Extravasation of brentuximab vedotin, an antibody-drug conjugate, in a patient with anaplastic large cell lymphoma

Brentuximab vedotin (BV) is an antibody-drug conjugate, consisting of a CD30-directed antibody, conjugated by a protease-cleavable linker to a microtubule disrupting agent auristatin E (MMAE). Although the safety datasheet of BV does not warn of severe toxic effects of extravasation, we report a third case of a patient with anaplastic large cell lymphoma who developed severe epidermal necrosis after extravasation. The reason for what happened could be attributed to the fact that MMAE belongs to the group of vinca alkaloids so it should be handled like other tissue-necrotising chemotherapeutics. Reporting of all cases of extravasation involving new conjugated chemotherapeutic drugs is of the utmost importance to be able to develop updated guidelines. Hospital pharmacists can provide information on how to manage extravasation, assess the potential risk, and have a crucial role in drafting hospital protocols.

Tracking flowpaths in a complex karst system through tracer test and hydrogeochemical monitoring: Implications for groundwater protection (Gran Sasso, Italy)

Groundwater in karst aquifers is frequently tapped for drinking purposes, due to frequent huge volumes of resources. Unfortunately, vulnerability of these aquifers can be high, due to possible fast transfer of recharge water on springs by the karst network. On Gran Sasso Mountain regional aquifer, several springs are subjected to drinking withdrawal and an updated evaluation of their potential is now a fundamental issue to be considered, facing climate change effects, which reflect on variation of discharge regimen and values. To distinguish between different contribution of spring recharge, a tracer test has been carried out on the Vitella d'Oro spring, fed both by the regional aquifer and by a local system exposed to karst features developed in the Rigopiano Conglomerates formation. Thanks to hydrogeological, hydrogeochemical and isotopic data, a conceptual model of spring recharge has been proposed and subsequently validated by the tracer test results. All information confirms the superimposition on the regional base flow, by a relevant contribution of the karst network, influencing the spring discharge in recharge periods. In detail, a fast flow component is responsible for discharge peaks and frequently of turbidity events, having a mean velocity ranging from 30 to 70 m/h in the aquifer. Besides of this fast flow, an additional aliquot of the recharge is due to the same local aquifer, but slower flow clearly identifiable by hydrochemistry and isotopic data. Thanks to these findings, a renewed management of the spring has been suggested, considering the different degrees of aquifer vulnerability (turbidity occurrence) directly related to the discharge regimen.

Groundwater flow velocities in a fractured carbonate aquifer-type: Implications for contaminant transport

Contaminants that are highly soluble in groundwater are rapidly transported via fractures in mechanically resistant sedimentary rock aquifers. Hence, a rigorous methodology is needed to estimate groundwater flow velocities in such fractured aquifers. Here, we propose an approach using borehole hydraulic testing to compute flow velocities in an un-faulted area of a fractured carbonate aquifer by applying the cubic law to a parallel plate model. The Cadeby Formation (Yorkshire, NE England) - a Permian dolostone aquifer present beneath the University of Leeds Farm - is the fractured aquifer selected for this hydraulic experiment. The bedding plane fractures of this dolostone aquifer, which are sub-horizontal, sub-parallel and laterally persistent, largely dominate the flow at shallow (<~40 mBGL) depths. These flowing bedding plane discontinuities are separated by a rock matrix which is relatively impermeable (K_well-test/K_core-plug~10⁴) as is common in fractured carbonate aquifers. In the workflow reported here, the number of flowing fractures - mainly bedding plane fractures - intersecting three open monitoring wells are found from temperature/fluid conductivity and acoustic/optical televiewer logging. Following well installation, average fracture hydraulic apertures for screened intervals are found from analysis of slug tests. For the case study aquifer, this workflow predicts hydraulic apertures ranging from 0.10 up to 0.54 mm. However, groundwater flow velocities range within two order of magnitude from 13 up to 242 m/day. Notably, fracture apertures and flow velocities rapidly reduce with increasing depth below the water table; the upper ~10 m shows relatively high values of hydraulic conductivity (0.30-2.85 m/day) and corresponding flow velocity (33-242 m/day). Permeability development around the water table in carbonate aquifer-types is common, and arises where high pCO₂ recharge water from the soil zone causes calcite/dolomite dissolution. Hence, agricultural contaminants entering the aquifer with recharge water are laterally transported rapidly within this upper part. Computation of groundwater flow velocities allows determination of the Reynolds number. Values of up ~1, indicating the lower limit of the transition from laminar to turbulent flow, are found at the studied site, which is situated away from major fault traces. Hence, turbulent flow is likely to arise in proximity to tectonic structures, such as normal faults, which localize flow and enhance karstification. The occurrence of turbulent flow in correspondence of such tectonic structures should be represented in regional groundwater flow simulations.

