Chitosan Tethered Colloidal Gold Nanospheres for Drug Delivery Applications

Gold Nanospheres (AuNS) have been widely explored as an emerging system for various biomedical applications including drug delivery, bioimaging and photomedicine. However, method of synthesizing nanoparticles and its toxicity including bioaccumulation has been a problem of concern. In the present study, we explored the appropriateness of 12.0 ±1.99 nm chitosan reduced AuNS in vivo models with respect to its bioavailability and toxicity against various concentrations (2.5-7.5 mg/kg). Administration of AuNS did not show any signs of morbidity. Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis of blood (0.156 ± 0.154), urine (0.084 ± 0.08) and tissues indicates gradual dissipation and obligatory clearance within 24 h time interval. Nevertheless, pres- ence of AuNS in blood after 24 h confirms the bioavailability of AuNS demonstrating the evidence for no immune clearance and efficient tissue uptake. Further, brain shows the lowest quantity of injected AuNS. From this result, we determine this chitosan monolayer protected AuNS could cross the blood brain barrier and enter to the neural tissues. Interestingly there was no evidence of toxicity in any of the organs. In conclusion, our data suggest that AuNS injected though tail vain were easily taken up by tissues and does not produce sub-acute physiological damage even at high concentrations tested, supporting chitosan reduced AuNS as biocompatible, nontoxic nanoconjugates for targeted drug delivery and other biomedical applications.

Natural colloidal P and its contribution to plant P uptake

Phosphorus (P) bioavailability depends on its concentration and speciation in solution. Andisols and Oxisols have very low soil solution concentration of free orthophosphate, as they contain high concentrations of strongly P-sorbing minerals (Al/Fe oxyhydroxides, allophanes). Free orthophosphate is the form of P taken up by plants, but it is not the only P species present in the soil solution. Natural colloidal P (P associated with Al, Fe, and organic matter of sizes ranging from 1 to 1000 nm) constitutes an important fraction of soil solution P in these soils; however, its availability has not been considered. We measured the uptake of P by wheat (Triticum aestivum) from radiolabeled nonfiltered (colloid-containing) and 3-kDa filtered (nearly colloid-free) soil-water extracts from Andisols and Oxisols. In the Andisol extracts, P uptake was up to 5-fold higher from the nonfiltered solutions than the corresponding 3-kDa filtered solutions. In the Oxisol extract, no difference in P uptake between both solutions was observed. Also the diffusional flux of P as measured with the DGT technique was larger in the nonfiltered than in the 3-kDa filtered solutions. Our results suggest that colloidal P from Andisols is not chemically inert and contributes to plant uptake of P.

Patient-specific dosimetry for intracavitary 32P-chromic phosphate colloid therapy of cystic brain tumours

PURPOSE

(32)P-chromic phosphate colloid treatments of astrocytoma and craniopharyngioma cystic brain tumours in paediatric patients are conventionally based on a sphere model under the assumption of uniform uptake. The aims of this study were to determine the distribution of the absorbed dose delivered by (32)P on a patient-specific basis and to evaluate the accuracy with which this can be predicted from a pretherapy administration of (99m)Tc-Sn colloid.

METHODS

Three patients were treated with (32)P-chromic phosphate colloid following (99m)Tc-Sn colloid administrations. Convolution dosimetry was performed using pretherapy and posttherapy sequential SPECT imaging, and verified with EGSnrc Monte Carlo radiation transport simulations. Mean absorbed doses to the cyst wall and dose-volume histograms were also calculated and compared with those obtained by the sphere model approach.

RESULTS

Highly nonuniform uptake distributions of both the (99m)Tc and (32)P colloids were observed and characterized by dose-volume histograms to the cyst wall. Mean absorbed doses delivered to the cyst wall, obtained with the convolution method, were on average 21 % (SD 18 %) and 50 % (SD 30 %) lower than those predicted by the (99m)Tc distribution and the uniform assumption of the sphere model, respectively.

CONCLUSION

Absorbed doses delivered to the cyst wall by (32)P are more accurately predicted from image-based patient-specific convolution dosimetry than from simple sphere models. These results indicate the necessity to perform personalized treatment planning and verification for intracavitary irradiation of cystic brain tumours treated with radiocolloids. Patient-specific dosimetry can be used to guide the frequency and levels of repeated administrations and would facilitate data collection and comparison to support the multicentre trials necessary to progress this therapy.

A combined crystalloid and colloid pd solution as a glucose-sparing strategy for volume control in high-transport apd patients: a prospective multicenter study

BACKGROUND

Evidence is accumulating that the continuous exposure to high glucose concentrations during peritoneal dialysis (PD) is an important cause of ultrafiltration (UF) failure. The cornerstone of prevention and treatment of UF failure is reduction of glucose exposure, which will also alleviate the systemic impact of significant free glucose absorption. The challenge for the future is to discover new therapeutic strategies to enhance fluid and sodium removal while diminishing glucose load and exposure using combinations of available osmotic agents.

OBJECTIVES

To investigate in patients on automated PD (APD) with a fast transport pattern whether there is a glucose-sparing advantage to replacing 7.5% icodextrin (ICO) during the long dwell with a mixed crystalloid and colloid PD fluid (bimodal UF) in an attempt to promote daytime UF and sodium removal while diminishing the glucose strength of the dialysate at night.

DESIGN

A 2 parallel arm, 4 month, prospective nonrandomized study.

SETTING

PD units or university hospitals in 4 French and Belgian districts.

RESULTS

During the 4-month intervention period, net UF and peritoneal sodium removal during the long dwell when treated by bimodal UF was about 2-fold higher than baseline (with ICO). The estimated percent change (95% confidence interval) from baseline in net daytime UF for the bimodal solution was 150% (106% - 193%), versus 18% (-7% - 43%) for ICO (p < 0.001). The estimated percent change from baseline in peritoneal sodium removal for the bimodal solution was 147% (112% - 183%), versus 23% (-2% - 48%) for ICO (p < 0.001). The estimated percent change from baseline in UF efficiency (24-hour net UF divided by the amount of glucose absorbed) was significantly higher (p < 0.001) when using the bimodal solution was 71%, versus -5% for ICO.

CONCLUSION

Prescription of bimodal UF during the day in APD patients offers the opportunity to optimize the long dwell exchange in a complete 24-hour APD cycle. The current study demonstrated that a bimodal solution based on the mixing of glucose (2.6%) and icodextrin (6.8%) achieved the double target of significantly improving UF and peritoneal sodium removal by exploring a new concept of glucose-sparing PD therapy.

