Inflammatory response to titanium surfaces with fibrinogen and catalase coatings: Anin vitro study

The aim of the present study was to evaluate the possibility to modulate the early inflammatory response in vitro by coating titanium surfaces with candidate proinflammatory (fibrinogen coated turned titanium "Fib") and antiinflammatory proteins (catalase on top of fibrinogen coated turned titanium "Cat"). Additionally, turned titanium surfaces (Ti) were used as controls. The discs were incubated with human mononuclear cells. Adhered cells were investigated with respect to number, viability, differentiation (acute marker 27E10 vs. chronic marker RM3/1), and cytokine production (TNF-alpha and IL-10), after 24 and 72 h. The results indicated that it is possible to modulate the inflammatory response with protein coatings. However, the strongest inflammatory response, indicated by increased number of adhered cells and release of pro and antiinflammatory mediators, was induced by Cat. Furthermore, the cytokine production on this surface was not sensitive to LPS stimulation. Differentiation measured as the expression of the chronic cell surface marker, dominated after 72 h for all surface modifications and Cat displayed an increased number compared to the others. A decrease in the total number of adhered cells and amounts of TNF-alpha were observed on all surfaces over time. The cell viability was, in general, high for all tested surfaces. In conclusion, the study proved it possible to influence the early inflammatory response in vitro by immobilizing protein coatings to titanium surfaces. However, the catalase surface demonstrated the strongest inflammatory response, and the possibility to selectively use the potent antiinflammatory capacity of catalase needs to be further evaluated.

Bone formation after 4 weeks around blood-plasma-modified titanium implants with varying surface topographies: an in vivo study

The aim of the present study was to investigate and compare the stability and bone ingrowth capacity to screw-shaped titanium implants with five different surface treatments. The implants were: (1) standard turned with a thin blood plasma coat (TP), (2) NaOH-etched dito with pore size 0.2-0.3 microm (E), (3) NaOH-etched with pore size 0.2-0.3 microm and a thin blood plasma coat (EP), (4) electrochemically oxidised with pore size 1-2 microm (O), (5) electrochemically oxidised with pore size 1-2 microm and a thin blood plasma coat (OP). A total of 66 implants were divided into the above-described five groups and inserted for 4 weeks into tibia and femur of 11 rabbits. The implants were evaluated by resonance frequency (RF) measurements at the time of insertion and removal, and analysed histomorphometrically at removal. The RF measurements showed that the implant stability was lower in soft bone compared to dense and increased with time. No significant differences were observed between the different surface modifications. The histomorphometric analysis revealed no statistically significant differences between the implants regarding bone-to-metal contact (BMC) and bone area inside the threads (BA). The above results indicate that thin blood plasma-coated and non-coated screw-shaped titanium implants with turned, NaOH-etched and electrochemically etched surface profiles integrate similarly to bone at 1 month of implantation.

An Experimental Study of the Kinetics of Particle Deposition in a Wall-Jet Cell Using Total Internal Reflection Microscopy

The deposition of polystyrene latex particles of 0.46 µm diameter was studied in situ using a wall-jet cell in combination with total internal reflection microscopy. The particles were deposited onto an indium tin oxide surface in a laminar flow field for up to 13 h. The initial particle flux was found to be mass-transfer-controlled. It was shown that one period of the time-dependent deposition rate period was of first-order nature. The effective particle transfer coefficient during this period appeared to be correlated inversely to the wall shear rate. With the help of three characteristic empirical constants, one of them being a mass transfer coefficient, the overall deposition process was described by a model equation. The concentration dependency was elucidated using a Langmuir-type pseudoisotherm. Copyright 2000 Academic Press.