MSC-Delivered Soluble TRAIL and Paclitaxel as Novel Combinatory Treatment for Pancreatic Adenocarcinoma

Pancreatic cancer is the fourth leading cause of cancer death in western countries with more than 100,000 new cases per year in Europe and a mortality rate higher than 90%. In this scenario, advanced therapies based on gene therapies are emerging, thanks to a better understanding of tumour architecture and cancer cell alterations. We have demonstrated the efficacy of an innovative approach for pancreatic cancer based on mesenchymal stromal cells (MSC) genetically engineered to produce TNF-related Apoptosis Inducing Ligand (TRAIL). Here we investigated the combination of this MSC-based approach with the administration of a paclitaxel (PTX)-based chemotherapy to improve the potential of the treatment, also accounting for a possible resistance onset.

Methods: Starting from the BXPC3 cell line, we generated and profiled a TRAIL-resistant model of pancreatic cancer, testing the impact of the combined treatment in vitro with specific cytotoxicity and metabolic assays. We then challenged the rationale in a subcutaneous mouse model of pancreatic cancer, assessing its effect on tumour size accounting stromal and parenchymal organization.

Results: PTX was able to restore pancreatic cancer sensitivity to MSC-delivered TRAIL by reverting its pro-survival gene expression profile. The two compounds cooperate both in vitro and in vivo and the combined treatment resulted in an improved cytotoxicity on tumour cells.

Conclusion: In summary, this study uncovers the potential of a combinatory approach between MSC-delivered TRAIL and PTX, supporting the combination of cell-based products and conventional chemotherapeutics as a tool to improve the efficacy of the treatments, also addressing possible mechanisms of resistance.

Characterizing flow pathways in a sandstone aquifer: Tectonic vs sedimentary heterogeneities

