-weight aggregates and enhanced loss of exopeptidase activity) was seen in lens preparations from LDA as compared to HDA animals. These results suggest that ascorbate protects lens components against cataract-like and age-related postsynthetic changes in vivo. As in previous tests on lens preparations, attenuated exopeptidase activity was observed before protein aggregation.

Covalent binding of isomeric 7-(2,3-epoxypropoxy)actinomycin D to DNA

We have examined the ability of 7-(2,3-epoxypropoxy)actinomycin D (EPA) to bind covalently to DNA and to 2'-deoxyribonucleoside 5'-monophosphates in a simple system in vitro. We have observed initially that EPA binds to DNA and deoxymono- and deoxydinucleotides with intercalative or stacking interactions that are characteristic of actinomycin D (AMD). When EPA is incubated (37 degrees C) for a prolonged period (pH 7.4, 6 h) in contact with either DNA or deoxyribonucleotides, it forms covalent adducts. Deoxyguanosine is always the preferred site of reaction by EPA. After enzymatic digestion of EPA-DNA adduct, three deoxyguanosine (EPA-dG) adducts, one major and two minor, were isolated. These adducts are separable from one another and from other deoxyribonucleoside adducts, e.g., EPA-dA and EPA-dC by reverse-phase HPLC. The authentic EPA-dG, EPA-dA, and EPA-dC adducts were synthesized by a chemical reaction of the epoxide in EPA with the deoxyribonucleotides followed by enzymatic dephosphorylation of the products. From the EPA-DNA adduct the EPA-dG adducts accounted for congruent to 2.2% of EPA employed; the remainder of EPA was completely hydrolyzed to an epoxide ring opened diol derivative, DHPA. DHPA binds to DNA by intercalation only and it does not form covalent adducts. Another model analogue of EPA (EPAMDEA) has the same epoxide-substituted chromophore but lacks the peptide lactone functions; it fails to associate with DNA and consequently it shows no covalent binding of its epoxide with DNA. Formation of a noncovalent intercalation complex between EPA and DNA appears to be a prerequisite for the covalent reaction. Presumably because of these dual interactions, EPA demonstrates superior antitumor activities both in human leukemic cells (CCRF-CEM) in vitro and P388 and L1210 cells in mice. The DNA base specific alkylating activity of EPA, which is derived from a combination of the actinomycin D (AMD) structure and the new epoxide function in the molecule of EPA, attributes to EPA a potentially novel pharmacological behavior that is not inherent of AMD.

Tetracyclic chromophoric analogues of actinomycin D: synthesis, structure elucidation and interconvertibility from one form to another, antitumor activity, and structure-activity relationships

Two different tetracyclic chromophoric analogues of actinomycin D have been synthesized by engaging two chromophoric DNA-binding functions in actinomycin D, i.e., 2-amino and 3-oxo, into either a 1,4-oxazin-2-one or an oxazole ring system. A third analogue has an extra quinone function at C-8 of the oxazole analogue. In all the analogues the chemical integrity of the peptide lactones of the parent antibiotic is kept intact, but their sterochemistry is altered. The analogues are designed as transport-modified prodrug forms of either the tricyclic active analogues of actinomycin D or actinomycin D itself. All analogues exhibit cytotoxicity that is several-fold less potent than AMD; they also have no binding affinity toward extracellular DNA. Nonetheless, the analogues of the first and the third series show improved antitumor activities (P388 leukemia, CDF1 mice). In fact, two of these analogues having a phenyl substituent at the C-3 site of the oxazinone ring or the C-2 position of the 8-oxo-8H-oxazole ring exhibit the highest antitumor effects. Most of the analogues are active over a broader dose range than actinomycin D and are 6- to 16-fold less cytotoxic to human lymphoblastic leukemia (CCFR-CEM) cells in vitro. The analogues with the most pronounced antitumor activity are those that retain most elements in the peptide stereochemistry of actinomycin D and have a quinone function or demonstrate susceptibility of their chromophores to biotransformation.

A gelatin-specific protease from hamster lung-derived cell cultures

Gelatin-specific protease activity from hamster lung fibroblasts and their culture media is described. The fibroblasts were derived from hamster lung explant cultures. The gelatin-specific protease activity is latent and seen only after dialysis of either cells or media. The enzyme activity shares many properties of previously reported gelatinases. The activity is inhibited by EDTA, cysteine, and dithioerythritol, whereas it is not inhibited by p-chloromecuribenzoate, N-ethyl maleimide, or phenylmethylsulfonyl fluoride. Of all substrates tested, activity was observed only against gelatin and not against other substrates tested. It was inactive toward collagen, elastin, and methemoglobin. This enzyme may have a role in the digestion of collagen that has been previously cleaved by mammalian collagenase.