Changes in conceptions of meaning, effects and treatment of amblyopia. A phenomenographic analysis of interview data from parents of amblyopic children

The research reported is an experimental study on the effects of intensified education of parents of children with amblyopia on their understanding of the nature of the defect, its origins and treatment. Parents in the control group were exposed to the ordinary information provided at two departments of paediatric ophthalmology, whereas parents in the experimental group, attending the same clinics, were asked to read a booklet aiming at enhancing their understanding of amblyopia and its treatment. Experimental as well as control subjects were thereafter interviewed about their understanding of the meaning of amblyopia and amblyopia-related phenomena. Data were generated in single subject, semi-structured, in-depth interviews which were taped and transcribed in extenso. The interviews were analyzed according to the phenomenographic approach: i.e. the outcome is a description of the various conceptions that emerged in the interviews. In almost all cases the categories of meaning could be hierarchically ordered with regard to the level of understanding implied. Parallel to the interviews the subjects had also filled out a questionnaire assessing general and specific attitudes towards disease and treatment (the Health Belief Model, HBM). The results reveal a superior understanding among parents in the experimental group. The experimental group had also changed attitudes towards disease and treatment in a direction that would favour compliance, more than could be observed in the control group. The outcome is discussed in terms of the role of understanding for a compliant behaviour. It is also emphasised that health care personnel would profit from being aware of the nature of common misconceptions of diseases and their treatment, in the sense that they would be better prepared for entering instructional dialogues with patients or, as in this case, other persons responsible for the management of prescriptions provided.

Growth and nutrition of small Betula pendula plants at different relative addition rates of manganese

In a series of experiments, growth of small birch plants (Betula pendula Roth) was controlled by the relative addition rate of manganese, R(Mn) (day(-1)). The R(Mn) treatments were 0.05, 0.10, 0.15 and 0.20 day(-1) with free access to all other nutrients. In an additional treatment, FA, there was free access to all nutrients including Mn. The pH of the nutrient solution ranged between 3.9 and 4.1, and the conductivity was between 100 and 200 micro S cm(-1). After an adjustment phase to steady-state growth, there was a one-to-one relationship between the relative growth rate, R(G) (day(-1)), and the supply of manganese, R(Mn) (day(-1)). The Mn concentration of the plants ranged from 6 to 13 micro g g(DW) (-1) in all treatments with limiting R(Mn) and was approximately 200 micro g g(DW) (-1) in the FA treatment. At steady-state growth, the plants showed specific Mn deficiency symptoms, including leaf mortality, that were more pronounced at severe Mn limitation. Total nonstructural carbohydrate concentrations were low, less than 7.5% of dry weight at Mn limitation, and the fraction of plant dry matter partitioned to roots was much less at Mn limitation than has previously been reported for equivalent rates of N or P supply. Manganese uptake rate per unit root growth rate, dMn/dW(r) ( micro mol g(DW) (-1)) was unaffected by the supply of Mn. At Mn limitation, low rates of plant growth were associated with high values of specific leaf area (37 versus 36 m(2) kg(DW) (-1)), and lower values of leaf weight ratio (40 versus 61%) and net assimilation rate (3 versus 10 kg(DW) (-1) m(-2) day(-1)) than were found at higher R(Mn).

Growth and nutrition of small Betula pendula plants at different relative addition rates of manganese

In a series of experiments, growth of small birch plants (Betula pendula Roth) was controlled by the relative addition rate of manganese, R(Mn) (day(-1)). The R(Mn) treatments were 0.05, 0.10, 0.15 and 0.20 day(-1) with free access to all other nutrients. In an additional treatment, FA, there was free access to all nutrients including Mn. The pH of the nutrient solution ranged between 3.9 and 4.1, and the conductivity was between 100 and 200 micro S cm(-1). After an adjustment phase to steady-state growth, there was a one-to-one relationship between the relative growth rate, R(G) (day(-1)), and the supply of manganese, R(Mn) (day(-1)). The Mn concentration of the plants ranged from 6 to 13 micro g g(DW) (-1) in all treatments with limiting R(Mn) and was approximately 200 micro g g(DW) (-1) in the FA treatment. At steady-state growth, the plants showed specific Mn deficiency symptoms, including leaf mortality, that were more pronounced at severe Mn limitation. Total nonstructural carbohydrate concentrations were low, less than 7.5% of dry weight at Mn limitation, and the fraction of plant dry matter partitioned to roots was much less at Mn limitation than has previously been reported for equivalent rates of N or P supply. Manganese uptake rate per unit root growth rate, dMn/dW(r) ( micro mol g(DW) (-1)) was unaffected by the supply of Mn. At Mn limitation, low rates of plant growth were associated with high values of specific leaf area (37 versus 36 m(2) kg(DW) (-1)), and lower values of leaf weight ratio (40 versus 61%) and net assimilation rate (3 versus 10 kg(DW) (-1) m(-2) day(-1)) than were found at higher R(Mn).