Sandstone aquifers are commonly assumed to represent porous media characterized by a permeable matrix. However, such aquifers may be heavy fractured when rock properties and timing of deformation favour brittle failure and crack opening. In many aquifer types, fractures associated with faults, bedding planes and stratabound joints represent preferential pathways for fluids and contaminants. In this paper, well test and outcrop-scale studies reveal how strongly lithified siliciclastic rocks may be entirely dominated by fracture flow at shallow depths (≤180m), similar to limestone and crystalline aquifers. However, sedimentary heterogeneities can primarily control fluid flow where fracture apertures are reduced by overburden pressures or mineral infills at greater depths. The Triassic St Bees Sandstone Formation (UK) of the East Irish Sea Basin represents an optimum example for study of the influence of both sedimentary and tectonic aquifer heterogeneities in a strongly lithified sandstone aquifer-type. This fluvial sedimentary succession accumulated in rapidly subsiding basins, which typically favours preservation of complete depositional cycles including fine grained layers (mudstone and silty sandstone) interbedded in sandstone fluvial channels. Additionally, vertical joints in the St Bees Sandstone Formation form a pervasive stratabound system whereby joints terminate at bedding discontinuities. Additionally, normal faults are present through the succession showing particular development of open-fractures. Here, the shallow aquifer (depth≤180m) was characterized using hydro-geophysics. Fluid temperature, conductivity and flow-velocity logs record inflows and outflows from normal faults, as well as from pervasive bed-parallel fractures. Quantitative flow logging analyses in boreholes that cut fault planes indicate that zones of fault-related open fractures characterize ~50% of water flow. The remaining flow component is dominated by bed-parallel fractures. However, such sub-horizontal fissures become the principal flow conduits in wells that penetrate the exterior parts of fault damage zones, as well as in non-faulted areas. The findings of this study have been compared with those of an earlier investigation of the deeper St Bees Sandstone aquifer (180 to 400m subsurface depth) undertaken as part of an investigation for a proposed nuclear waste repository. The deeper aquifer is characterized by significantly lower transmissivities. High overburden pressure and the presence of mineral infillings, have reduced the relative impact of tectonic heterogeneities on transmissivity here, thereby allowing matrix flow in the deeper part of the aquifer. The St Bees Sandstone aquifer contrasts the hydraulic behaviour of low-mechanically resistant sandstone rock-types. In fact, the UK Triassic Sandstone of the Cheshire Basin is low-mechanically resistant and flow is supported both by matrix and fracture. Additionally, faults in such weak-rocks are dominated by granulation seams representing flow-barriers which strongly compartmentalize the UK Triassic Sandstone in the Cheshire Basin.

Accuracy of eight-polar bioelectrical impedance analysis for the assessment of total and appendicular body composition in peritoneal dialysis patients

OBJECTIVE

To establish the accuracy of bioelectrical impedance analysis (BIA) for the assessment of total and appendicular body composition in peritoneal dialysis (PD) patients.

DESIGN

Cross-sectional study.

SETTING

University Nephrology Clinic.

SUBJECTS

In all, 20 PD patients and 77 healthy controls matched for gender, age and body mass index.

METHODS

Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by dual-energy X-ray absorptiometry. Resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz. Whole-body resistance was calculated as the sum of R of arms, trunk and legs. The resistance index (RI) was calculated as the ratio between squared height and whole-body or segmental R.

RESULTS

RI at 500 kHz was the best predictor of FFM, LTM(arm) and LTM(leg) in both PD patients and controls. Equations developed on controls overestimated FFM and LTM(arm) and underestimated LTM(leg) when applied to PD patients. Specific equations were thus developed for PD patients. Using these equations, the percent root mean-squared errors of the estimate for PD patients vs controls were 5 vs 6% for FFM, 8 vs 8% for LTM(arm) and 7 vs 8% for LTM(leg).

CONCLUSION

Eight-polar BIA offers accurate estimates of total and appendicular body composition in PD patients, provided that population-specific equations are used.

Accuracy of eight-polar bioelectrical impedance analysis for the assessment of total and appendicular body composition in peritoneal dialysis patients

OBJECTIVE

To establish the accuracy of bioelectrical impedance analysis (BIA) for the assessment of total and appendicular body composition in peritoneal dialysis (PD) patients.

DESIGN

Cross-sectional study.

SETTING

University Nephrology Clinic.

SUBJECTS

In all, 20 PD patients and 77 healthy controls matched for gender, age and body mass index.

METHODS

Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by dual-energy X-ray absorptiometry. Resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz. Whole-body resistance was calculated as the sum of R of arms, trunk and legs. The resistance index (RI) was calculated as the ratio between squared height and whole-body or segmental R.

RESULTS

RI at 500 kHz was the best predictor of FFM, LTM(arm) and LTM(leg) in both PD patients and controls. Equations developed on controls overestimated FFM and LTM(arm) and underestimated LTM(leg) when applied to PD patients. Specific equations were thus developed for PD patients. Using these equations, the percent root mean-squared errors of the estimate for PD patients vs controls were 5 vs 6% for FFM, 8 vs 8% for LTM(arm) and 7 vs 8% for LTM(leg).