Compressed collagen sponges as gastroretentive dosage forms: in vitro and in vivo studies

The objective of the present investigations was to develop oblong tablets which expand after contact with gastrointestinal fluids within a few minutes to a length of 4-6 cm and which should remain in the stomach for a prolonged period of time due to their size. The tablets were prepared from riboflavin-containing collagen sponges using a computer controlled single punch tablet machine. The collagen material was compressed to oblong tablets with dimensions of 3.5 mm x 9 mm x 18 mm. In vitro investigations were carried out to characterise drug release. The model drug riboflavin was released from the collagen tablets over 12h. The gastrointestinal retention time of the new dosage form was indirectly estimated by determining the duration of riboflavin excretion after oral intake of the tablet. A crossover in vivo study with 12 healthy male and female subjects was performed. The renal excretion of riboflavin was measured after oral administration of collagen tablets and small sustained release hydrocolloid tablets as reference preparation. The amount of riboflavin excreted into the urine was enhanced after administration of the expanding collagen tablets in comparison with the hydrocolloid tablets. The differences were statistically significant after 5, 6, 8, 9, 10 and 12 h.

Parameters influencing the stealthiness of colloidal drug delivery systems

Over the last few decades, colloidal drug delivery systems (CDDS) such as nano-structures have been developed in order to improve the efficiency and the specificity of drug action. Their small size permits them to be injected intravenously in order to reach target tissues. However, it is known that they can be rapidly removed from blood circulation by the immune system. CDDS are removed via the complement system and via the cells of the mononuclear phagocyte system (MPS), after their recognition by opsonins and/or receptors present at the cell surface. This recognition is dependent on the physicochemical characteristics of the CDDS. In this study, we will focus on parameters influencing the interactions of opsonins and the macrophage plasma membrane with the surface of CDDS, whereby parameters of the polymer coating become necessary to provide good protection.

Irreversible adsorption of particles on heterogeneous surfaces

Methods of theoretical and experimental evaluation of irreversible adsorption of particles, e.g., colloids and globular proteins at heterogeneous surfaces were reviewed. The theoretical models were based on the generalized random sequential adsorption (RSA) approach. Within the scope of these models, localized adsorption of particles occurring as a result of short-ranged attractive interactions with discrete adsorption sites was analyzed. Monte-Carlo type simulations performed according to this model enabled one to determine the initial flux, adsorption kinetics, jamming coverage and the structure of the particle monolayer as a function of the site coverage and the particle/site size ratio, denoted by lambda. It was revealed that the initial flux increased significantly with the site coverage theta(s) and the lambda parameter. This behavior was quantitatively interpreted in terms of the scaled particle theory. It also was demonstrated that particle adsorption kinetics and the jamming coverage increased significantly, at fixed site coverage, when the lambda parameter increased. Practically, for alpha = lambda2theta(s) > 1 the jamming coverage at the heterogeneous surfaces attained the value pertinent to continuous surfaces. The results obtained prove unequivocally that spherically shaped sites were more efficient in binding particles in comparison with disk-shaped sites. It also was predicted that for particle size ratio lambda < 4 the site multiplicity effect plays a dominant role, affecting significantly the structure of particle monolayers and the jamming coverage. Experimental results validating main aspects of these theoretical predictions also have been reviewed. These results were derived by using monodisperse latex particles adsorbing on substrates produced by covering uniform surface by adsorption sites of a desired size, coverage and surface charge. Particle deposition occurred under diffusion-controlled transport conditions and their coverage was evaluated by direct particle counting using the optical and electron microscopy. Adsorption kinetics was quantitatively interpreted in terms of numerical solutions of the governing diffusion equation with the non-linear boundary condition derived from Monte-Carlo simulations. It was proven that for site coverage as low as a few percent the initial flux at heterogeneous surfaces attained the maximum value pertinent to homogeneous surfaces. It also was demonstrated that the structure of larger particle monolayers, characterized in terms of the pair correlation function, showed much more short-range ordering than predicted for homogeneous surface monolayers at the same coverage. The last part of this review was devoted to detection of polyelectrolyte multilayers on various substrates via particle deposition experiments.

Neutral Postgrafted Colloidal Particles for Gene Delivery

Surface modification of cationic lipoplexes has been carried out by means of a postgrafting reaction. The original lipoplexes described comprise a cationic lipid, a neutral lipid, poly(ethylene glycol)-cholesterol (with or without a targeting ligand) and DNA. Modifying their surface via a chemical, postgrafting reaction did not alter their size (approximately 100 nm) nor their ability to compact DNA, but did give a reduced zeta potential (approximately 0 mV) to afford surface neutral particles. With the modified lipoplexes nonspecific NIH3T3 cell surface binding in vitro was inhibited. Intravenous injection of the neutralized lipoplexes in mice showed decreased accumulation of the particles in the lung as compared to PEGylated cationic lipoplexes. Tumor targeting was also achieved in vivo by the addition of an RGD-PEG-Cholesterol as a lipid-ligand in the postgrafted lipoplex formulation.

Radiolabelling and biodistribution of 111In-antimony trisulphide colloid

The aim of this study was to prepare 111In-antimony trisulphide colloid (111In-ATC) and evaluate its chemical properties in comparison with 99mTc-ATC. After reconstitution of an antimony trisulphide cold Kit with 111In-chloride, 111In-ATC was formed with >95% radiochemical purity in the presence of neutralising phosphate buffer. The product was found to be stable for 4.7 days when stored at room temperature, 80% of radioactive particles were < 20 nm in diameter and the mouse biodistribution assay was identical to that of 99mTc-ATC. In conclusion, pharmaceutical-grade 111In-ATC was successfully prepared and assessed to have properties that are suitable for dual-isotope lymphoscintigraphy studies at the clinical level.