Effect of papillary exposure on intrarenal distribution of glomerular filtration rate and of plasma flow

Removal of the renal pelvis in order to expose the renal papilla has been shown to cause impairment of the renal concentrating ability by an unknown mechanism. To study this phenomenon, urine osmolality (Uosm), single-nephron glomerular filtration rate (SNGFR) in outer and inner cortical nephrons and the inner and outer medullary plasma flow were determined. Measurements were performed on groups of rats before (control) and 15, 45 and 90 min after exposure of the left renal papilla. Rats with an intact ureter were studied in parallel to see whether the variables varied within the 90-min period of the study. In all groups of animals with an exposed papilla, Uosm was lower than in non-exposed animals. Outer cortical SNGFR in rats with exposed papillae, regardless of time, was not different from that in control rats. Inner cortical SNGFR after 45 and 90 min of exposure did not differ from that in controls, but after 15 min of exposure it was lower than in control animals. Outer and inner medullary plasma flow did not differ between rats with exposed papillae and controls, irrespective of exposure time. In conclusion, papillary exposure results in a permanent decrease in urine osmolality. This impairment of the concentrating ability cannot be attributed to prolonged changes in renal haemodynamics.

Increase in proximal tubular fluid reabsorption by renal nerve stimulation. A split oil droplet study

The influence of renal sympathetic nerve stimulation on fluid reabsorption in the proximal tubules was studied in anaesthetized male Sprague-Dawley rats. Direct stimulation with a frequency of 2 Hz was applied, and a modification of the split oil droplet technique was used. The fluid reabsorption was determined as the half-time (t1/2) of the shrinking droplet. In the control situation t1/2 was 30.7 +/- 3.4 s. On stimulation at 2 Hz, t1/2 decreased in all nine rats studied by an average of 25 +/- 5%, to 22.4 +/- 2.6 s (P less than 0.01). The decrease in t1/2 indicates an increased rate of proximal tubular fluid reabsorption. The results support the concept that the anatomically established adrenergic innervation of renal proximal tubules participates in the direct regulation of tubular fluid reabsorption, a role which might be important in the control of the extracellular volume.

CNS-induced natriuresis is not mediated by the atrial natriuretic factor

Studies were performed on anaesthetized Wistar-Kyoto rats to investigate whether the natriuretic response to stimulation of the cerebroventricular system with a hypertonic sodium solution is in part caused by increased plasma concentrations of atrial natriuretic factor (ANF). Through a cannula inserted into a lateral cerebral ventricle a solution with a normal (CSF, 152 mmol l-1) or high (NaCSF, 1,000 mmol l-1) sodium ion content was infused. In the stimulated animals which received NaCSF, the sodium excretion increased more than 13-fold, from 0.07 +/- 0.02 (mean +/- SEM) to 0.97 +/- 0.22 mumol min-1 g-1 kidney wt (P less than 0.01). Potassium excretion rose more than eight-fold, from 0.37 +/- 0.05 to 3.01 +/- 0.13 mumol min-1 g-1 kidney wt (P less than 0.001), and the urine flow rate more than seven-fold, from 1.35 +/- 0.11 to 9.74 +/- 1.23 microliters min-1 g-1 kidney wt (P less than 0.001). The mean arterial blood pressure increased from 100 +/- 3 to 129 +/- 7 mmHg (P less than 0.001). In the control animals which received CSF throughout the experiment there was no significant change in the above variables. The concentrations of ANF in plasma taken at the end of the experiments were determined by a radioimmunoassay. The mean plasma concentration of ANF in animals receiving CSF throughout the experiment was 175 +/- 36 pg ml-1. This was not significantly different from the corresponding value in animals which were given NaCSF (118 +/- 34 pg ml-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Redistribution of glomerular filtration and renal plasma flow in CNS-induced natriuresis