CONCLUSION

Eight-polar BIA offers accurate estimates of total and appendicular body composition in PD patients, provided that population-specific equations are used.

Student contributions to clinical agencies: a comparison of adult health and psychiatric staff nurses' perceptions

Clinical rotations in acute medical and psychiatric inpatient facilities are an essential component of the education for undergraduate nursing students. The benefits students receive from these clinical experiences have been documented, but no data have been reported regarding the advantages that students may bring to agencies. This exploratory study, which used a mail-back survey, asked adult health/medical-surgical nurses and mental health/psychiatric nurses in acute care units about the effects undergraduate nursing students had on staff time, staff development, quality of care, staff's personal satisfaction, and unit standards and practices during their clinical rotations. Results indicated that students contribute to the personal and professional satisfaction of the staff by offering opportunities for mentoring and reciprocal learning and allowing nurses to participate in students' professional development. Students also contribute to patient care.

Anesthesia for endobronchial laser surgery: a modified technique

We describe a technique for endobronchial surgery with the neodynium:yttium-aluminum-garnet laser, in which an insufflation catheter with side holes placed into the contralateral mainstem bronchus is used for high-frequency positive pressure ventilation. Thirty-five patients (45 procedures) were treated during general anesthesia using a rigid bronchoscope in combination with a fiberoptic bronchoscope. Perioperatively, oxygen saturation (SaO2), mean arterial pressure, and heart rate were recorded. SaO2 during the recovery period was comparable to that during the intraoperative period but was significantly (P < 0.05) higher than that before the induction of anesthesia. There was a considerable (> or = 5%) increase in SaO2 at the end of the treatment in six patients, which indicates that the recanalization of the treated airway was successful. Our data support the assumption that, during endobronchial resection, selective ventilation of the nonaffected lung was adequate; in addition, subcarinal placement of the insufflation catheter with side holes was advantageous. We conclude that this technique contributes to the prevention of lung complications during endobronchial laser surgery.

IMPLICATIONS

We describe a technique in which an insufflation catheter with side holes placed into the contralateral mainstem bronchus largely prevented inhalation of laser smoke and aspiration of blood and debris.

[Quality assurance and control of dialysis access]

Preliminary experience on total quality program in access surgery for dialysis is described; this kind of "border-line" surgery requires peculiar standards, documents and quality indexes. The use of a quality index based on a minimum success rate of 90% in elective access surgery is proposed. In addition, a "cross-index", suitable for quality evaluation of different dialysis sectors at the same time, is expressed. First interventions aimed at the optimal use of resources are described.

Nature's motility blockers: controlling human sperm motility machinery from the outside. Chemical characterization of a peritoneal fluid lipid that induces sperm immobilization

A molecule isolated from the peritoneal fluids of women undergoing laparoscopy for in-vitro fertilization techniques has been chemically characterized and identified as 1-palmitic-3-phosphorylcholine (lysophosphatidylcholine, LPC). This lipid is able, at physiological concentrations, to completely inhibit sperm motility in vitro in a dose-dependent way. Synthetic LPC induced rapid and complete arrest of sperm motility when added to sperm suspensions at physiological concentrations without any damage to cell membranes. Taken together, these results suggest that LPC may represent a previously unrecognized in-vivo modulator of human sperm motility.

