Effects of food on plasma catecholamine and gastrin levels in patients with duodenal ulcer and normal volunteers

The expression of sugar residues on human epidermal cells was investigated by means of lectin binding, as a way of determining membrane structural changes occurring during the differentiation of the epidermis. Fourteen lectins of different sugar specificity were conjugated with fluorescein isothiocyanate (FITC-lectins) and tested in fluorescence microscopy on frozen sections of normal human epidermis. In parallel, FITC-lectins were tested on psoriatic-involved epidermis to visualize differences in the expression of sugar residues that might occur during abnormal epidermal differentiation. No labelling could be obtained with lectins from Bandeira simplicifolia I, Dolichos biflorus, Limulus poyphemus, Tetragonolobus purpureas, Ulex europeus I, and Triticum vulgaris (group 1 lectins). A "pemphigus-like" intercellular labelling of the whole epidermis, except the stratum corneum, was obtained with lectins from Canavalia ensiformis. Maclura pomifera, Phaseolus vulgaris, and Ricinus communis I (group 2 lectins). A selective intercellular labelling of the stratum spinosum and the stratum granulosum was seen in normal epidermis with lectins from Arachis hypogaea, Glycine max, Helix pomatia, and Sophora japonica (group 3 lectins). In psoriatic epidermis, not only the basal cell layer, but also cells from the adjacent lower stratum spinosum were found to be negative, using FITC-lectins of group 3. These data indicate that the expression of lectin binding sites in normal epidermis differs according to the maturation of the cell from the basal cell to the more mature keratinocyte in the stratum granulosum. They suggest that lectins may be used as markers of epidermal cells in various stages of normal and abnormal differentiation.     

Determination of DNA damage in F344 rats induced by geometric isomers of tamoxifen and analogues

The transformation of Trypanosoma cruzi epimastigotes to mammal-infective metacyclic trypomastigotes (metacyclogenesis) can be performed in vitro under chemically defined conditions (TAU 3AAG medium). During this process, changes in the nature of cell surface sugar composition and sugar distribution was evaluated using FITC and gold-labeled lectins and observed by flow cytometry and transmission electron microscopy. The pattern of labeling with the lectins from Triticum vulgaris (WGA), Arachis hypogaea (PNA), Limax flavus (LFA), Canavalia ensiformis (Con-A), and Ricinus communis (RCA-I) significantly changed during the metacyclogenic process. The results obtained are discussed in relation to the role played by T. cruzi cell surface carbohydrate residues on the process of parasite-host cell interaction.     

Electroencephalographic changes in experimental autoimmune myasthenia gravis

A procedure for the determination of activity and linkage specificity of sialidases is described. The sialoglycoprotein fetuin is coated onto a microtiter plate and incubated with sialidases from different sources. Enzymatic activities and linkage specificities are then determined by a sandwich method which measured the binding of different lectins to fetuin. The lectins used were peanut agglutinin (PNA) from Arachis hypogaea, which binds specifically the galactose beta-1-3-N-acetylgalactosamine structures that are unmasked following sialidase treatment of fetuin, the lectins from Sambucus nigra (SNA) and Maackia amurensis (MAA) that are specific for alpha-2-6 and alpha-2-3 bound sialic acids, respectively, and the slug agglutinin from Limax flavus (LFA) that is specific for N-acetyl and N-glycolyl neuraminic acids. Increased PNA and decreased LFA, SNA, and MAA lectin binding correlated with sialidase-induced desialylation of the substrate. In this report, the assay was used to determine the activities and specificities of influenza, Vibrio cholerae, and Arthrobacter ureafaciens sialidases.     