Infusion of hypertonic sodium chloride solution into the third cerebral ventricle results in a marked increase in renal sodium output, indicating an important regulator of extracellular volume homeostasis. The intrarenal events governing the enhanced excretion have not been thoroughly studied previously. In 12 anaesthetized male rats a stainless steel cannula was introduced stereotaxically into the right lateral cerebral ventricle. Urine volume and excretion rates, Na, K, and osmotically active particles were measured during control infusion of artificial cerebrospinal fluid and during stimulation of central mechanisms with I M NaCl (520 nl min-1). At the end of the stimulation period, regional renal plasma flow (86RbCl) and glomerular filtration rate (51Cr-EDTA) were measured with single injection techniques. A second group of 12 non-stimulated rats served as controls. During ICV stimulation, the urine flow rate increased from 1.8 +/- 0.19 to 6.4 +/- 1.01 microliter min-1 (P less than 0.001). The urinary concentrations of Na and K increased, leading to a rise in the excretion rates of these ions from 0.12 +/- 0.025 to 0.96 +/- 0.352 mumol min-1 (P less than 0.001) and 0.40 +/- 0.083 to 1.70 +/- 0.196 (P less than 0.001), respectively. The osmolar excretion rate was 2.9 +/- 0.35 mu Osm min-1 before stimulation and 9.6 +/- 1.09 higher (P less than 0.001) during stimulation. Simultaneously the inner medullary plasma flow rose two-fold from 0.7 +/- 0.06 to 1.4 +/- 0.12 microliter min-1 tissue (P less than 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Superficial and juxtamedullary nephron function during converting enzyme inhibition

The influence of the renin-angiotensin system on whole-kidney and regional single-nephron function was studied in anesthetized Munich-Wistar rats by use of a converting enzyme inhibitor (CEI), captopril (3 mg . h-1 . kg-1 body wt-1). Single-nephron glomerular filtration rate (SNGFR) was measured in superficial (S) and juxtamedullary (JM) nephrons by a micropuncture technique that blocked tubuloglomerular feedback (TGF) activity. Hydrostatic free-flow pressure (FFP) measurements were conducted in S proximal tubules, in JM loops of Henle, and in papillary vasa recta. Glomerular filtration rate (GFR) and urinary electrolyte excretion were measured in the contralateral kidney. In the control situation SNGFR of S nephrons was 35.4 +/- 2.24 nl . min-1 . g kidney wt-1 and of JM nephrons was 75.0 +/- 9.41 nl . min-1 . g-1 kidney wt-1. Thus it was more than twice as high in JM as in S nephrons when the TGF activity was blocked. In this situation administration of CEI had no additional effect on either S or JM nephrons. However, administration of CEI resulted in a significant increase in whole-kidney GFR by 25% (P less than 0.05) and in urine flow rate by 60% (P less than 0.001) under free-flow conditions. Further, intratubular FFP increased significantly in JM nephrons by an average of 2.9 +/- 0.52 mmHg (P less than 0.001), indicating an increase in tubular urine flow in JM nephrons, whereas S nephrons were unaffected. These results suggest an active preglomerular vasoconstriction in JM nephrons under normal free-flow conditions. This seems to be mediated by TGF and modulated by angiotensin II.

The effect of a converting enzyme inhibitor on autoregulation and intrarenal distribution of glomerular filtration in the rat