Natural history of nutrition in chronic renal failure

Dietetic manipulation significantly influences the progression of renal failure in laboratory animals. Clinical results in humans are contradictory. The aim of the study was epidemiological research on a large sample of kidney disease patients to verify whether renal failure influences nutrient intake before dietetic manipulation. Four hundred and forty-one consecutive, non-selected adult patients with renal insufficiency (creatinine 133-963 mumol, mean 301 +/- 178 mumol in male, 288 +/- 156 mumol/l in female) and 43 kidney disease patients without renal failure were enrolled in the prospective study in the period 1988-1995. Interview at the time of the first nephrological check was performed by only one dietician; the record by recall of intake over 7 days with quantitative assessment was collected with the assistance of nutritional dossier and photographic measures. The patients with renal failure consume energy, proteins, lipids and carbohydrates in lesser quantities than the national population of the same geographical area, but the total lipid and monounsaturated fatty acid intake is higher compared with Italian dietary reference values. In patients with renal failure mean protein intake was 1.02 +/- 0.2 g/kg/day in males and 0.96 +/- 0.2 g/kg/day in females; mean lipid intake was 1.10 +/- 0.2 g/kg/day in males and 1.17 +/- 0.3 g/kg/day in females; mean carbohydrate intake was 3.7 +/- 1.1 g/kg/day in males and 3.49 +/- 1 g/kg/day in females. The nutrition alterations observed in chronic renal failure may be a biological adaptation due to neurological changes affecting the sense of taste.

Haemodialysis therapy in the elderly

Haemodialysis therapy in the elderly has become a recognized reality only in the last decade Information collected from restricted statistics often leads to conflicting conclusions. Length of survival may be a useful indicator of the appropriateness of initiating treatment. Survival and important determinants of survival, such as cardiovascular problems, nutritional status and adequacy of dialysis, are addressed in this study and evaluated in 365 elderly patients, treated at a single institution over a 20 year period.

Cryoglobulinemia in HCVAb+ patients on chronic hemodialysis

OBJECTIVE

Striking evidence of HCV infection has been found in mixed cryoglobulinemia (MC) and HCV has been hypothesized to be the causative agent of this disease. To assess the association of C virus infection and cryoglobulinemia we studied cryoglobulin levels in 66 patients on maintenance hemodyalisis who were selected on the basis of HCVAb positivity and not because they were affected by liver disease. The control group was made up of 45 patients also on hemodyalisis but without HCV infection.

RESULTS

Circulating cryoglobulins were found in 34 (52%) of 66 HCV+ patients: the cryocrit was < 1% in 20, 1 to 5% in 12, and > 5% in 2 patients. The cryoglobulins were classified by immunofixation as type II in 8 and type III in 8 others; identification was not possible in 18 cases. In the HCVAb- control group untypable cryoglobulins were detected in 9% of the patients at < 1% by volume. No correlation was found between these data and the liver disease detected by biohumoral tests.

CONCLUSIONS

Our data confirm the close link between HCV infection and cryoglobulins; the prevalence of circulating cryoglobulins in uremic HCVAb+ patients is very close to that found in HCV-related liver disease.

Axillary plexus blockade in microvascular surgery, a steal phenomenon?

A case report is presented of an axillary plexus blockade following a second toe-to-hand transfer. After completion of the microvascular anastomoses and restoration of blood flow to the transplanted toe, the axillary plexus blockade was started. Together with the vasodilation of the hand and forearm there was a marked drop in blood flow in the transplanted toe. Possible explanations for this phenomenon are considered. We suggest starting axillary plexus blockade before completion of microvascular anastomoses and maintaining a continuous postoperative blockade.

Effect of peritoneal fluid supplemented with exogenous progesterone on sperm motility in vitro

Since progesterone has been claimed to induce acrosomal reaction and hyperactivated motility of human spermatozoa, the present study was undertaken to determine if its presence at concentrations similar to those of peri-ovulatory follicular fluid could influence the effect of peritoneal fluid on sperm motility in vitro. To this end, 11 sperm samples were incubated at 37 degrees C with five peritoneal fluids with/without exogenous progesterone, and sperm motility was assessed using a computer-assisted analyser at time (t) = 0, 2.5, 5 and 24 h. Overall there was no observable constant trend for enhancement or inhibition of sperm motility. Progesterone generally induced a negative effect on those sperm samples with high velocities in the native peritoneal fluids and a positive effect on those sperm samples demonstrating low motility in the native peritoneal fluids. The incorporation of progesterone into the incubation medium seemed to result in a 'tuning' of sperm velocity to around 30-50 micron/s. However, a given sperm sample reacted differently when incubated with various peritoneal fluids and, reciprocally, different semen samples incubated with the same peritoneal fluid showed very variable motility patterns. The greater variability of the effects exerted by progesterone on sperm motility could arise from the fact that each sperm sample may contain subpopulations of gametes with different sensitivity to progesterone.