Age-related increase in an advanced glycation end product in penile tissue

Nonenzymatic glycosylation (glycation) of proteins, often referred to as the Maillard reaction, has been proposed to play a role in age and diabetes-related processes by forming protein and DNA adducts and cross-links. These cross-links may contribute to erectile dysfunction by scavenging nitric oxide, which is needed for erection. As the basis for a possible role of the advanced Maillard reaction in age-related erectile dysfunction, we investigated the presence of the specific advanced glycation endproduct (AGE) pentosidine in penile corpus cavernosum tissue and penile tunica albuginea tissue as a function of age. A total of 23 penile tissue specimens were obtained at autopsy, from which 19 samples of tunica albuginea and 21 samples of corpus cavernosum were derived. In addition, 13 penile corporal and tunical specimens were procured at the time of insertion of a penile prosthesis, from which 12 tunica albugineal specimens and 10 samples of corpus cavernosum were derived. Collagen was extracted with acetic acid and pepsin digestion, and the final insoluble collagen product was acid-hydrolyzed with 6 N HCL for 24 h at 110 degrees C. Pentosidine was quantified by high-performance liquid chromatography using a reverse-phase column. The level of pentosidine (expressed in picomoles per milligram of insoluble collagen) was found to increase with age in cadaver as well as living penile corporal and tunical albugineal tissues. Best-fit analysis revealed an exponential increase in both types of cadaver penile tissue, with regression equations of y = 15.29 x 10(9.9e-3x), R2 = 0.79, being obtained in the tunica and y = 13.2 x 10(7.63e-3x), R2 = 0.56, in the corpora. These correspond to 6- and 4-fold increases in pentosidine levels from puberty to the age of 100 years (P < 0.05), respectively. Mean pentosidine levels were higher in the tunica than in the corpora. Comparison of pentosidine levels in the tunica versus the corpora revealed a weakly linear correlation (y = 24.88 + 1.08x, R2 = 0.32). Levels in the tunical and corporal specimens from the living human specimens fell with the predicted confidence intervals of the cadaveric tissue. Tunical specimens from patients who underwent repair or revision of a previously inserted penile prosthesis had very low levels of pentosidine. The exponential age-related increase in pentosidine observed in both types of penile tissue suggests an impairment of collagen turnover, which could be related to the advanced glycation reaction in aging. It is not known whether pentosidine itself is directly associated with erectile dysfunction, but its formation is usually accompanied by extensive tissue modification. Formation of advanced Maillard reaction products, which is greatly accelerated in aging, diabetes, and uremia, could contribute to erectile dysfunction in these syndromes.     

Synthesis of artificial N-glycopolypeptides carrying N-acetyllactosamine and related compounds and their specific interactions with lectins

Artificial N-glycopolypeptides carrying N-acetyllactosamine (LacNAc) or related compounds were synthesized. First, sugars were converted into their corresponding beta-glycosylamines with ammonium hydrogen carbonate. Then, the beta-glycosylamines were condensated with the carboxyl groups of poly(L-glutamic acid). N-Glycopolypeptides with different degrees of substitution of sugars were isolated by passage through a column of Sephadex G-25. These synthetic polymers were used as model compounds in the analysis of oligosaccharide-lectin interactions. Interactions with some lectins were investigated by agar-gel double-diffusion tests and in terms of inhibition of hemagglutination. A glycopolypeptide substituted with LacNAc reacted with Erythrina cristagalli agglutinin (ECA), peanut (Arachis hypogaea) agglutinin (PNA), Ricinus communis agglutinin-120 (RCA120), wheat germ (Triticum vulgaris) agglutinin (WGA) lectins, which recognize either galactosyl or N-acetylglucosamine (GlcNAc) residues. Other synthetic glycopolymers carrying N-acetylisolactosamine, GlcNAc, N,N'-diacetylchitobiose, or N,N', N"-triacetylchitotriose also reacted with WGA, and these last two polymers inhibited hemagglutination most. Of these five glycopolypeptides, only the one substituted with LacNAc reacted with ECA. These sugar-substituted glycopolypeptides interacted specifically with the corresponding lectins, no matter how much shorter the sugar side chains of the glycopolymers were than those of natural glycoproteins.     

The anatomy of the tunica albuginea in the normal penis and Peyronie's disease

PURPOSE: We studied the fine architecture of the tunica albuginea of the penis. MATERIALS AND METHODS: The study included 6 human male cadavers and 10 surgical patients (5 with Peyronie's disease and 5 with normal penile anatomy). RESULTS: The tunica albuginea of the corpora cavernosa is a bi-layered structure with multiple sub layers. Inner layer bundles support and contain the cavernous tissue and are oriented circularly. Radiating from this layer are intracavernous pillars acting as struts, which augment the septum and provide essential support to the erectile tissue. Outer layer bundles are oriented longitudinally. These fibers extend from the glans penis to the proximal crura, where they insert into the inferior pubic ramus. There are no outer layer fibers between the 5 and 7 o'clock positions. Elastic fibers normally form an irregularly latticed network on which collagen fibers rest. In Peyronie's disease the well ordered appearance of the collagen layers is lost: excessive deposits of collagen, disordered elastic fibers and fibrin are found within the region of the plaque. CONCLUSIONS: The normal 3-dimensional structure of the tunica affords great flexibility, rigidity and tissue strength to the penis, which are lost consequent to structural changes in Peyronie's disease.     