The role of the renin-angiotensin system in the autoregulation and distribution of the single nephron glomerular filtration rate (SNGFR) in anaesthetized, normotensive rats was investigated. SNGFR in outer cortical (OC) and inner cortical (IC) nephrons of the left kidney were measured with a modified Hanssen technique at three levels of renal arterial pressure (RAP): at a spontaneous arterial pressure; at a value within the autoregulatory limit, 100 mmHg; and at the lower limit of the autoregulatory range, 70 mmHg. This was done in control rats and in rats given a continuous i.v. infusion of the converting enzyme inhibitor (CEI) captopril (3 mg . h-1 X kg-1 BW). In control rats there was complete autoregulation of SNGFR in both OC and IC nephrons when RAP was reduced to 100 mmHg. Further reduction to 70 mmHg elicited different responses among the cortical layers, associated with a decrease in SNGFR. A fractional redistribution of glomerular filtration rate towards IC nephrons was evident. Administration of CEI at spontaneous RAP increased SNGFR in IC nephrons compared with values in control rats, but did not notably alter SNGFR in OC nephrons. Reduction of RAP to 100 mmHg during CEI infusion caused SNGFR to decrease below control values in both OC and IC nephrons, and the autoregulation as found in control rats was impaired. When RAP was lowered to 70 mmHg during CEI administration there was a progressive decrease in SNGFR in all cortical layers, although absolute changes were much greater in IC nephrons than in OC nephrons.(ABSTRACT TRUNCATED AT 250 WORDS)

Time-dependent heterogeneity of filtration rate in the autoregulating rat kidney

Experiments were performed to study the regulation of the single-nephron glomerular filtration rate (SNGFR) in superficial and juxtamedullary nephrons, as the left kidney of Sprague Dawley rats was submitted to a reduced arterial pressure of 70 mmHg by means of an aortic clamp. The SNGFR at different cortical levels was measured 0.5, 1, 5, 20 or 45 min after the reduction, in order to ascertain whether the effects of the regulatory mechanisms are modified with time. A Hanssen technique was used, which allows one determination of filtration rates per animal. At a renal arterial pressure (RAP) of 100 mmHg (= control animals) the SNGFR amounted to 20 +/- 1.2 and 23 +/- 0.8 nl X min-1 X g-1 kidney weight in the outer and inner cortical (OC, IC) nephrons. When RAP was further reduced to 70 mmHg, the autoregulation of SNGFR, determined after 0.5 min, was highly efficient for both OC and IC nephrons (19 +/- 2.0, 23 +/- 2.6). A prolonged reduction in RAP caused a gradual decline in SNGFR. The filtration rate measured after 5 min was 15 +/- 1.4 for OC and 20 +/- 1.8 for IC nephrons. The decline was most pronounced for OC nephrons, which led to a fractional redistribution in favour of IC nephrons. Thus, SNGFRIC/SNGFROC was 1.16 +/- 0.065 when RAP was 100 mmHg and 1.41 +/- 0.126 after 5 min with an RAP of 70 mmHg. It is well documented that suprarenal aortic occlusion is a powerful stimulus for the release of renin. This was manifested as an increase in the arterial pressure proximal to the aortic clamp.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of pressor doses of Angiotensin II on autoregulation and intrarenal distribution of glomerular filtration rate in the rat

This study was designed to investigate the effect of pressor doses of exogenous Angiotensin II (AII) on autoregulation and intrarenal distribution of single nephron glomerular filtration rate (SNGFR) in anesthetized, normotensive rats. SNGFR at all cortical levels of the left kidney was measured with a modified Hanssen technique at three renal arterial pressures (RAP): Spontaneous, 100 +/- 1 mmHg and 70 +/- 1 mmHg. In control rats, both outer cortical (OC) and inner cortical (IC) nephrons showed complete autoregulation of SNGFR when RAP was reduced to 100 +/- 1 mmHg. Further reduction to 70 +/- 1 mmHg resulted in different responses among the cortical layers, accompanying a decrease in SNGFR. The SNGFRIC/SNGFROC ratio increased from 1.36 +/- 0.053 to 1.52 +/- 0.047 and a fractional redistribution of glomerular filtration rate towards IC nephrons was seen. When the kidney was submitted to a RAP of 70 +/- 1 mmHg, there was a concomitant increase in central arterial pressure (CAP) from 120 +/- 4.3 to 134 +/- 3.2 mmHg. A continuous i.v. infusion of AII (0.5 microgram . min-1 . kg-1 BW) increased mean arterial pressure from 123 +/- 1.4 to 142 +/- 3.8 mmHg, an effect corresponding to that on peripheral vascular resistance during reduction of RAP to 70 +/- 1 mmHg in control rats. This dose reduced SNGFR at all cortical levels, but did not per se lead to redistribution of SNGFR. A reduction in RAP to 100 +/- 1 mmHg during AII administration resulted in impaired autoregulation of SNGFR in both OC and IC nephrons.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of tubulo-glomerular feedback on the autoregulation of filtration rate in superficial and deep glomeruli