Purification of a factor from human peritoneal fluid that is able to immobilize spermatozoa

Human peritoneal fluid has been claimed to influence sperm motility. This report gives evidence for the presence in midcycle peritoneal fluid of a protein-bound, lipidic (hydrophobic) component able to immobilize spermatozoa as a function of time. This component was extracted from molecular weight-sieving and ion-exchange/high pressure liquid chromatography (HPLC)-purified peritoneal fluid fractions by either chloroform/methanol or charcoal treatments; resuspension of the chloroform/methanol extract with BWW-buffer and subsequent testing on spermatozoa resulted in sperm immobilization. Sequential or step-down chromatographic procedures (molecular weight-sieving-->cation-exchange-->anion-exchange HPLC separations of native peritoneal fluid) and extensive dialysis against double distilled water allowed the purification of the sperm immobilizing factor, as evidenced by the shorter incubation times necessary for sperm immobilization. Furthermore, the active fraction was found to immobilize spermatozoa without affecting its viability. Separation of the chloroform/methanol extracted immobilizing fraction on thin layer chromatography under conditions for phospholipid detection allowed the identification of a characteristic band which, after re-extraction, was found to be the sperm immobilizing substance. This factor does not contain choline, ethanolamine or serine. These results suggest that some lipidic peritoneal fluid components may influence sperm motility.

Conjugated diene fatty acids in patients with chronic renal failure: evidence of increased lipid peroxidation?

Conjugated diene fatty acids (CDFA) were evaluated by second derivative spectrophotometry in the plasma and adipose tissue of 42 chronic renal failure (CFR) patients in conservative treatment, 40 patients treated by hemodialysis (HD) with cuprophane, cellulose acetate or hemophan, 29 treated by hemodiafiltration (HDF) with polysulfone, polyacrylonitrile or polyamide, and 28 healthy controls. Plasma CDFA were also evaluated at the beginning, at 30 min and at the end of the dialytic session. CDFA were unchanged in CRF patients with creatinine clearance (Ccr) > 10 ml/min respect to the controls, CRF patients with Ccr < 10 ml/min showed a higher level of CDFA both in plasma and adipose tissue (p < 0.02). HD patients showed values similar to those of the control group. The lowest level of CDFA was found in HDF patients (p < 0.01 for plasma, p < 0.05 for adipose tissue versus both control and any other group). A significant relationship between plasma and adipose tissue CDFA was found in all groups. In the group of CRF patients with Ccr < 10 ml/min, females exhibited a higher level of CDFA both in plasma and adipose tissue. No significant change was found during dialytic session, independently from the membrane used. CDFA are not only primary products of lipid peroxidation, but also have a dietary origin, primarily from dairy products. Taking into account the reduced dietary intake, the increase in end-stage CRF may be due to an enhanced oxidative stress and/or to abnormalities in CDFA metabolism. Uremic patients, particularly in the predialytic stage, should be considered at risk for increased oxidative stress. HDF treatment better corrects the abnormality compared to conventional HD.

Prevalence of hepatitis C virus (HCV) antibodies in haemodialysis patients

The prevalence of antibodies to HCV and the course of hepatitis have been determined in 357 haemodialysed patients treated at a single institution. The prevalence of HCV infection increases with the duration of haemodialysis and with the use of blood transfusions, yet there is high frequency of HCV seropositivity even without blood transfusions. Evolution of HCV hepatitis to chronicity is frequent and biological signs of chronic hepatopathy can coexist with absence of alanine aminotransferase (ALT) abnormalities.

