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PubMed1990

[The relationship between creatinine clearance and glomerular filtration rate in the critically ill patient].

A study was undertaken to show that the determination of glomerular filtration rate with radio-labelled sodium chromate ethylenediaminetetra-acetic acid is a repeatable, easily performed and accurate examination in the critically ill patient. Differences in glomerular filtration rate were relatively small, with a phase difference of between -10,59 and 5,34. Creatinine clearance showed a greater variation over a corresponding period, with a difference of between -27,50 and -4,10. The study indicated that this method of determining glomerular filtration rate can be very useful in an intensive care unit, because it seems to be more accurate and easier to perform. Information is obtained more quickly than when the glomerular filtration rate is determined by means of creatinine clearance.

Acute Disease↗
PubMed1990

[A simplified method for the radionuclide determination of glomerular filtration].

Glomerular filtration is one of the chief components of renal function. The biochemical methods of its determination (clearance of insulin and endogenous creatinine) have a number of shortcomings. The use of labeled glomerulotropic agents simplifies methods of the determination of glomerular filtration. A formula and a table of glomerular filtration value per 1 kg of body mass were calculated. The authors presented the results of glomerular filtration calculation for 132 patients. They showed good correlation. The correlation factor is r = + 0.916 (mr = 0.009).

Glomerular Filtration Rate↗
PubMed1990

[The effect of acetylsalicylic acid and dipyridamole on glomerular filtration and proteinuria in chronic glomerulonephritis].

The authors treated 14 patients with chronic proliferative glomerulonephritis for one year with acetylsalicylic acid--400 mg/day--and dipyridamole--225 mg/day. They investigated changes of glomerular filtration and proteinuria before treatment, during treatment and one year after its completion. They found that in the course of treatment proteinuria did not change and glomerular filtration declined insignificantly. During the subsequent year proteinuria and glomerular filtration declined significantly. The above findings can be partly explained by changes in the synthesis of renal prostacyclin and thromboxane. The combination of acetylsalicylic acid and dipyridamole in the amounts used did not have a favourable effect on glomerular filtration in patients with chronic proliferative glomerulonephritis.

Adult↗
PubMed1989

Role of the renin-angiotensin system in the regulation of glomerular filtration.

Angiotensin II (Ang II) controls renal plasma flow, which depends on perfusion pressure and on renal vascular resistances; the glomerular filtration rate of single nephrons (SNGFR) also depends on these two parameters. The glomerulus can synthesize all components of the renin-angiotensin system. Renin is produced by mesangial cells and cells of afferent arterioles, angiotensinogen by mesangial cells, and angiotensin I-converting enzyme (ACE) by endothelial and mesangial cells. Ang II binds to afferent and efferent arterioles and to mesangial cells, which subsequently contract and enhance their production of vasodilator prostaglandins. Ang II participates in the regulation of the SNGFR by acting on arteriolar resistance, on the glomerular capillary surface area, and finally on the ultrafiltration coefficient. The synthesis of renin is initiated when the cAMP concentration increases under the influence of hormones (parathyroid hormone, catecholamines), of mediators (e.g., prostanoids), or of changes in composition of tubular fluid (in sodium, chlorine, or calcium) detected by the macula densa. Moreover, renin synthesis is stimulated by decreases in intracellular calcium concentration. The renin-angiotensin system plays an important role in the regulation of glomerular filtration. A decrease in renal plasma flow is followed by an increase in glomerular efferent arteriole resistance, so that perfusion pressure and glomerular filtration remain constant. Furthermore, if the decrease in renal plasma flow is more marked, vasodilator prostaglandins, whose synthesis is stimulated by Ang II, dilate afferent arterioles, which sustains glomerular filtration. Prostaglandins are also apt to bind to the juxtaglomerular apparatus and to increase the intracellular cAMP level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Assessment of renal function by serum creatinine and creatinine clearance: glomerular filtration rate estimated by four procedures.