Quil A–lipid powder formulations releasing ISCOMs and related colloidal stuctures upon hydration

The aim of the present study was to prepare solid Quil A-cholesterol-phospholipid formulations (as powder mixtures or compressed to pellets) by physical mixing or by freeze-drying of aqueous dispersions of these components in ratios that allow spontaneous formation of ISCOMs and other colloidal structures upon hydration. The effect of addition of excess cholesterol to the lipid mixtures on the release of a model antigen (PE-FITC-OVA) from the pellets was also investigated. Physical properties were evaluated by X-ray powder diffractometry (XPRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and polarized light microscopy (PLM). Characterization of aqueous colloidal dispersions was performed by negative staining transmission electron microscopy (TEM). Physically mixed powders (with or without PE-FITC-OVA) and pellets prepared from the same powders did not spontaneously form ISCOM matrices and related colloidal structures such as worm-like micelles, ring-like micelles, lipidic/layered structures and lamellae (hexagonal array of ring-like micelles) upon hydration as expected from the pseudo-ternary diagram for aqueous mixtures of Quil A, cholesterol and phospholipid. In contrast, spontaneous formation of the expected colloids was demonstrated for the freeze-dried lipid mixtures. Pellets prepared by compression of freeze-dried powders released PE-FITC-OVA slower than those prepared from physically mixed powders. TEM investigations revealed that the antigen was released in the form of colloidal particles (ISCOMs) from pellets prepared by compression of freeze-dried powders. The addition of excess cholesterol slowed down the release of antigen. The findings obtained in this study are important for the formulation of solid Quil A-containing lipid articles as controlled particulate adjuvant containing antigen delivery systems.

Cytotoxicity of colloidal CdSe and CdSe/ZnS nanoparticles

Cytotoxicity of CdSe and CdSe/ZnS nanoparticles has been investigated for different surface modifications such as coating with mercaptopropionic acid, silanization, and polymer coating. For all cases, quantitative values for the onset of cytotoxic effects in serum-free culture media are given. These values are correlated with microscope images in which the uptake of the particles by the cells has been investigated. Our data suggest that in addition to the release of toxic Cd(2+) ions from the particles also their surface chemistry, in particular their stability toward aggregation, plays an important role for cytotoxic effects. Additional patch clamp experiments investigate effects of the particles on currents through ion channels.

[Effect of acid suppression therapy for eradicating Helicobacter pylori infection on bismuth absorption from colloidal bismuth pectin]

OBJECTIVE

To investigate whether acid suppression therapy influences the absorption of bismuth from colloidal bismuth pectin (CBP).

METHODS

48 male SD rats were randomly divided into five groups to be administer with different medicines once a day for 14 days: group A1 (administered with CBP only and killed on the cessation day of administration), group B1 (administered with CBP only and killed 8 weeks after the cessation of administration), group A2 [administered with CBP + amoxicillin (AMO) + metronidazole (MTR) + losec and killed on the cessation day of administration], group B2 (administered with CBP + AMO + MTR + losec and killed 8 weeks after the cessation of administration), and control group (administered with distilled water). The kidney issue sections were counterstained after AMG development. The bismuth deposited in tissues was observed by microscopy. The gray level of kidney tissue sections were measured and compared through image processing program. The deposition of bismuth and the degrees of cell organ's impairment were observed by electron microscopy. By using electron probe microanalysis bismuth was identified from the chemical elements in the specimens.

RESULTS

Under the light microscopy, black-brown granules were discovered in the cell bodies of the proximal convoluted renal tubule. The amounts of bismuth accumulated in kidney of the 2 quadruple therapy groups were much more than those of the 2 single compound therapy groups (all P < 0.05). The amount of bismuth accumulated in kidney on the cessation day of administration was more than that eight weeks later (both P < 0.01). Under electron microscopy, black-brown granules were observed exclusively in the lysosomes of the proximal convoluted renal tubule cell. Electron microscopy found cell impairment in the quadruple therapy groups. Impairment of these cells could be recovered 8 weeks after the cessation of administration.

CONCLUSION

Acid suppression therapy causes an increase of absorption and accumulation of bismuth from CBP in the kidney. Bismuth can be accumulated in the cell bodies of proximal convoluted renal tubule after its absorption. The absorbed bismuth can be discharged out of the body via kidney. Large amounts of bismuth accumulation in kidney can impair the functions of proximal convoluted renal tubule cells.

On the development of colloidal nanoparticles towards multifunctional structures and their possible use for biological applications

In this Review, we describe the synthesis of high-quality colloidal nanoparticles in organic solvents, the mechanisms by which they can be transferred into aqueous solution, and some of their applications in biology. In particular, we will place emphasis on the creation of multifunctional nanoparticles or nanoparticle assemblies.

Isolation of interstitial fluid from skeletal muscle and subcutis in mice using a wick method

Until recent years, mice were sparsely used in physiological experiments, and therefore, data on the basic cardiovascular parameters of mice are lacking. Our aim was to gain access to interstitial fluid and thereby study transcapillary fluid dynamics in this species. Using a modified wick method, we were able to isolate interstitial fluid from subcutis and skeletal muscle in mice. Three-stranded, dry, nylon wicks were inserted post mortem in an attempt to avoid local inflammation and thus eliminate protein extravasation and wick contamination. Colloid osmotic pressure (COP) was measured with a colloid osmometer for submicroliter samples and averaged (means +/- SE) 18.7 +/- 0.4 in plasma, 9.1 +/- 0.4 in subcutis, and 12.3 +/- 0.5 mmHg in muscle. HPLC of plasma and wick fluid showed similar patterns except for some minor peaks eluting in the <40-kDa region. Plasma protein extravasation as determined by 125I-labeled human serum albumin showed that contamination of wick fluid by plasma proteins was negligible (<2%). Capillary hyperfiltration induced by intravenous infusion of saline (10% of body wt) was reflected in tissue fluid isolated by wicks as shown by the average postinfusion COP values of 14.5 +/- 0.6, 6.8 +/- 0.3, and 7.7 +/- 0.4 mmHg in plasma, subcutis, and muscle, respectively. We conclude that the wick technique can be easily adapted for use in mice and may represent a reliable method to isolate interstitial fluid and study transcapillary fluid flux in this species.

