Putting 'X' into context: the diversity of 'Candidatus Phytoplasma pruni' strains associated with the induction of X-disease

Recurrent epiphytotics of X-disease, caused by 'Candidatus Phytoplasma pruni', have inflicted significant losses on commercial cherry and peach production across North America in the last century. During this period, there have been multiple studies reporting different disease phenotypes, and more recently, identifying different strains through sequencing core genes, but the symptoms have not, to date, been linked with genotype. Therefore, in this study we collected and assessed differing disease phenotypes from multiple U.S. states and conducted multi-locus sequence analysis on these strains. We identified a total of five lineages associated with the induction of X-disease on commercial Prunus species and two lineages that were associated with wild P. virginiana. Despite a century of interstate plant movement, there were regional trends in terms of lineages present, and lineage-specific symptoms were observed on P. avium, P. cerasus, and P. virginiana, but not on P. persica. Cumulatively, these data have allowed us to define 'true' X-disease-inducing strains of concern to the stone fruit industry across North America, as well as potential sources of infection that exist in the extra-orchard environment.

Detection and differentiation of herbicide stresses in roses by Raman spectroscopy

Herbicide application is a critical component of modern horticulture. Misuse of herbicides can result in damage to economically important plants. Currently, such damage can be detected only at symptomatic stages by subjective visual inspection of plants, which requires substantial biological expertise. In this study, we investigated the potential of Raman spectroscopy (RS), a modern analytical technique that allows sensing of plant health, for pre-symptomatic diagnostics of herbicide stresses. Using roses as a model plant system, we investigated the extent to which stresses caused by Roundup (Glyphosate) and Weed-B-Gon (2, 4-D, Dicamba and Mecoprop-p (WBG), two of the most commonly used herbicides world-wide, can be diagnosed at pre- and symptomatic stages. We found that spectroscopic analysis of rose leaves enables ~90% accurate detection of Roundup- and WBG-induced stresses one day after application of these herbicides on plants. Our results also show that the accuracy of diagnostics of both herbicides at seven days reaches 100%. Furthermore, we show that RS enables highly accurate differentiation between the stresses induced by Roundup- and WBG. We infer that this sensitivity and specificity arises from the differences in biochemical changes in plants that are induced by both herbicides. These findings suggest that RS can be used for a non-destructive surveillance of plant health to detect and identify herbicide-induced stresses in plants.

First Report of Tar Spot on Corn Caused by Phyllachora maydis in the Great Plains

Tar spot caused by the fungus Phyllachora maydis Maubl. is a significant foliar disease of corn (Zea mays L.). Threatening corn production across the Americas, this disease can reduce the quality of silage and grain yield (Rocco da Silva et al. 2021; Valle-Torres et al. 2020). Lesions caused by P. maydis are usually black, glossy, and raised stromata on the leaf surface and occasionally on the husk. (Liu 1973; Rocco da Silva et al. 2021). Samples consistent with tar spot of corn were collected between September and October of 2022 from 6 fields in Kansas, 23 in Nebraska, and 6 in South Dakota. One sample was selected from each of the three states for further microscopic evaluation and molecular analysis. Signs of the fungus were visually and microscopically confirmed in eight Nebraska counties in October 2021; however, in the 2021, season tar spot sings were not found in Kansas and South Dakota. In the 2022 season disease severity varied by location; some fields in Kansas had <1% incidence, whereas in South Dakota disease incidence approached 1-2%, and in Nebraska between <1-5%. Stromata were present on both green and senescing tissues. Morphological characteristics of the pathogen were similar and consistent with the description of P. maydis (Parbery 1967) from all examined leaves across all locations. Asexual spores (conidia) were produced in pycnidial fruiting bodies ranging in size 1.29 to 2.82 x 8.84 to 16.95 µm (n = 40, average 1.98 × 13.30 μm). The pycnidial fruiting bodies were often found adjacent to perithecia within the stromata. For molecular confirmation, stromata were aseptically removed from leaves collected at each location and DNA extracted using a phenol chloroform method. The internal transcribed spacer (ITS) regions of the ribosomal RNA gene were sequenced using ITS1/ITS4 universal primers (Larena et al. 1999). Amplicons were Sanger sequenced (Genewiz, Inc., South Plainfield, NJ), and a consensus sequence for each sample was deposited in GenBank: Kansas (OQ200487), Nebraska (OQ200488), and South Dakota (OQ200489). Using the BLASTn, sequences from Kansas, Nebraska and South Dakota showed 100% homology with 100% query cover to other P. maydis GenBank accessions (MG881848.1; OL342916.1; OL342915.1). Koch's postulates were not performed given the obligate nature of the pathogen (Muller and Samuels 1984). This report documents the first confirmation of tar spot on corn in Kansas, Nebraska, and South Dakota (Great Plains).