Behavior of antibody profile against hepatitis C virus in patients on maintenance hemodialysis

The prevalence of anti-hepatitis C virus (HCV) in dialysis setting is still a nonstandard datum. In particular, it is not known of the phenomenon is stable or increasing or decreasing, even in a given geographical area. We studied the behavior of anti-HCV prevalence during a 12-month follow-up in 415 hemodialysis patients treated at a single institution and belonging to a limited geographical area with standard HCV endemic. Point prevalence of anti-HCV has shown a tendency to growth linked in part of the incidence of infection, in part to new positivities in patients already on dialysis treatment. More than 50% of the new HCV-positive patients, had no history of classical parenteral transmission of the virus. These findings suggest that HCV infection is a phenomenon on the increase in dialysis units and that dialysis treatment emerges as an independent risk factor in contracting infection.

Electrophoretical patterns of seminal plasma proteins in patients with cystic fibrosis

Seminal plasma (n = 12) from cystic fibrosis (CF) patients were analyzed by gel-electrophoresis using seminal plasma and expressed prostatic secretion from fertile men as controls. Heavy precipitation at the entering position of the gel and streaking in the gel matrix was observed, demonstrating a reduced solubility of seminal proteins in CF. Comparison of the protein patterns evidenced that CF-seminal plasma (CF-SP) mainly consisted of prostatic components. Although lactoferrin was undetectable in all samples, trace amounts of low molecular weight proteins were observed in two patients. This latter finding could imply that CF-SP may contain proteolytic fragments of prostatic and/or vesicular proteins or de novo synthesized components.

Determinants of bile secretion: effect of bile salt structure on bile flow and biliary cation secretion

The effect of five bile salts, deoxycholate, chenodeoxycholate, cholate, ursodeoxycholate, and ursocholate, possessing (in decreasing order) different hydrophobicity, on bile flow and biliary secretion of total calcium, magnesium, sodium, and potassium was studied in 10 patients with T-tubes. Each subject was infused intraduodenally with one or two bile salts, given separately, to produce a selective enrichment of biliary bile salts with the infused bile salt. The choleresis induced per 1-mumol increase of bile salt output was greater during the secretion of 7 beta-hydroxylated bile salts, ursodeoxycholate (0.029 ml), and ursocholate (0.027 ml), followed in decreasing order by deoxycholate (0.023 ml), chenodeoxycholate (0.019 ml), and cholate (0.009 ml). Deoxycholate stimulated the greatest increase in cation secretion per unit increase in bile salt output, followed by chenodeoxycholate and cholate. The two 7 beta-hydroxylated bile salts induced greater cation secretion than did their 7 alpha-epimers. Whereas biliary concentration of divalent cations differed depending on the structure and concentration of the infused bile salt, the concentration of monovalent cations was constant for any species and concentration of infused bile salt. Relationships between bile salt and divalent cation concentration indicate that 1 mumol of secreted biliary deoxycholate, the most hydrophobic bile salt, associates with the greatest amount of calcium (0.046 mumol) and magnesium (0.022 mumol), followed by chenodeoxycholate (0.020 and 0.010 mumol, respectively) and cholate (0.012 and 0.008 mumol, respectively). The capacity of ursodeoxycholate and ursocholate to associate with calcium and magnesium seems to be less than that of their 7 alpha-epimers. These data suggest that of the common bile salts, the more hydrophobic bile salts stimulate bile flow and cation secretion better than the more hydrophilic bile salts, whereas ursodeoxycholate and ursocholate are more effective than their more hydrophobic 7 alpha-epimers. Whereas different bile salts seem to influence the secretion of sodium and potassium mainly by virtue of their choleretic properties, the effect of bile salt structure on biliary secretion of calcium and magnesium suggests the presence of a secretory link that might be consistent with cation-bile salt binding.