Lipid vesicles and other colloids as drug carriers on the skin

Colloids from an aqueous suspension can cross the skin barrier only through hydrophilic pathways. Various colloids have a different ability to do this by penetrating narrow pores of fixed size in the skin, or the relevant nano-pores in barriers modelling the skin. Such ability is governed by colloid adaptability, which must be high enough to allow penetrant deformation to the size of a pore in such barrier: for a 100 nm colloid trespassing the skin this means at least 5-fold deformation/elongation. (Lipid) Bilayer vesicles are normally more adaptable than the comparably large (lipid coated) fluid droplets. One of the reasons for this, and an essential condition for achieving a high bilayer adaptability and pore penetration, is a high bilayer membrane elasticity. The other reason is the relaxation of changing colloid's volume-to-surface constraint during pore penetration; it stands to reason that such relaxation requires a concurrent, but only transient and local, bilayer permeabilisation. Both these phenomena are reflected in bilayer composition sensitivity, which implies non-linear pressure dependency of the apparent barrier penetrability, for example. Amphipats that acceptably weaken a membrane (surfactants, (co)solvents, such as certain alcohols, etc.) consequently facilitate controlled, local bilayer destabilisation and increase lipid bilayer flexibility. When used in the right quantity, such additives thus lower the energetic expense for elastic bilayer deformation, associated with pore penetration. Another prerequisite for aggregate transport through the skin is the colloid-induced opening of the originally very narrow ( approximately 0.4 nm) gaps between cells in the barrier to pores with diameter above 30 nm. Colloids incapable of enforcing such widening-and simultaneously of self-adapting to the size of 20-30 nm without destruction-are confined to the skin surface. All relatively compact colloids seem to fall in this latter category. This includes mixed lipid micelles, solid (nano)particles, nano-droplets, biphasic vesicles, etc. Such colloids, therefore, merely enter the skin through the rare wide gaps between groups of skin cells near the organ surface. Transdermal drug delivery systems based on corresponding drug formulations, therefore, rely on simple drug diffusion through the skin; the colloid then, at best, can modulate drug transport through the barrier. In contrast, the adaptability-and stability-optimised mixed lipid vesicles (Transfersomes, a trademark of IDEA AG) can trespass much narrower pathways between most cells in the skin; such highly adaptable colloids thus mediate drug transport through the skin. Sufficiently stable ultra-adaptable carriers, therefore, can ensure targeted drug delivery deep below the application site. This has already been shown in numerous preclinical tests and several phase I and phase II clinical studies. Drug delivery by means of highly adaptable drug carriers, moreover, allows highly efficient and well-tolerated drug targeting into the skin proper. Sustained drug release through the skin into systemic blood circulation is another field of ultradeformable drug carrier application.

Quantitative liver-spleen scan using single photon emission computerized tomography (SPECT) for assessment of hepatic function in cirrhotic patients

BACKGROUND/AIMS

Accurate quantitative determination of liver function is critical in cirrhotic patients in order to predict outcome, particularly in patients who undergo hepatic resection or non-hepatic surgery. As colloid uptake by perfused Kupffer cells is proportional to perfused hepatocyte mass, quantitative liver spleen scan may be used as an index of perfused hepatocyte mass. Thus, this study was conducted to evaluate quantitative single photon emission computerized tomography (SPECT) of Tc-99mm-phytate colloid uptake by the liver as a test for hepatic function in cirrhotic patients.

METHODS

Quantitative SPECT was used to measure liver volume, quantitative colloid uptake by the liver and percentage of injected dose/ml of liver tissue in cirrhotic patients (n=75), non-cirrhotic patients with chronic liver disease (n=52) and patients without liver disease (n=36).

RESULTS

Although liver volume was similar among the three groups, the cirrhotic patients had significantly lower total quantitative uptake and quantitative uptake/ml compared to groups 2 and 3 (P<0.001). Quantitative liver uptake in the cirrhotic patients was highly correlated with Child-Pugh score (r=-0.64, P<0.0001) and with indocyanine green retention at 15 min (r=-0.84, P<0.0001).

CONCLUSIONS

Quantitative SPECT of the liver may be an additional, useful, non-invasive quantitative test for assessment of hepatic function and severity of liver disease in cirrhotic patients.

Sentinel lymph node detection with large human serum albumin colloid particles in breast cancer

Detection of metastatic involvement of lymph nodes is essential for management and prognostic evaluation in breast cancer patients. The success of lymphatic mapping depends on identifying the sentinel lymph node(s) draining the primary tumour. However, when mapping is performed with a radiocolloidal agent, the number of hot lymph nodes varies with the agent and its size, among other factors. In this study, we evaluated prospectively the detection rate of sentinel lymph nodes in breast cancer when injecting large particles (100-600 nm) of human serum albumin colloids (Senti-Scint). In 128 consecutive breast cancer patients without palpable lymph nodes, pre-operative static lymphoscintigraphic mapping of the breast was performed after subcutaneous injection of 15 MBq of the radiocolloid. Lymphoscintigrahic results were compared with intra-operative surgical gamma detection probe and blue dye mapping data. Pre-operative lymphoscintigraphy and surgical gamma detection probe both correctly detected 203 sentinel lymph nodes in 122/128 patients (95%), while blue dye mapping showed only 183 sentinel lymph nodes in 82% of the patients. Only one or two sentinel lymph nodes were identified in each patient, which allowed the surgeon easily to find the sentinel lymph node(s) intra-operatively. In conclusion, lymphoscintigraphy with large particles of human serum albumin colloids is a helpful and reliable procedure for the surgical management of breast cancer.

Influence of preparation conditions on acyclovir-loaded poly-d,l-lactic acid nanospheres and effect of PEG coating on ocular drug bioavailability

PURPOSE

The evaluation of nanosphere colloidal suspensions containing acyclovir as potential ophthalmic drug delivery systems was carried out. The influence of polymer molecular weight and type and concentration of various surfactants on nanosphere properties was studied. The ocular pharmacokinetics of acyclovir-loaded nanoparticles was evaluated in vivo and compared with an aqueous suspension of the free drug.

METHODS

Nanospheres were made up of poly-d,l-lactic acid (PLA). The colloidal suspension was obtained by a nanoprecipitation process. The surface properties of PLA nanospheres were changed by the incorporation of pegylated 1,2-distearoyl-3-phosphatidylethanolamine. The mean size and zeta potential of the nanospheres were determined by light scattering analysis. The acyclovir loading capacity and release were also determined. In vivo experiments were carried out on male New Zealand rabbits. The ocular tolerability of PLA nanospheres was evaluated by a modified Draize test. The aqueous humor acyclovir levels were monitored for 6 h to determine the drug's ocular bioavailability for the various formulations.

RESULTS

A reduction of the mean size and a decrease of the absolute zeta potential of PLA nanospheres resulted from increasing the surfactant concentration. The higher the polymer molecular weight, the smaller the nanosphere mean size. PEG-coated and uncoated PLA nanospheres showed a sustained acyclovir release and were highly tolerated by the eye. Both types of PLA nanospheres were able to increase the aqueous levels of acyclovir and to improve the pharmacokinetics profile, but the efficacy of the PEG-coated nanospheres was significantly higher than that of the simple PLA ones.

CONCLUSIONS

PEG-coated PLA nanospheres can be proposed as a potential ophthalmic delivery system for the treatment of ocular viral infections.