Titer and Distribution of 'Candidatus Phytoplasma pruni' in Prunus avium

'Candidatus Phytoplasma pruni' infection in cherries causes small, misshapen fruit with poor color and taste, rendering the fruit unmarketable. However, this is a disease with a long development cycle and a scattered, nonuniform symptom distribution in the early stages. To better understand the biology as well as the relationship between pathogen titer and disease expression, we carried out seasonal, spatial, and temporal examinations of 'Ca. P. pruni' titer and distribution in infected orchard-grown trees. Sequential sampling of heavily infected trees revealed marked seasonal patterns, with differential accumulation in woody stem and leaf tissues and, most notably, within fruit in the early stages of development from bloom to pit hardening. Furthermore, mapping phytoplasma distribution and titer in trees at different stages of infection indicated that infection proceeds through a series of stages. Initially, infection spreads basipetally and accumulates in the roots before populating aerial parts of the trees from the trunk upward, with infection of specific tissues and limbs followed by an increasing phytoplasma titer. Finally, we observed a correlation between phytoplasma titer and symptom severity, with severe symptom onset associated with three to four orders of magnitude more phytoplasma than mild symptoms. Cumulatively, these data aid in accurate sampling and management decision-making and furthers our understanding of disease development.

Dynamics of picosecond laser ablation for surgical treatment of colorectal cancer

Endoluminal surgery for the treatment of colorectal neoplasia is typically carried out using electrocautery tools which imply limited precision and the risk of harm through collateral thermal damage to the adjacent healthy tissue. As a potential alternative, we present the successful colonic epithelial laser ablation by means of picosecond laser pulses. Laser ablation studies performed in ex-vivo colon tissue result in cavities with comparable thickness to early stage colorectal cancers. The corresponding histology sections exhibit only minimal collateral damage to the surrounding tissue and the depth of the ablation can be controlled precisely by means of the pulse energy. High-speed imaging has been used for the first time to visualize picosecond laser ablation of cancerous tissue in a clinically relevant model. This information was correlated with histopathology and optical surface profilometry revealing the dynamic nature of the laser tissue interaction and the need for temporal or spatial separation of pulses for optimum efficacy with regards to tissue removal. Overall, the application of picosecond laser pulses to ablate endoluminal bowel lesions demonstrates significantly improved precision and reduced thermal damage to the adjacent tissue in comparison to conventional procedures and hence will enable more precise surgical treatment of cancers.

Raman spectroscopy as an early detection tool for rose rosette infection

Hand-held Raman spectroscopy is a potential tool for a confirmatory, non-invasive, and non-destructive detection and identification of rose rosette disease. Using this spectroscopic approach, structural changes in roses that are associated with this viral infection can be revealed. The commercial rose shrub industry in the United States is one of the largest of its kind. All commercial rose varieties are susceptible to rose rosette disease (RRD), a deadly viral disease vectored by eriophyid mites. This disease is typically diagnosed visually and/or by PCR-based detection assays. The present work demonstrates that Raman spectroscopy can detect RRD in intact leaf tissue. It is shown that chemometric analysis can distinguish between spectra collected from symptomatic and asymptomatic tissue, as well as between healthy and asymptomatic tissue. This method will be useful as an initial screen for RRD prior to PCR analysis to help conserve reagents and save time.

Challenges of Breeding Rose Rosette–resistant Roses

Rose rosette disease (RRD) whose causal agent, the Emaravirus Rose rosette virus (RRV), was only recently identified has caused widespread death of roses in the midwestern and eastern sections of the United States. A national research team is working on the detection and best management practices for this highly damaging disease. Unfortunately, little is known about the host plant resistance to either the causal viral agent or its vector, the eriophyid mite Phyllocoptes fructiphilus. Thus far, the only confirmed resistance is among Rosa species. Of the over 600 rose cultivars observed, only 7% have not exhibited symptoms of RRD. Replicated trials are in progress to confirm resistance and/or susceptibility of ≈300 rose accessions in Tennessee and Delaware. Rose is a multispecies cultivated complex that consists of diploid, triploid, and tetraploid cultivars. The basic breeding cycle is 4 years with a 3-year commercial trial coupled with mass propagation before release. Thus, if only one breeding cycle is needed, a new cultivar could be produced in 7 years. Unfortunately, for the introgression of a new trait such as disease resistance from a related species into the commercial rose germplasm, multiple generations are required which can easily take two decades from the first cross to cultivar release. Research is ongoing to develop a rapid selection procedure for resistance to RRD with the aid of molecular markers associated with the resistance. Such an approach has the potential of reducing the breeding cycle time by 50% and increasing the efficiency of seedling and parental selection manifold, leading to commercially acceptable rose cultivars with high RRD resistance in less time and with less expense.