We compared creatinine concentrations in serum and urine and creatinine clearances determined by two Jaffé (Beckman's "Astra," Boehringer Mannheim Diagnostics) and two enzymatic (Kodak, Boehringer Mannheim Diagnostics) methods. Serum creatinine and creatinine clearances determined by each method were also compared with the glomerular filtration rate as measured with use of sodium [125I]iothalamate in patients with a wide range of renal function. Results between methods correlated excellently, but we saw clear method-dependent biases of up to 2.9 mg/L for serum. The highest serum creatinine values and the lowest creatinine clearances were obtained with Boehringer Mannheim Diagnostics' Jaffé method. The reciprocal of the serum creatinine and the creatinine clearance also correlated well with the glomerular filtration rate, but all methods over-estimated the glomerular filtration rates to varying degrees. Appropriate standardization of methods appears to be as important as method principle for establishing an accurate relationship between creatinine determinations and glomerular filtration rate.

Adolescent↗
PubMed1989

The perioperative changes in glomerular filtration and renal blood flow in patients with obstructive jaundice.

Experimental alterations in renal haemodynamics have been observed in obstructive jaundice and these may be the pathophysiological mechanism of increased renal susceptibility to injury in obstructive jaundice. Dynamic 99mTc-DTPA renal scintigraphy was done before and eight weeks after elective hepatobiliary surgery in six patients with obstructive jaundice (bilirubin greater than 100 mumol/l) and in six non-jaundiced control patients to assess changes in glomerular filtration and renal blood flow. Glomerular filtration was lower preoperatively in the jaundiced patients than in the control patients. Glomerular filtration increased postoperatively in jaundiced patients, but decreased in control patients. Renal blood flow was reduced postoperatively in control patients, but not in jaundiced patients. The changes in renal blood flow were different for each group of patients. These results provide clinical evidence of altered renal haemodynamics and a reversible impairment of glomerular filtration in obstructive jaundice. The changes seen in renal blood flow may be the underlying mechanism of increased renal susceptibility to injury.

Adult↗
PubMed1989

[Estimation of the filtration variables in the rat lung].

The filtration variables, filtration coefficient (K), perimicrovascular pressure (Ppmv) and reflection coefficient (sigma) were estimated independently in previous reports using the Starling Equation or the micropuncture method. We estimated these variables simultaneously. We measured filtration rate by a gravimetric method in isolated rat lung lobes in zone 1 conditions (alveolar pressure = 20 cmH2O) at two vascular pressures, Pvasc = 15 or 8 cmH2O and perfused the lobes with plasma containing a low or high concentration of protein. By extrapolating the log of the rate of weight gain to time = 0, we obtain the initial filtration rate. Assuming that protein filtered into perimicrovascular space only by convection, we substituted into the Starling Equation as follows: Q = K[(Pmv-Ppmv)-sigma 2 pi mv], where Pmv and pi mv are hydrostatic and plasma protein osmotic pressures in microvascular space. pi mv was estimated by Yamada's equation. We obtained K = 26.3 +/- 8.7 mg/(min.cmH2O.g), PPMV = 6.2 +/- 0.7 cmH2O, sigma = 0.46 +/- 0.07. The chief advantages of this method are that it does not require a separate estimation of isogravimetric pressure or a direct measurement of interstitial pressure, and that all variables are obtained simultaneously.

Animals↗
PubMed1989

A modified method for human bone marrow filtration prior to bone marrow transplantation.

A technique is described for filtering harvested bone marrow using disposable materials, namely a 4 x 4 inch piece of sterile gauze that is gently packed into the barrel of a 60-ml plastic disposable syringe, which is connected directly to a blood collection bag. The filtration of marrow directly into the collection bag eliminates additional filtration steps and therefore may potentially reduce the incidence of inadvertent microbial contamination. In this study we describe this filtering technique and compare it to the method described by Thomas and Storb. Numbers of granulopoietic progenitors (CFU-GM) and erythropoietic progenitors (BFU-E), total white cell counts, percentage of cells positive for the CD3 (OKT3) lymphocyte surface membrane marker, and volume changes were studied following filtration by each method. The two techniques were shown to be comparable in terms of these parameters. Furthermore, when compared with historical controls, this method resulted in a reduced incidence of microbial contamination compared to filtration using successive stainless steel screens.

Adolescent↗
PubMed1978

Efficiency of bacterial filtration in various commercial air filters for hospital air conditioning.