Surface-enhanced Raman spectroscopy study on the structure changes of 4-mercaptopyridine adsorbed on silver substrates and silver colloids

Surface-enhanced Raman scattering (SERS) of 4-mercaptopyridine (4-mpy) adsorbed on HNO3 etched silver foil, chemically deposited silver films (silver mirror) and silver colloids were measured. The SERS study has revealed that 4-mpy was adsorbed onto the three kinds of silver surfaces by a sulfur-silver bond with the plane of pyridine ring being normal to the silver substrates. The structure of 4-mpy adsorbed on the silver surfaces depends largely on the pH values of environment. When the pH values of the environment are changed, the structure of 4-mpy adsorbed on silver surfaces can easily be altered through a protonation or deprotonation reaction occurring on the N atom of the pyridine ring, and the modified structure shows unique characters on the SERS spectrum. Owing to the remarkable enhancement ability of SERS technique and characteristic spectrum of different species, a monolayer of 4-mpy assembled on a silver mirror holds potential as a H+ sensor for highly sensitive detection of the proton concentration in an aqueous solution.

Inhibition of Kupffer cell activity induces hepatic triglyceride synthesis in fasted rats, independent of lipopolysaccharide challenge

BACKGROUND

Lipopolysaccharides (LPS), cleared from the blood by Kupffer cells, induce hypertriglyceridemia.

AIMS

To test the hypothesis that GdCl(3), through inhibition of large Kupffer cell activity, modulates LPS-induced hyperlipidemia in rats.

METHODS

Male Wistar rats received a single intravenous injection of GdCl(3)(10 mg/kg) or saline, 24 h before intraperitoneal LPS (1.5 mg/kg) administration. Serum and hepatic lipids as well as activity of key enzymes controlling fatty acid synthesis and esterification in liver tissue were measured. The incorporation of labeled precursors into lipids was assessed in cultured precision-cut liver slices.

RESULTS

GdCl(3) does not prevent hypertriglyceridemia occurring in LPS-treated rats. Surprisingly, GdCl(3) per se is able to promote triglycerides accumulation in the liver tissue, an effect related to an increase in hepatic fatty acid esterification. Such an effect also occurs in rats receiving a dietary supplementation with glycine (5%) known to inhibit Kupffer cell secretory capacity.

CONCLUSIONS

Large Kupffer cell inhibition does not prevent LPS-induced hypertriglyceridemia and even leads to a metabolic shift of fatty acids towards their esterification and accumulation in the liver tissue, suggesting that Kupffer cells play a role in the regulation of lipid metabolism of the adjacent hepatocytes, independent of any inflammatory stimulus.

Flow cytometric assessment of clearance and relapse characteristics in psoriasis vulgaris after treatment with weekly clobetasol lotion under hydrocolloid occlusion versus twice-daily clobetasol ointment

Clearance and relapse characteristics of clobetasol lotion under hydrocolloid occlusion once weekly versus clobetasol ointment twice daily were assessed in a comparative flow cytometric study. Quantitative analysis of markers for epidermal proliferation, differentiation and inflammation was performed on epidermal single cell suspensions prepared from 3-mm punch biopsies taken from 15 patients with psoriasis vulgaris before therapy, at clearance and 6 weeks after clearance. After treatment both therapy regimens resulted in substantial changes of all flow cytometric parameters, but clearance was induced earlier in the corticosteroid under hydrocolloid occlusion-treated group. With respect to the relapse phase no difference was observed between both treatments. Although it is remotely possible that the outcome in the treatment of more extensive psoriatic lesions might be different, the present study suggests that the robust clinical efficacy of the treatment with a topical corticosteroid under hydrocolloid occlusion is not associated with a rebound phenomenon.

Lymphatic mapping of sentinel nodes in early vulvar cancer

OBJECTIVE

The aim of the study was to determine the diagnostic accuracy and feasibility of sentinel lymph node (SLN) detection using a gamma probe in patients suffering from vulvar cancer.

METHODS

From May 1998 to November 2000, 26 patients with early vulvar cancer, planned for local wide excision or vulvectomy including groin dissection, were eligible for the study. Two to 3 h before the planned procedure we injected technetium(99) m-labeled microcolloid intradermally at four locations around the tumor. Dynamic and static images were recorded using a gamma camera. SLN locations were marked on the overlying skin. In the operating theater SLNs were identified at the beginning of the procedure using a handheld gamma-detection probe. After resection of suspected SLNs a standard unilateral or bilateral groin dissection was performed, subsequently followed by local wide excision or, if indicated, radical vulvectomy. Sentinel node detection using technetium(99) m-labeled microcolloid was compared with final histopathological and immunohistochemical results.

RESULTS

Scintigraphy showed focal uptake in all 26 patients. Intraoperatively we detected all sentinel nodes by handheld gamma probe. In 20 patients, one sentinel node was identified unilaterally, while in 6 patients two or more nodes were identified bilaterally. Histologically positive SLNs were found in 9 patients. In our preliminary series we did not find any false-negative SLN.

CONCLUSION

Identification of sentinel nodes in vulvar cancer is feasible with preoperatively administered technetium(99)m-labeled microcolloid. We confirm the results of previous studies and improve the evidence that the SLN procedure could be implemented in future therapy concepts.

Distribution of normal saline and 5% albumin infusions in cardiac surgical patients

OBJECTIVE

To determine the relative distribution of fluid within the extracellular fluid volume (ECFV) and the effect on oxygen delivery after infusing either normal saline or 5% albumin in cardiac surgical patients.

DESIGN

Prospective, randomized, unblinded, interventional study.

SETTING

Cardiac surgical intensive care unit in a 450-bed teaching hospital.

PATIENTS

Postoperative cardiac surgical patients (n = 40).

INTERVENTIONS

Infusion of either normal saline or 5% albumin to a hemodynamic end point determined by the patient's clinician.

MEASUREMENTS AND MAIN RESULTS

Plasma volume (PV), ECFV, cardiac index, and arterial oxygen content were measured immediately before (baseline) and after each fluid infusion. PV and ECFV were measured by dilution of (131)I-albumin and [(35)S]sodium sulfate, respectively. Interstitial fluid volume (ISFV) was calculated as ECFV - PV. Baseline values for PV, ISFV, ECFV, and oxygen delivery index did not differ between treatment groups. Infusion of normal saline and 5% albumin increased PV by 9 +/- 23% and 52 +/- 84% of the volume infused, respectively (p <.05), whereas there was no significant difference between saline and albumin in the change in ISFV per volume infused. Only 5% albumin significantly increased cardiac index, although oxygen delivery did not change significantly after either infusion.

CONCLUSIONS

In postoperative cardiac surgical patients, infusion of 5% albumin is approximately five times as efficient as a PV expander but has comparable effects on changes in ISFV and oxygen delivery relative to normal saline.