Glycosylation patterns of membrane proteins of the jellyfish Cyanea capillata

Integral and membrane-associated proteins extracted from neuron-enriched perirhopalial tissue of the jellyfish Cyanea capillata were probed with a panel of lectins that recognize sugar epitopes of varying complexity. Of the 13 lectins tested, only concanavalin A, jacalin lectin and tomato lectin stained distinct bands on Western blots, indicating the presence of repeating alpha-1,6-mannoses, terminal Gal-alpha-1,6-GalNAc and repeating beta-1,4-linked GlcNAc, respectively. In whole-mounted perirhopalial tissue, jacalin lectin stained several cell types, including neurons, muscle, cilia and mucus strands. Tomato lectin stained secretory cells intensely, and neurons in a punctate fashion. Concanavalin A stained cytoplasmic epitopes in both ecto- and endodermal cells, and ectodermal secretory cells and the mucus strands emanating from them. With the exception of tomato lectin's sugar epitope, the other sugar epitopes identified in this study are "non-complex". This study suggests that while glycosylation of integral and membrane-associated proteins occurs in Cyanea, the sugars post-translationally linked to these proteins tend to be simple.     

Characteristics of the histamine release from hamster cheek pouch mast cells stimulated by lectins from Brazilian beans and concanavalin A

We have characterized the histamine releasing effects of lectins extracted from Brazilian beans, in comparison to concanavalin A, in hamster cheek pouch cell suspensions containing mast cells. The lectins from Dioclea virgata, Canavalia brasiliensis, and Dioclea rostrata induce histamine release in a similar manner to concanavalin A, but appear to differ in potency and efficacy. The effects depended on the temperature, pH, and metabolic energy, demonstrating the non-cytotoxic nature of the histamine release. It is suggested that the lectins studied act by the same mechanism as concanavalin A (interacting with sugars in the antibodies bound to the mast cells), since high concentrations of glucose inhibit the histamine release. The lectins at high concentrations quench the histamine release. This suppression is reversed by increasing calcium concentration, suggesting that the lectins bind to the calcium that is essential for the secretion, thereby confirming and extending our previous data using the lectin from Dioclea virgata in rat peritoneal mast cells.     

Susceptibility of heterozygous MnSOD gene-knockout mice to oxygen toxicity

OBJECTIVE: To study type IV collagen of skin and serum in patients with ALS. BACKGROUND: Collagen abnormalities of skin have been reported in ALS patients. However, little is known concerning type IV collagen in ALS. METHODS: We studied type IV collagen immunoreactivity of skin and measured serum levels of the 7S fragment of the N-terminal domain of type IV collagen (7S collagen) in patients with ALS and control subjects. RESULTS: The basement membrane as well as blood vessels of skin in ALS patients was weakly positive for type IV collagen as compared with those of diseased control subjects. This weak immunostaining became more pronounced as ALS progressed. The optical density for type IV collagen immunoreactivity in ALS patients was significantly lower (p < 0.001) than in diseased control subjects and was significantly decreased with duration of illness (r = -0.85, p < 0.01). Serum 7S collagen levels in patients with ALS were significantly decreased (p < 0.01) as compared with those in diseased and healthy control subjects and were negatively and significantly associated with duration of illness (r = -0.81, p < 0.001). There was an appreciable positive correlation between concentrations of serum 7S collagen and the density for type IV collagen immunoreactivity in ALS patients (r = 0.81, p < 0.02). CONCLUSIONS: These data suggest that a metabolic alteration of type IV collagen may take place in the skin of ALS patients and that the decreased levels of serum 7S collagen may reflect a decreased type IV collagen immunoreactivity of skin in patients with ALS.     