Partial purification and characterization of a gelatin-specific protease from the culture media of human pulmonary alveolar macrophages

A gelatin-specific protease from the culture media of human pulmonary alveolar macrophages has been partial purified by gel filtration and characterized. The macrophages were obtained by bronchopulmonary lavage from the lungs of disease-free smoking volunteers. The gelatin-specific protease initially requires trypsin activation. After chromatographing the culture media on a Sephadex G-200 column, trypsin is no longer required for activation. The gelatin-specific protease reported here shares many properties of previously reported gelatinases. It is inhibited by EDTA, cysteine, dithiothreitol and serum. It is unaffected by other protease inhibitors: phenylmethylsulfonyl fluoride, tosyllysine chloromethyl ketone and p-chloromercuribenzoate. Of all substrates tested activity was observed only with gelatin. It was inactive toward collagen, elastin and methemoglobin. This enzyme may have a role in the digestion of collagen which has been cleaved by a mammalian collagenase.

Studies on the role of the liver and splanchnic tissues in the production of carbohydrate intolerance in uremia

The potential contribution of the splanchnic tissues to the carbohydrate intolerance of uremia was studied in fasted, partially nephrectomized rats. The livers of sham operated (C) and partially nephrectomized (Nx) rats were perfused with physiologic concentrations of potential gluconeogenic substrates using a nonrecirculating perfusion apparatus. Glucose release was slightly greater in the livers of Nx rats as compared to C rats. The portal vein concentrations of the potential gluconeogenic precursors were not different in the two groups. Moreover, there were no differences in the net hepatic extraction of alanine, glutamine or glutamate between the two groups of rats. There was also no difference in the production of glucose from U14C alanine. The livers of Nx rats, however, demonstrated less net extraction of lactate and released greater concentrations of betahydroxybutyrate. The increased release of glucose by livers of Nx rats may be at least partially due to their greater hepatic glycogen content.

Effect of intact parathyroid hormone on hepatic glucose release in the dog

The liver has been shown to remove parathyroid hormone (PTH) from its arterial circulation by a mechanism that is selective for the intact form of the peptide (PTH 1-84). The present studies demonstrate that PTH has biologic effects on the liver in vivo. Bovine PTH 1-84 stimulated hepatic glucose release in dogs with indwelling hepatic vein catheters from basal values of 31+/-8 to 68+/-9 mg/min per kg after bolus injections of PTH. The effect on hepatic glucose release was apparent by 5 min and persisted for the 80 min of observation. The NH(2)-terminal PTH fragment (syn b-PTH 1-34) had no effect. Bovine PTH 1-84 administered in doses designed to produce circulating levels of immunoreactive PTH similar to the endogenous levels observed in uremic dogs also increased the incorporation of (14)C from infused [(14)C]alanine into glucose, and increased estimated hepatic uptake of both chemical and [(14)C]alanine, while increasing hepatic glucose release. Thus, administration of "physiologic levels" of b-PTH 1-84 stimulated hepatic glucose release in part through increased gluconeogenesis in vivo, whereas syn b-PTH 1-34 had no demonstrable effect. Circulating levels of insulin rose after PTH administration, an increase which presumably represents a secondary response to the rise in glucose release. These results suggest that the liver is a target organ of PTH, and that PTH might potentially alter carbohydrate metabolism during hypersecretion. They also suggest that hepatic uptake of PTH may be related in part to production of a specific biologic effect rather than just simple peptide degradation.

Phosphate control and 25-hydroxycholecalciferol administration in preventing experimental renal osteodystrophy in the dog

Previous studies from this laboratory demonstrated that secondary hyperparathyroidism in dogs with chronic renal disease may occur, at least in part, as a consequence of the need for progressive adaptation in renal phosphorus (P) excretion that occurs as glomerular filtration rate falls. However, the studies were of relatively short duration. Moreover, no information emerged regarding a potential role of calcium malabsorption in the pathogenesis of secondary hyperparathyroidism. The short duration of the protocol did not lend itself to the study of the effect of P control or the administration of vitamin D in the pathogenesis of renal osteodystrophy. In the present studies, 14 dogs with experimental chronic renal disease were studied serially for a period of 2 yr. Each animal was studied first with two normal kidneys on an intake of P of 1,200 mg/day. Then, renal insufficiency was produced by 5/6 nephrectomy. The dogs then were divided into three groups. In group I, 1,200 mg/day P intake was administered for the full 2 yr. In group II, P intake was reduced from the initial 1,200 mg/day, in proportion to the measured fall in glomerular filtration rate, in an effort to obviate the renal adaptation in P excretion. In group III, "proportional reduction" of P intake also was employed; but in addition, 20 mug of 25(OH)D(3) were administered orally three times a week. In group I, parathyroid hormone (PTH) levels rose throughout the 2-yr period reaching a final concentration of 557+/-70 U (normal 10-60). In group II, values for PTH remained normal throughout the 1st yr, increased modestly between the 12th and the 18th mo, but then did not rise after the 18th mo. In group III, no elevation of PTH levels was observed at any time; however, these animals were hypercalcemic. Histomorphologic analyses of the ribs of these dogs were performed serially throughout the 2-yr period. A linear relationship was obtained between the osteoclastic resorption surface and the concentration of circulating immunoreactive PTH. The osteoid volume was greater in group I animals when compared to those in group II. None of the morphologic abnormalities associated with renal osteodystrophy were observed in the animals in the third group.