Role of genetic algorithms and artificial neural networks in predicting the phase behavior of colloidal delivery systems

PURPOSE

A genetic neural network (GNN) model was developed to predict the phase behavior of microemulsion (ME), lamellar liquid crystal (LC), and coarse emulsion forming systems (W/O EM and O/W EM) depending on the content of separate components in the system and cosurfactant nature.

METHOD

Eight pseudoternary phase triangles, containing ethyl oleate as the oil component and a mixture of two nonionic surfactants and n-alcohol or 1,2-alkanediol as a cosurfactant, were constructed and used for training, testing, and validation purposes. A total of 21 molecular descriptors were calculated for each cosurfactant. A genetic algorithm was used to select important molecular descriptors, and a supervised artificial neural network with two hidden layers was used to correlate selected descriptors and the weight ratio of components in the system with the observed phase behavior.

RESULTS

The results proved the dominant role of the chemical composition, hydrophile-lipophile balance, length of hydrocarbon chain, molecular volume, and hydrocarbon volume of cosurfactant. The best GNN model, with 14 inputs and two hidden layers with 14 and 9 neurons, predicted the phase behavior for a new set of cosurfactants with 82.2% accuracy for ME, 87.5% for LC, 83.3% for the O/W EM, and 91.5% for the W/O EM region.

CONCLUSIONS

This type of methodology can be applied in the evaluation of the cosurfactants for pharmaceutical formulations to minimize experimental effort.

Melphalan monitoring during hyperthermic perfusion of isolated limb for melanoma: pharmacokinetic study and 99mTc-albumin microcolloid technique

BACKGROUND

The kinetics of melphalan leakage from extracorporeal fluid to the peripheral blood was studied in ten patients undergoing hyperthermic isolation perfusion of the lower limbs as an adjuvant treatment in high-risk melanoma.

MATERIALS AND METHODS

Systemic leakage was monitored by a new technique using 99mTc-albumin microcolloid. Serial samples were drawn from a peripheral vein and from the perfusion circuit during surgical treatment and analysed by HPLC.

RESULTS

The leakage measured with 99mTc-albumin microcolloid ranged from 1.5 to 18%/h (mean 8%/h). The average concentrations in the perfusate were 200-300-fold those found in the systemic circulation. A good correlation (R=0.945) was obtained between systemic AUC (0 to 1 hour) and leakage measured through the 99mTc procedure. Negligible toxicity was found and the survival rate yielded 92% of objective response.

CONCLUSION

By studying the pharmacokinetic data of melphalan in the circuit and in the systemic circulation, we were able to validate the 99mTc procedure used during clinical perfusion. Moreover, considering the efficiency of the system as well as the minimum toxicity and the high survival rate, a reduction of perfusion time may be considered.

Locoregional cancer treatment with magnetic drug targeting

The specific delivery of chemotherapeutic agents to their desired targets with a minimum of systemic side effects is an important, ongoing challenge of chemotherapy. One approach, developed in the past to address this problem, is the i.v. injection of magnetic particles [ferrofluids (FFs)] bound to anticancer agents that are then concentrated in the desired area (e.g., the tumor) by an external magnetic field. In the present study, we treated squamous cell carcinoma in rabbits with FFs bound to mitoxantrone (FF-MTX) that was concentrated with a magnetic field. Experimental VX-2 squamous cell carcinoma was implanted in the median portion of the hind limb of New Zealand White rabbits (n = 26). When the tumor had reached a volume of approximately 3500 mm3, FF-MTX was injected intraarterially (i.a.; femoral artery) or i.v. (ear vein), whereas an external magnetic field was focused on the tumor. FF-MTX i.a. application with the external magnetic field resulted in a significant (P < 0.05), complete, and permanent remission of the squamous cell carcinoma compared with the control group (no treatment) and the i.v. FF-MTX group, with no signs of toxicity. The intratumoral accumulation of FFs was visualized both histologically and by magnetic resonance imaging. Thus, our data show that i.a. application of FF-MTX is successful in treating experimental squamous cell carcinoma. This "magnetic drug targeting" offers a unique opportunity to treat malignant tumors locoregionally without systemic toxicity. Furthermore, it may be possible to use these magnetic particles as a "carrier system" for a variety of anticancer agents, e.g., radionuclides, cancer-specific antibodies, and genes.

Interaction of cationic colloids at the surface of J774 cells: a kinetic analysis

We have characterized the binding of multilamellar colloids to J774 cells. Cationic colloids were shown to bind much more efficiently than neutral ones. Particle uptake by cells was followed by flow cytometry and fluorescence microscopy. Analysis of the kinetics of uptake of cationic particles indicated that binding on the cell surface occurred with two characteristic times. Analysis of the dissociation properties allowed discriminating between several alternative models for adsorption and led us to propose a mechanism that involved two independent classes of binding sites on the cell surface. One class of sites appeared to be governed by a classic mass action law describing a binding equilibrium. The other sites were populated irreversibly by particles made of 10% cationic lipids. This was observed in the absence of endocytosis, under conditions where both the equilibrium and the irreversible binding occurred at the cell surface. We determined the rate constants for the different steps. We found that the reversible association occurred with a characteristic time of the order of tens of seconds, whereas the irreversible binding took a hundred times longer. The presence of serum proteins in the incubation medium did not drastically affect the final uptake of the particles. In contrast, the capture of the particles by cells significantly dropped when the fraction of positively charged lipids contained in the colloids was decreased from 10% to 5%. Finally, the results will be discussed within a comprehensive model where cationic particles find labile binding sites in the volume of the pericellular network (glycocalyx and extracellular matrix) and less-accessible irreversible binding sites at the cell membrane itself.

Size- and surface-dependent uptake of colloid particles into the lymphatic system

PURPOSE

To examine the effect of particle size and surface characteristics on colloidal particle uptake from subcutaneous tissue into the lymphatic system.

MATERIALS AND METHODS

Perfluorocarbon emulsion ZY13163 (median particle diameter, 0.08 micron; surfactant, egg yolk phospholipid), ZY13164 (median particle diameter, 0.36 micron; surfactant, egg yolk phospholipid), ZY13199 (0.18 micron, surfactants Tetronic904) and ZY14001 (0.11 micron, surfactant Pluronic L121) were individually injected into the dorsal skin of the hind foot of rabbits. Lymph flow rates and particle concentrations were determined in prenodal lymph fluid after injection, with and without massage of the skin over the injection site.