Studies on 6C3HED murine ascites tumor cell receptors for mannosyl-binding lectins

We have investigated the receptor site activity present on 6C3HED tumor cells for concanavalin A, fava, lentil and pea lectins. The binding of the tritiated lectins to the tumor cells was inhibited by methyl-alpha-D-mannoside but not by D-galactose. The number of binding sites for the lectins was 3.5-10(6)/cell for concanavalin A, 3.3-10(6)/cell for fava, 3.6-10(6)/cell for lentil and 4.8-10(6)/cell for pea. The apparent association constants were 3.6 and 1.3 muM-1 for concanavalin A, 3.9 muM-1 for fava, 4.2 muM-1 for lentil and 4.6 and 0.6 muM-1 for pea. Competitive inhibition studies showed that lentil was a good inhibitor of pea binding; concanavalin A was a poor inhibitor of pea binding; and fava was a better inhibitor than concanavalin A but not as good as lentil. Reciprocal inhibition experiments indicated that concanavalin A and pea may bind to different receptors as well as to common receptors. This was also indicated by the observation that trypsin or protease treatment of the cells decreased the binding of pea lectin by 20-40 percent whereas concanavalin A binding was unaffected.     

Immunohistochemical study of collagen in gastric cancer tissue

The distribution and localization of collagen types were studied immunohistochemically in resected tissues obtained from gastric cancer patients. The expression of transforming growth factor (TGF) -alpha, TGF-beta 1 and TGF-beta 2 on cancer cells as well as the aggregation of T lymphocytes in the cancer tissue were also studied, in order to determine the differences between differentiated and undifferentiated type cancer. The interstitial tissues of differentiated type cancer showed intense staining for types I and III collagen, while those of undifferentiated type cancer showed intense staining for types I and III collagen, in addition to the stronger staining for types IV, V and VI collagen. Characteristically, type IV collagen was intensely stained in the interstitium in 18 of 20 undifferentiated type cancer (90%), but was stained in only one of 15 differentiated type cancer (6%). CD 3+ T lymphocytes were aggregated in the interstitial tissue of both the tumors, where the density of CD 4+ cells and the ratio of CD 4 to CD 8 were significantly higher in undifferentiated type cancer than in differentiated type cancer. TGF-alpha was detected in cancer cells in 80% of the differentiated cases and in 45% of the undifferentiated cases. The staining of TGF-beta 1 was also detected in 80% of the undifferentiated cases, which was significantly higher than 47% in differentiated cases. There were no differences in the incidences of staining for TGF-beta 2 between differentiated (33%) and undifferentiated type cancer (40%). These results suggest that there exist different mechanisms in the regulation of collagen production between differentiated and undifferentiated types of gastric cancer.     

Analysis of carbohydrate structures in basal laminar deposit in aging human maculae

PURPOSE: To analyze carbohydrate structures in basal laminar deposit (BLD), an extracellular material that accumulates between the retinal pigment epithelium (RPE) and Bruch's membrane. BLD has been shown to correlate positively with visual loss in age-related macular degeneration. METHODS: Thirteen postmortem human maculae with BLD were histochemically examined by light microscopy using the monoclonal antibody HNK-1 and seven lectins; canavalia ensiformis (ConA), soybean agglutinin (SBA), wheat germ agglutinin (WGA), dolichos bifloris (DBA), ulex europaeus (UEA-I), ricinius communis agglutinin I (RCA-I), and peanut agglutinin (PNA). Three maculae were stained with polyclonal antibodies against laminin and collagen type IV. RESULTS: BLD was exclusively stained by DBA and SBA, whereas Con A, WGA, UEA-I, RCA-I, and HNK-1 stained various other structures in the human macula as well. The main part of the BLD adjacent to Bruch's membrane stained with these lectins and the monoclonal antibody HNK-1, whereas only a small part of the BLD adjoining the RPE stained with antibodies against laminin and collagen type IV. Drusen stained neither with any lectin nor with any antibody. CONCLUSIONS: DBA and SBA, which bind specifically to an alpha-D-GalNAc moiety, are specific markers for the light-microscopic detection of BLD in human macular tissue. Furthermore, the authors conclude that BLD contains several carbohydrate structures other than the carbohydrate moieties on laminin and collagen type IV. If drusen contain carbohydrate structures, these must be different from those in BLD.     