Filtration efficiency of high-efficiency particulate air (HEPA) filters is said to be over 99.97% of removal rate against the mist of thermogenerating-type of dioctyl phthalate with average particles diameter of 0.3 micrometer, as tested by the U.S. Military Standard 282 (1956). Filtration of bacterial aerosols through commercial air filters was tested to examine the efficiency of bacterial filtration with eight kinds of air filters. Percentage of bacterial filtration efficiency (% BFE) of three kinds of HEPA filters showed 100% BFE, while NBS-95 and NBS-85 showed over 99% BFE. BFE of NBS-75 air filter was 91.75%.

Aerosols↗
PubMed1979

[Kidney filtration -- mechanisms and methods of investigation (author's transl)].

Quantitative data are presented on the glomeruli in the human, dog and rat kidney. Micropuncture techniques for the determination of filtration pressure and filtration rate are described. The final part of this paper deals with the dynamics of glomerular ultrafiltration. The roles are discussed of filtration equilibrium/disequilibrium and of the renin-angiotensin systems in the filtration process.

Acid-Base Equilibrium↗
PubMed1985

Acute effect of captopril on single kidney glomerular filtration rate in arterial hypertension.

Recent studies have reported that captopril can acutely induce a marked decrease of glomerular filtration rate in kidneys affected by renal artery stenosis, an effect detectable by scintigraphic techniques. Experience which confirms and extends this observation, obtained in five patients with renovascular hypertension, is reported here. For comparison, eight essential hypertensives and six patients with non-vascular unilateral renal diseases were studied. In each patient the ratio of glomerular filtration rate between the two kidneys was estimated during two consecutive scintigraphic studies with the glomerular tracer 99mTc-DTPA: in all renovascular patients captopril induced a marked decrease of glomerular filtration rate on the affected side, whereas negligible changes were observed in all other subjects. These results confirm that captopril may almost completely suppress glomerular filtration in kidneys affected by unilateral renal artery stenosis, an effect which may not be apparent clinically because of compensation by the other kidney, but which is scintigraphically detectable. Renal scintigraphy after captopril is easy to perform and non-invasive. It therefore seems to be a promising tool for the screening of renovascular hypertension.

Captopril↗
PubMed1984

Effect of membrane filtration of antimalarial drug solutions on in vitro activity against Plasmodium falciparum.

Antimalarial activities of chloroquine, mefloquine, amodiaquine, and quinine in vitro against Plasmodium falciparum were diminished as a consequence of membrane filtration. Filtered drug solutions gave ID(50) values up to 25-fold greater than those of non-filtered (ethanol-sterilized) drug solutions. Loss of activity by filtration was overcome by increasing the drug concentration prior to filtration. Water solutions filtered through Millex-GS filter units consistently showed an absorbance maximum at 277 nm, accompanied by a lesser peak at 225 nm. Water filtrates from Nucleopore and Millex-GV filters showed no absorbance at 277 nm and only slight absorbance was evident for the Gelman filter unit. Activity losses were attributed to extractable contaminating moieties in the membrane filters and/or drug binding to the membrane filters.

Antimalarials↗
PubMed1976

[The transplantability of bone marrow and spleen cells after filtration through silon tissue].

Investigations were carried out on the separation of haematopoietic stem cells from suspensions of the bone-marrow and spleen by means of filtration with silon tissue. The presence of stem cells in the filtrates was determined by the spleen colony test according to the method of Till and McCulloch in irradiated mice. The investigations revealed that a selective separation of haematopoietic stem cells could not be achieved when proceeding in this way. From the results of further test series, in which suspensions were also used which had been gained from haematopoietic tissues of hypersplenic mice, the conclusion could be drawn that the haematopoietic stem cells obtained by filtrating the bone-marrow will have another affinity to the spleen tissue of irradiated mice than the haematopoietic stem cells gained by filtrating the spleen tissue.

Animals↗
PubMed1983

The effect of water deprivation on local renal blood flow and filtration in the laboratory rat.