RESULTS

In the first 24 hours after injection, the decreasing order of colloid flux without massage was as follows: ZY13199 > ZY14001 > ZY13163 > ZY13164. Lymph flow rates, lymph leukocyte concentrations and colloid concentrations increased substantially with mechanical skin massage.

CONCLUSIONS

Transport of colloids into lymphatic vessels depends on particle size and surface characteristics. Without massage, colloids with egg yolk phospholipid exhibit size dependent decrease in uptake into lymphatics, while with massage only a weak correlation with particle size is present.

Transport of colloidal particles in lymphatics and vasculature after subcutaneous injection

This study was designed to determine the transport of subcutaneously injected viral-size colloid particles into the lymph and the vascular system in the hind leg of the dog. Transport of two colloid particles, with average size approximately 1 and 0.41 microm, respectively, and with and without leg rotation, was tested. Leg rotation serves to enhance the lymph flow rates. The right femoral vein, lymph vessel, and left femoral artery were cannulated while the animal was under anesthesia, and samples were collected at regular intervals after subcutaneous injection of the particles at the right knee level. The number of particles in the samples were counted under fluorescence microscopy by using a hemocytometer. With and without leg rotation, both particle sets were rapidly taken up into the venous blood and into the lymph fluid. The number of particles carried away from the injection site within the first 5 min was <5% of the injected pool. Particles were also seen in arterial blood samples; this suggests reflow and a prolonged residence time in the blood. These results show that particles the size of viruses are rapidly taken up into the lymphatics and blood vessels after subcutaneous deposition.

Distribution of normal saline and 5% albumin infusions in septic patients

OBJECTIVE

To determine the relative distribution of fluid within the extracellular fluid volume (ECFV) after infusing either normal saline or 5% albumin in septic, critically ill patients.

DESIGN

Prospective, randomized, unblinded, interventional study.

SETTING

Intensive care unit in a 450-bed, tertiary care, teaching hospital.

PATIENTS

Septic, critically ill patients (n = 18).

INTERVENTIONS

Infusion of either normal saline or 5% albumin to a hemodynamic end point determined by the patient's clinician.

MEASUREMENTS AND MAIN RESULTS

Plasma volume (PV), ECFV, cardiac index, and arterial oxygen content were measured immediately before (baseline) and after each fluid infusion. PV and ECFV were measured by dilution of 131I-albumin and 35S sodium sulfate, respectively. Interstitial fluid volume (ISFV) was calculated as ECFV - PV. Baseline values for PV, ISFV, ECFV, and oxygen delivery index did not differ between treatment groups. Infusion of normal saline increased the ECFV by approximately the volume infused, and the expansion of the PV to ISFV was in a ratio of 1:3. Infusion of 5% albumin increased the ECFV by double the volume infused, with both the PV and ISFV expanding by approximately equal amounts. Oxygen delivery index did not increase after either infusion due to the effect of hemodilution.

CONCLUSION

Expansion of the ECFV in excess of the volume of 5% albumin infused suggests that fluid may move from the intracellular fluid volume to the ECFV in septic patients who receive this fluid.

[Excessive tissue storage of colloids in the reticuloendothelial system]

In addition to renal elimination and gastrointestinal metabolism (amylase; splenic and hepatic dextranase) colloid plasma solutions like dextran and hydroxyethyl starch deposit in tissues, especially in the reticuloendothelial system (RES). This tissue storage is limited in time (weeks to months), is influenced by the employed solution and other factors (lysosomes) and has usually no clinical importance (no RES blockade). We report here a case study of a patient with sepsis (lung, liver and kidney failure) who had an overload of the RES with colloids while being treated with dextran (molecular weight 40,000 and 70,000 daltons) and hydroxyethyl starch (mw 450,000 daltons, molar substitution 0,7) for 5 weeks. Autopsy showed parenchymal and reticuloendothelial cells of liver, lung, kidney and spleen with a large amount of colloid mass inclusions and altered organ morphology. This storage may have impaired ventilation, transport of bile acids and renal function. A possible role of tissue storage of colloids in organ failure is discussed.

The pharmacokinetics of acetyl starch as a plasma volume expander in patients undergoing elective surgery

Acetyl starch (ACS) is a new synthetic colloid solution for plasma volume expansion and is now undergoing phase 2 clinical trials. We compared the pharmacokinetics of ACS with those of hydroxyethyl starch (HES) in 32 patients (ASA physical status I and II) undergoing elective surgery. In this randomized, double-blind trial, patients received either 15 mL/kg ACS 6% (average molecular weight [Mw] 200,000/molar substitution [MS] 0.5) or HES 6% (Mw 200,000/MS 0.5) i.v. up to a maximal dose of 1000 mL. Plasma colloid concentrations were measured by repetitive arterial blood sampling over 24.5 h. Plasma colloid concentrations were detected using a high-pressure liquid chromatography controlled enzymatic test. Standard pharmacokinetics were calculated, including initial half-life (t(1/2init)), i.e., the time required for a 50% decline of the maximal plasma colloid concentration at the end of drug infusion. Whereas HES was eliminated by second-order kinetics, ACS followed first-order characteristics. In the first hours after i.v. administration, t(1/2init) and clearances were similar in both groups. However, the terminal half-life of HES was significantly longer than that of ACS (9.29 +/- 1.43 h vs 4.37 +/- 1.06 h). After 16.5 and 24.5 h, ACS showed significantly lower plasma concentrations than HES, which indicates that the final degradation of ACS by esterases and amylase was significantly more rapid. ACS might be an alternative plasma volume expander, which avoids the accumulation of persisting macromolecules.

IMPLICATIONS

We studied the pharmacokinetics of acetyl starch, a newly developed colloid solution for plasma volume substitution, compared with hydroxyethyl starch in 32 surgical patients undergoing elective major general surgical procedures. In contrast to hydroxyethyl starch, this new agent undergoes rapid and nearly complete enzymatic degradation.

The effect of lymphatic oedema on the uptake of colloids to the lymph nodes

The majority of pathological conditions of the lymphatic system can result in some degree of lymphoedema, which in turn causes a reduced rate of lymph flow. In some cases, such as when nodes are invaded by tumour metastases, blockage of the lymphatic vessels may occur. In order to investigate the effect of such pathology on nanosphere uptake in regional lymph nodes, the fate of model polystyrene nanospheres, surface modified with block co-polymers of the poloxamine series, was determined following subcutaneous administration in a rat model with lymphoedema (induced by the administration of lambda-carrageenan). A drastic reduction of injection site drainage and lymph node uptake of nanospheres was observed in the inflammation model compared to control animals. The observations suggest that biodegradable nanospheres based on these will be suitable for the detection of oedema in the lymphatic system.