Lectin binding to dissociated cells from two species of Xenopus embryos

1. Fluorescein isothiocyanate-conjugated concanavalin A (F-conA) and soy bean agglutinin (F-SBA) bind to the surface of EDTA-dissociated cells from blastula and gastrula stage Xenopus laevis and X. mulleri embryos. 2. Binding of these lectins is abolished by appropriate haptens (alpha-methyl-D-mannopyranoside for F-conA and 2-acetamido-2-deoxy-D-galactose for F-sba). 3. Gastrula stage cells show a clustering or capping of lectin binding sites not shown by blastula stage cells. 4. At least for F-conA, this capping is induced by the lectin. 5. There are no striking regional differences in either amount or pattern of lectin binding in early gastrulae of both species.     

Diocleinae lectins are a group of proteins with conserved binding sites for the core trimannoside of asparagine-linked oligosaccharides and differential specificities for complex carbohydrates

The seed lectin from Dioclea grandiflora and jack bean lectin concanavalin A (ConA) are both members of the Diocleinae subtribe of Leguminosae lectins. Both lectins have recently been shown to possess enhanced affinities and extended binding sites for the trisaccharide, 3,6-di-O-(alpha-D-mannopyranosyl)-D-mannose, which is present in the core region of all asparagine-linked carbohydrates (Gupta, D., Oscarson, S., Raju, S., Stanley, P. Toone, E. J. and Brewer, C. F. (1996) Eur. J. Biochem. 242, 320-326). In the present study, the binding specificities of seven other lectins from the Diocleinae subtribe have been investigated by hemagglutination inhibition and isothermal titration microcalorimetry (ITC). The lectins are from Canavalia brasiliensis, Canavalia bonariensis, Cratylia floribunda, Dioclea rostrata, Dioclea virgata, Dioclea violacea, and Dioclea guianensis. Hemagglutination inhibition and ITC experiments show that all seven lectins are Man/Glc-specific and have high affinities for the core trimannoside, like ConA and D. grandiflora lectin. All seven lectins also exhibit the same pattern of binding to a series of monodeoxy analogs and a tetradeoxy analog of the trimannoside, similar to that of ConA and D. grandiflora lectin. However, C. bonariensis, C. floribunda, D. rostrata, and D. violacea, like D. grandiflora, show substantially reduced affinities for a biantennary complex carbohydrate with terminal GlcNAc residues, while C. brasiliensis, D. guianensis, and D. virgata, like ConA, exhibit affinities for the oligosaccharide comparable with that of the trimannoside. Thermodynamic data obtained by ITC indicate different energetic mechanisms of binding of the above two groups of lectins to the complex carbohydrate. The ability of the lectins to induce histamine release from rat peritoneal mast cells is shown to correlate with the relative affinities of the proteins for the biantennary carbohydrate.     

Comparison of tunica albuginea substitutes for the treatment of Peyronie's disease

PURPOSE: Peyronie's disease is a connective tissue disorder resulting in fibrotic plaque formation on the tunica albuginea of the penis. One approach to repair consists of plaque excision and patching with one of many potential patch materials. Because the optimal patch material for covering the resultant defect has not been determined, this study compares histological and cavernosometric changes in the penis as a result of the placement of three different types of patch grafts used in surgery for Peyronie's disease. MATERIALS AND METHODS: Eleven mongrel dogs were divided into three groups, each receiving a different patch material (superficial dorsal penile vein, silicone fabric, and dermabraded preputial flap). Each dog had dynamic infusion cavernosometry (DIC) performed prior to placement of the patch over a 6 x 3 mm. defect surgically created in the tunica albuginea. Three months later, DIC was repeated prior to sacrifice. Histology of the penis was examined using Masson's trichrome, and hematoxylin and eosin stains. RESULTS: The only difference among the cavernosometric parameters (preop versus postop) was a higher initial pressure in the dermabraded preputial flap group postoperatively. The dogs undergoing vein patch had moderate fibrosis with apparent reformation of the tunica albuginea over the patch site. The normal venous architecture of the graft was no longer recognizable. Those dogs receiving a silicone patch had moderate fibrosis with a fibrous sheath of compressed histiocytes and fibroblasts enveloping the graft site. Finally, the dermabraded preputial flap patch group had mild-moderate fibrosis with focal loss of the cavernosal space underlying the flap. CONCLUSIONS: We feel that continued use of the vein patch for repair of Peyronie's disease is warranted.     