The effects of longlasting dehydration on total and local renal blood flow and glomerular filtration rate have not been studied previously in the laboratory rat. We therefore determined zonal renal blood flow (ZRBF) in cortical and medullary zones by the 125I-iodoantipyrine and H2 gas washout techniques. After 8 days of water deprivation renal blood flow (RBF) was reduced by 65% and renal vascular resistance (RVR) had increased by 110%. Half the RVR increase could be ascribed to increased blood viscosity as reflected by increased hematocrit (42 to 60%). Fractional ZRBF decreased by 5% in the outer half and increased by 5% in the inner half of the cortex. Measurements of the relative single nephron glomerular filtration rate (sngfr) of superficial and deep nephrons, determined by the 14C-ferrocyanide technique, indicated no detectable changes in filtrate distribution. Both ZRBF and sngfr heterogeneity had increased in dehydrated as compared to control rats. In one rat studied with the H2 gas washout method, local ischemia and intermittent blood flow occurred. Similarly, cortical patches of nonfiltering nephrons were observed in another rat. These findings suggest that the increased heterogeneity of intrarenal flow and filtration may involve, and in part be due to, intermittent local changes in blood flow.

Animals↗
PubMed1983

[A method for erythrocyte filtration].

Erythrocyte deformability is one of the most important factors on determining blood viscosity. Many microcirculation damages are caused by alteration of viscosity. We propose a method for evaluate erythrocyte filtration using Nucleopore membranes, to study erythrocyte deformability. Normal ranges are calculated in young healthy subjects. Mean filtration time is determined on 5 filtrations for every subject. Filtration rate is expressed by sec/ml and correlated whit haematocrit. The method is not easily utilizable, but it can be useful in the knowledge of the role of the erythrocyte deformability in the altered microcirculation.

Blood Viscosity↗
PubMedDate not supplied

Erbium filtration in iodine contrast studies.

In iodine contrast studies, an improvement in contrast is theoretically possible by narrowing the energy spectrum around the k-edge of iodine. Heavy metal filtration is a method of narrowing the energy spectrum but other parameters of the examination may be altered. These other parameters must be examined. After establishing the effect of heavy metal (erbium) filtration on the beam energy, the filter is evaluated in a simulated clinical situation. Patient exposure, image contrast, and tube loading are monitored while obtaining radiographs of a phantom comparable to a standard radiograph of the phantom. From this study, it was determined that erbium filtration could be used to decrease patient exposure markedly without significant loss of contrast or an increase in tube loading. Also determined was a set of exposure factors at which the erbium filtration was most effective.

Contrast Media↗
PubMed1982

Glomerular filtration in birds--its control.

Morphologically there are marked differences between the avian and mammalian kidneys. It is apparent that these differences affect the means by which these organs carry out their homeostatic function of maintaining the internal environment constant. One of the morphological differences is a larger range in size of nephrons within the avian kidney. It is clear that there is a significant degree of intermittent filtration within this very heterogeneous population of nephrons. This leads to larger variation in the total-kidney glomerular filtration rate in birds than in mammals. The glomerular intermittence in birds appears to be controlled by the antidiuretic hormone arginine vasotocin acting at the level of the afferent arteriole. The process of ultrafiltration at the glomerulus in birds is most likely governed by the same parameters that have been quantified for the glomerulus of mammals, because ultrastructural studies indicate that the filtration barrier is similar in both groups. However, for birds it is not known whether certain hormones and other biochemical messengers can effect the filtration process at the level of the glomerulus as demonstrated for mammals. Moreover, it is not known whether feedback regulation occurs at the level of the individual nephron. The morphological attributes of the individual nephrons within the kidney are consistent with the theories of feedback regulation, but the physiological occurrence of this has not been tested.

Animals↗
PubMedDate not supplied

Compensatory renal hypertrophy in dogs: single nephron glomerular filtration rate.

Kidney weight, length of superficial and juxtamedullary proximal tubules, glomerular diameter, kidney filtration rate and PAH clearance, sodium excretion and intrarenal distribution of filtration (with (14)C-ferrocyanide) were measured in the remaining hypertrophic kidneys of dogs 10 days after unilateral nephrectomy. Whereas kidney weight increased to 75 percent of the original total renal mass, proximal tubule length and mean glomerular diameter remained unchanged. PAH and creatinine clearance, and absolute, but not fractional, sodium excretion, rose significantly. The ratio superficial/juxtamedullary filtration rate remained unchanged, indicating parallel increases of filtration in both cortical regions of hypertrophied kidneys.

Adaptation, Physiological↗