Single nephron glomerular filtration rate (SNGFR) of superficial and juxtamedullary nephrons were measured at normal and reduced perfusion pressure in the left kidney of young Sprague Dawley rats. Perfusion pressure was lowered by constricting the aorta proximal to the branching of the left renal artery. The influence of the tubulo-glomerular feedback mechanism on SNGFR was quantitated by measuring SNGFR during intact and interrupted urine flow to the macula densa region. By using a modified Hanssen technique, SNGFR was measured under free-flow conditions. In other experiments, the urine flow to the distal nephron was blocked by a micropuncture technique, which was used for collection of the tubular fluid for measuring the filtration rate. All nephron populations autoregulated SNGFR from 70-80 to 130 mmHg, which was the upper limit of this investigation, when urine flow throughout the nephron was intact. The autoregulation in this pressure range was lost when tubular fluid was prevented from reaching the distal nephron. It was shown that the influence of negative feedback on SNGFR by the macula densa mechanism at normal blood pressure is greater in deep nephrons than in superficial ones.

The influence of perinatal factors on breast feeding

The effect on breast feeding of various factors connected with delivery and the immediate post partum period were investigated in a group of 1701 parturients. Children born by caesarean section or assisted delivery, those of low birth weight or asphyxiated at birth started breast feeding significantly less often than healthy children delivered normally. The length of breast feeding was not affected by these factors once it was started, 49% breast feeding for six months or more. Exceptionally young and old mothers breast fed less well than mothers in general. Mothers whose husbands attended the delivery breast fed more often and longer than others. Failure to start breast feeding occurred in only 2.4% of the material. In this material with high breast feeding rates it can be concluded that obstetric and perinatal abnormalities have a small but nevertheless significant effect on the incidence of breast feeding.

The tubulo-glomerular feedback mechanism-a determinant for the autoregulation of the glomerular filtration rate in superficial and juxtamedullary nephrons

The intrinsic myogenic hypothesis and the tubuloglomerular feedback mechanism (TGF) give the presently most cherished explanation to the autoregulation of renal blood flow and glomerular filtration rate. A series of experiments was performed on young, normohydrated rats in order to evaluate the importance of TGF as an autoregulatory factor of the single nephron glomerular filtration rate (SNGFR) in superficial and juxtamedullary nephron populations. Micropuncture techniques were applied to tubular structures of the renal surface and on the papilla for the measurement of hydrostatic pressures and SNGFR. The SNGFR was also measured with a modified Hanssen technique. A TV-technique was used to record the urine free flow rate in the loop of Henle. The net driving forces for glomerular filtration at the afferent end of the glomerular capillaries were estimated to be 19 and 47 mm Hg for superficial and juxtamedullary nephrons respectively, when the urine flow at the macula densa was zero. The SNGFR of the two nephron populations amounted to 29.6 and 84.1 nl . min-1 . g-1 K.W., as measured with the micropuncture technique. With a modified Hanssen technique the corresponding values were 25.8 and 27.7 nl . min-1 . g-1 K.W. (kidney weight). The SNGFR was found to be well autoregulated when the urine flow at the macula densa was intact, but not when the urine flow was interrupted. The flow rate in the loop of Henle was in free flow conditions 7.3 nl . min-1 . g-1 K.W. which shall be compared with 19.2 nl . min-1 . g-1 K.W. when the urine flow to the macula densa was zero. We conclude that SNGFR is mainly autoregulated by the TGF-mechanism in young, normohydrated rats at lower arterial pressures. In normal conditions TGF is highly activated for juxtamedullary nephrons, but not for the superficial ones. The high urine flow rate in the loop of Henle at reduced flow rates at the macula densa may invalidate the use of loop blockade in studies of water and solute transfer across the loop walls.