Identification and molecular characterization of beta-hemolytic streptococci isolated from harbor porpoises (Phocoena phocoena) of the North and Baltic Seas

The present study was designed to identify and comparatively investigate 35 beta-hemolytic streptococci isolated from stranded harbor porpoises or from animals caught in fishing nets of the North and Baltic seas. According to biochemical and serological data and to lectin agglutination tests with the lectin of Arachis hypogaea, all 35 isolates could be classified in Lancefield's serological group L and could be identified as Streptococcus dysgalactiae subsp. dysgalactiae. All 35 group L streptococci were uniformly sensitive to most of the antibiotics tested. To further analyze the epidemiological relationship, the isolates were subjected to macrorestriction analysis of their chromosomal DNA by pulsed-field gel electrophoresis. Digestion of the chromosomal DNA with the restriction enzymes SmaI and ApaI revealed that most of the group L streptococci seemed to be apparently identical or related. These results indicate that one clone or at least related group L streptococcal clones play an important role for infections of harbor porpoises of the North and Baltic seas. This might possibly be caused by a direct transfer of the bacteria from animal to animal.     

Pigmented uveal tumours in a transgenic mouse model

Lectins are sensitive probes which bind carbohydrate structures specifically. In this study, we modified the lectin staining procedure for sensitive detection of carbohydrate structures in formalin-fixed, paraffin-embedded sections of normal and heterologous serum-induced fibrotic livers. The liver sections were heated in hot distilled water at 100 degrees C for 10 min (thermo-treatment: TT), and then stained with 24 different lectins. In comparison with the results from sections without TT (nonTT), enhanced and/or alternated staining patterns of 19 lectins were demonstrated in sections with TT, and enhanced staining of Vicia villosa agglutinin seen in Kupffer cells was noted. Interestingly, no positive staining was seen with Dolichos biflorus agglutinin, peanut agglutinin or soybean agglutinin (SBA), which recognize O-linked carbohydrate chains, in Kupffer cells of non-TT sections, but strong positive staining was demonstrated in those of TT sections. SBA-positive staining in the cytoplasm of some scattered hepatocytes located in the periportal and perifibrous zones and central zone of pseudolobules was demonstrated only in the fibrotic liver sections with TT. Such findings indicate the heterogeneity of hepatocytes in the liver with fibrosis. Formalin fixation causes masking of lectin binding sites, especially O-linked carbohydrate chains, and TT may recover such masking reactions. TT improved the staining reactions for many lectins in formalin-fixed, paraffin-embedded liver sections, and new staining patterns appear after TT. Modified TT staining procedures may be useful for the diagnosis and prognosis of liver fibrosis.     

Temporal trends in Canadian birth defects birth prevalences, 1979-1993

Syrian hamsters of the APA strain (APA hamsters) develop spontaneous mesangial thickening in the renal glomeruli from an early age. They also develop focal and segmental glomerulosclerosis (FSG) at and after 6 months of age. In this study, histopathological, immunohistochemical and lectin histochemical examinations were conducted to clarify the modification of the spontaneous renal lesions of APA hamsters by streptozotocin(SZ)-induced diabetes. Histopathological analysis revealed that the expansion of the mesangial region was more prominent and the thickening of the glomerular basement membrane (GBM) was weaker in SZ-treated animals than in non-treated ones. Immunohistochemical analysis suggested that type IV collagen and laminin were involved in the expansion of the mesangial region and thickening of the GBM. In lectin histochemical analysis, podocytes, capillary endothelial cells, GBM and a part of mesangial region of SZ-treated animals were positive for RCA120 and GSL-I with neuraminidase-pretreatment although they were negative for these lectins in non-treated animals. These results suggest that the spontaneous glomerular lesion of APA hamsters is modified qualitatively and quantitatively by SZ-induced diabetes.     

An evaluation of lectin-mediated magnetic bead cell sorting for the targeted separation of enteric bacteria

Lectin-labelled magnetic beads were assessed and compared with antisera as an alternative approach for the targeted separation and isolation of enteric bacteria. Of the 16 lectins tested against a range of bacterial species, concanavalin A (conA) showed the greatest potential. Agglutination of bacterial cells in suspension using conA and methods for effective labelling of the magnetic beads with the lectin were optimized. ConA-labelled magnetic beads were compared with antibody-labelled beads for recovery of bacterial cells from pure or mixed laboratory cultures and from natural populations in river water. Recovered cell populations were free from environmental impurities and a high percentage of the culturable cells was extracted. Specific cell recovery was found to be variable, but the use of lectins offers some promise as an alternative cell discriminator.