Effect of ursocholic acid on bile lipid secretion and composition

To further clarify the relationship between physical-chemical characteristics of bile acids and biliary lipid secretion, we investigated the effect of ursocholic acid, the 7 beta-hydroxyepimer of cholic acid, on bile lipid secretion and composition. The study included acute duodenal infusion (1 g/h for 5 h) of ursocholic acid contrasted with a less hydrophilic bile acid, ursodeoxycholic acid, in 3 T-tube patients and short-term oral administration (2 wk) of ursocholic acid (10-15 mg/kg X day) to 10 gallstone patients. Following acute infusion, ursocholic acid, similarly to ursodeoxycholic acid, accounted for greater than 80% of the biliary bile acids. However, ursocholic acid induced (per micromole of secreted bile acid) a significantly lower (p less than 0.01) secretion of cholesterol (0.013 mumol) and phospholipids (0.054 mumol) than that induced by ursodeoxycholic acid (0.034 mumol of cholesterol and 0.138 mumol of phospholipids). Biliary alkaline phosphatase activity during ursocholic acid administration was significantly lower (p less than 0.01) than during ursodeoxycholic acid administration. After short-term oral administration, ursocholic acid, undetectable before treatment, constituted 20.50% +/- 8.60% of the biliary bile acids. The percentage of deoxycholic acid increased from 32.35% +/- 18.79% to 47.53% +/- 16.19% (p less than 0.05). Mean saturation index decreased from a pretreatment value of 1.23 +/- 0.22 to 0.99 +/- 0.17 (p less than 0.05), but only in 4 of 10 subjects did bile become undersaturated. It is concluded that ursocholic acid, due to its higher hydrophilicity, stimulates a lower cholesterol and phospholipid output than ursodeoxycholic acid. Consequently, despite the low enrichment of the biliary bile acids with ursocholic acid, oral administration of ursocholic acid induces a reduction of bile cholesterol saturation.

Effects of acute changes of bile acid pool composition on biliary lipid secretion

To elucidate the mechanism responsible for the bile acid-induced changes of biliary lipid secretion, we evaluated bile flow and biliary output of bile acids, cholesterol, phospholipids, and alkaline phosphatase activity in seven cholecystectomized subjects with a balloon occludable T-tube during two experimental periods: (a) depletion of the endogenous bile acid pool and (b) replacement of the pool by means of duodenal infusion with individual bile acids, such as deoxycholic (DCA), chenodeoxycholic (CDCA), cholic (CA), and ursodeoxycholic (UDCA) acids. Bile flow, cholesterol, and phospholipid output were linearly related to bile acid secretion in all experimental periods. During the replacement periods, the amount of cholesterol and phospholipids coupled to bile acids was significantly different (at 1% level at least) for each individual bile acid secreted; it was the highest during DCA secretion (slope value: 0.209 for cholesterol and 0.434 for phospholipids) followed, in the order, by CDCA (0.078 and 1.794), CA (0.044 and 0.127), and UDCA (0.030 and 0.122). The phospholipid to cholesterol ratio was higher during secretion of CA and UDCA as compared with DCA and CDCA. The secretion of CA seemed to stimulate a greater bile flow than the other bile acids did. The infusion of all bile acids, except UDCA, induced an increase of biliary alkaline phosphatase activity as compared with the values of the depletion period. The mean highest increase (13-fold the pretreatment value) was observed during DCA secretion followed by CDCA (fivefold) and CA (1.5-fold). These results would suggest that the physical chemical properties, namely the lipid-solubilizing capacity, of bile acids could directly contribute to the regulation of biliary lipid secretion. The observed changes in biliary alkaline phosphatase activity lend support to the view that bile acid-induced lipid secretion may be, at least in part, contributed by membrane solubilization.