Chronic progressive renal disease: rate of change of serum creatinine concentration

The rate of change of the serum creatinine concentrations in 63 patients with chronic progressive renal disease of varied etiology was examined by linear regression analysis using the logarithm or the reciprocal of the serum creatinine concentration versus time. A single straight line was described by one or the other of these relationships in 53 patients. Six patients had an accelerated rate of nephron destruction terminally (two slopes) regardless of the mathematical analysis. The remaining four patients had course changes either due to apparent spontaneous remissions or temporally related to therapy. These data suggest that (functional) nephron loss in chronic progress disease is orderly and mathematically definable. The theoretical implications are that functional nephron loss is either exponential (log Cr) or constant (1/Cr).

The role of lysosomal elastase in the digestion of Escherichia coli proteins by human polymorphonuclear leukocytes: experiments with living leukocytes

Human polymorphonuclear leukocyte (PMN) elastase has been implicated in various pathological conditions. However, its physiological role remains undefined. One possible function of this enzyme may be digestion of bacterial proteins after phagocytosis. To test this hypothesis, we prepared Escherichia coli labeled with [3H]arginine and treated these bacteria with a lipid-soluble, active-site-directed chloromethyl ketone inactivator of pancreatic and granulocyte elastases (carbobenzoxy-L-glycyl-L-leucyl-L-alanine chloromethyl ketone, dissolved in methanol). Control bacteria were treated with methanol alone. When E. coli pretreated with the inactivator were incubated with solutions of porcine pancreatic elastase or with PMN granule extract, release of trichloroacetic acid-soluble radioactivity was significantly lower than in the control E. coli. Similar results were obtained when treated and control E. coli were fed to viable human PMN. In contrast, release of trichloroacetic acid-soluble radioactivity from E. coli containing [3H]thymidine was not affected by pretreatment of bacteria with elastase inactivator before feeding them to PMN, suggesting that phagocytosis of E. coli had not been inhibited by the chloromethyl ketone. When treated and control bacteria were fed to PMN, no significant difference was observed in the activity of lysosomal beta-glucuronidase recovered from post-granule supernatant fractions of homogenized leukocytes, suggesting that lysosomal degranulation had not been suppressed by the inactivator. However, elastase activity of the same fractions was depressed if the leukocytes had phagocytized chloromethyl ketone-treated E. coli, suggesting that inhibition of PMN elastase had occurred. We conclude that PMN elastase participates in digestion of E. coli proteins by human PMN.

Effect of 25-hydroxycholecalciferol on calcium absorption in chronic renal disease

Calcium absorption was measured in eight uremic patients before and after eight days of treatment with 100 or 500 mug of 25-hydroxycholecalciferol (25(OH)D3) per day. Fractional calcium absorption was estimated by administering 47Ca i.v. and orally on separate days and counting forearm radioactivity four hours later. Calcium absorption in four patients with residual renal function rose from 16.3 +/- 2.5 to 40.8 +/- 5.5% after treatment. In order to determine if the increased calcium absorption was mediated by an increase in the production of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) by virtue of increased substrate delivery to the 25-hydroxycholecalciferol-1-hydroxylase system present in the residual renal tissue, identical studies were performed in four anephric patients. Calcium absorption in these patients averaged 15.7 +/- 2.2% during the control period and rose to 46.0 +/- 11.1% after treatment. Increments in serum calcium after treatment were similar in both groups of patients; the mean concentration rose from 9.6 +/- 0.3 to 11.0 +/- 0.6 mg/100 ml. The results indicate that 25(OH)D3 can improve calcium absorption in the absence of renal tissue suggesting that its conversion to 1,25(OH)2D3 may not be necessary for its effect on the gastrointestinal tract in the uremic patient.

Renal function and metabolism after relief of unilateral ureteral obstruction

In summary, the present studies indicate the presence of both functional and structural abnormalities in the postobstructed kidney involving mitochondrial integrity and deranged intermediary metabolism. It is suggested that some of these metabolic changes may account in part for the functional abnormalities observed in vivo.