The use of colloids in clinical practice

The use of colloid solutions for fluid resuscitation in hypovolaemic patients is widespread in clinical practice. This article describes the types of colloid agents which are currently available, their physicochemical properties, and adverse effects which may follow their administration. The relative merits of colloids compared with crystalloid solutions are discussed.

Passage of peptides through the blood-brain barrier with colloidal polymer particles (nanoparticles)

Transport of the hexapeptide dalargin across the blood-brain barrier was accomplished using a nanoparticle formulation. The formulation consisted of dalargin bound to poly(butyl cyanoacrylate) nanoparticles by sorption, coated with polysorbate 80. Intravenous injection of this formulation to mice resulted in an analgesic effect. All controls, including a simple mixture of the three components (drugs, nanoparticles, and surfactant) mixed directly before i.v. injection, exhibited no effect. Analgesia was also prevented by pretreatment with naloxone. Fluorescent and electron microscopic studies indicated that the passage of the particle-bound drug occurred by phagocytic uptake of the polysorbate 80-coated nanoparticles by the brain blood vessel endothelial cells.

A lymphotropic colloidal carrier system for diethylcarbamazine: preparation and performance evaluation

Targeting to organs other than the RES-bearing organs is difficult to achieve. A nanoparticle-based emulsion delivery system was prepared and its efficacy in enhancing the lymphatic uptake of the anti-filarial drug diethylcarbamazine was evaluated. It was compared with a simple w/o emulsion and a control aqueous solution. The effect of route of administration on the lymphatic uptake was studied and it was found that the i.p. route gave better results as compared to the i.v. route, in which total lack of lymphatic uptake was observed. The nanoparticle-in-oil emulsion system holds excellent potential as a lymphotropic carrier system.

Pharmacology of colloids and crystalloids

We have attempted to review body fluid distribution by compartments so that the reader understands the physiology of ICF and ECF, and the relationship between interstitial and intravascular fluids. Crystalloids such as NS and RL are distributed to the ECF, whereas colloids primarily remain intravascular for longer periods. Although effective, crystalloids tend to require larger volumes for infusion, and edema remains a problem. Colloids as a group are extremely effective volume expanders, but none is ideal. Albumin, hetastarch, dextran, and the less commonly used colloids each have significant toxicities that must be considered when using them. Intelligent choices can be made to optimize use of these fluids.

Asymmetrical effects of albumin on transsynovial fluid movement

The effect of intraarticular infusions of albumin solution on transsynovial flow was studied in healthy rabbit knee joints and compared with the effect of albumin solution perfused through the synovial microcirculation. Increasing intravascular albumin levels enhanced fluid absorption from the joint cavity, whereas increasing intraarticular albumin levels reduced the absorption rate. The slope of intraarticular pressure-versus-absorption rate plots was reduced by albumin in proportion to the reduction in fluidity (1/viscosity). When joint pressure was held constant, the transsynovial absorption rate was reduced by albumin in excess of the fluidity reduction and even reversed to filtration into the joint cavity. Thus intraarticular albumin acts by a dual mechanism, namely by increasing synovial interstitial fluid viscosity and by exerting a peri-capillary oncotic pressure. However, the latter effect was much less than that of intravascular albumin. Reasons for this are discussed.

Constant potassium chloride release from microporous membrane-coated tablets prepared with aqueous colloidal polymer dispersions

To achieve constant drug release and to avoid the use of organic solvents, potassium chloride tablets were coated with aqueous latexes containing dispersed pore-formers with pH-dependent solubility characteristics. The pore-forming agent, dibasic calcium phosphate, was insoluble in the latex but soluble at low pH. Upon contact with simulated gastric fluids, it leached out rapidly to form a rate-controlling, microporous membrane. The release of potassium chloride was linear with time up to 75-80% drug released. It increased with increasing level of pore-former and decreasing membrane thickness but was independent of the degree of agitation and the pH of the dissolution medium after leaching of the pigments. Upon storage at different relative humidities, moisture uptake of the film coat and variations in the release profiles over time were minimal.

[Fundamental study of 99mTc nanocolloids for inflammation imaging]

The biodistribution of nanometer-sized colloidal particles (nanocolloids, Solco-Basle Ltd.) was examined in six rabbits with turpentine-induced abscesses in the musculature of their hind legs. 99mTc labelled colloids with a mean particle size less than 100 nm were administered to each rabbit intravenously. The biodistribution of the tracer was studied with a gamma camera 1, 3, and 24 hours after injection. Prominent uptakes were demonstrated in the liver, spleen, bone marrow, kidneys, and urinary bladder. On the other hand, the abscess and surrounding inflammatory edema were depicted as unclearly margined faint hot spots. Subsequently, the rabbits were sacrificed and activity per gram tissues were counted with a well-type gamma counter. Although the results were almost in agreement with a gamma camera study, it was noticed the activity counts in the abscess were significantly higher than that of control muscles.

Regeneration and phagocytic function of devascularized spleens

The phagocytic function of normal splenic tissue and of regenerated tissue following splenic artery ligation was investigated in rats using radiolabelled stannous fluoride colloid. Colloidal carbon was used to determine the histological location of phagocytosis within the spleen. Six months after ligation, the median weight of the devascularized spleens was 25% of that of spleens in control rats. Technetium stannous colloid clearance by devascularized spleens was reduced to 10% of normal and 25% when corrected for spleen weight. The colloidal carbon injected intravenously was observed primarily in the marginal zone in both normal and devascularized spleens. Histologically, devascularized spleens contained significantly less white pulp and marginal zone. The splenic tissue which regenerates following ligation does not have the phagocytic ability of normal splenic tissue. This may be due to the decreased regrowth of the lymphoid compartments of the spleen.

[Differential correction of disorders of colloid-oncotic blood pressure in pregnant women and puerperants with suppurative-septic diseases]

The measurement of colloid-oncotic pressure (COP) in 160 women with pyoseptic disease (pyodermia, soft-tissue abscesses, suppurative mastitis, endometritis, sepsis) has demonstrated a regular pattern of change, depending on the clinical condition. A classification of COP disorders has been proposed, identifying the hyperoncotic state (COP above 3.29 kPa), normoncotic state (COP between 2.84 and 3.29 kPa) and hypo-oncotic state (COP below 2.84 kPa), on which a differential remedial therapy is based. A reliable assessment of COP values during the infusion therapy can only be made by means of oncometry, since estimations of any kind lead to considerable error.