PLGA microspheres encapsulating siRNA anti-TNFalpha: efficient RNAi-mediated treatment of arthritic joints

The aim of this study was to investigate potentialities of poly(dl-lactide-co-glycolide) (PLGA) microspheres for the delivery of small interfering RNAs (siRNAs) against tumor necrosis factor α (TNF-α) to achieve prolonged and efficient inhibition of TNF-α for the treatment of rheumatoid arthritis (RA). PLGA microspheres were prepared by a modified multiple emulsion-solvent evaporation method. The formulations were characterized in terms of morphology, mean diameter and siRNAs distribution, encapsulation efficiency, and in vitro release kinetics. The efficiency of this system was then evaluated both in vitro and in vivo using the murine monocytic cell line J774 and a pre-clinical model of RA, respectively. siRNA-encapsulating PLGA microspheres were characterized by a high encapsulation efficiency and a slow and prolonged anti-TNF-α siRNAs. Our results provide evidence that, upon intra-articular administration, PLGA microspheres slowly releasing siRNAs effectively inhibited the expression of TNF-α in arthritic joints. Our system might represent an alternative strategy for the design of novel anti-rheumatic therapies based on the use of RNA interference in RA.

Both isoforms of ketohexokinase are dispensable for normal growth and development

Dietary fructose intake has dramatically increased over recent decades and is implicated in the high rates of obesity, hypertension, and type 2 diabetes (metabolic syndrome) in Western societies. The molecular determinants of this epidemiologic correlation are incompletely defined, but high-flux fructose catabolism initiated by ketohexokinase (Khk, fructokinase) is believed to be important. The Khk gene encodes two enzyme isoforms with distinctive substrate preferences, the independent physiological roles of which are unclear. To investigate this question, and for testing the importance of Khk in metabolic syndrome, isoform-selective genetic lesions would be valuable. Two deficiency alleles of the mouse Khk gene were designed. The first, Khk3a, uses targeted “knock-in” of a premature termination codon to induce a selective deficiency of the minor Khk-A isoform, preserving the major Khk-C isoform. The second, the KhkΔ allele, ablates both isoforms. Mice carrying each of these Khk-deficiency alleles were generated and validated at the DNA, RNA, and protein levels. Comparison between normal and knockout animals confirmed the specificity of the genetic lesions and allowed accurate analysis of the cellular distribution of Khk within tissues such as gut and liver. Both Khk3a/3a and KhkΔ/Δ homozygous mice were healthy and fertile and displayed minimal biochemical abnormalities under basal dietary conditions. These studies are the first demonstration that neither Khk isoform is required for normal growth and development. The new mouse models will allow direct testing of various hypotheses concerning the role of this enzyme in metabolic syndrome in humans and the value of Khk as a pharmacological target.

Influence on energy kinetics and histology of different preservation solutions seen during cold ischemia in the liver

BACKGROUND AND PURPOSE

Cold flush preservation prolongs tissue viability during ischemia. However, there is little understanding of the effects of various preservation fluids on events during this period. A study of cold ischemia in rat livers was undertaken to compare biochemical and histological changes over time, using three preservation solutions: University of Wisconsin (UW), histidine-tryptophan-ketoglutarate (HTK), and Leeds solution (LS) under development at our institution. Leeds solution is a phosphate-based sucrose solution that like UW contains the impermeant lactobionate and the metabolite allopurinol (1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one) which acts as a competitive inhibitor of xanthine oxidase, stopping the breakdown of hypoxanthine to xanthine by oxidizing it to alloxanthine, inhibiting both the conversion of hypoxanthine to xanthine and the conversion of xanthine to uric acid.

MATERIALS AND METHODS

At various time points, samples were analyzed for adenosine triphospate (ATP) and metabolites by high-performance liquid chromatography as well as for histological changes.

RESULTS

In all livers, ATP, ADP, and AMP degraded over 4 hours. In UW and LS groups, degradation beyond hypoxanthine was halted, and it continued in the HTK group. This blockade led to a significant reduction in the accumulation of xanthine and uric acid. Histological analysis showed protected architecture and maintenance of reticulin scaffolds in the UW and LS groups, whereas tissue breakdown was seen from earlier time points in the HTK group. Additionally, throughout ischemia, signs of pathological injury were more pronounced with UW- than with LS-preserved tissue.

CONCLUSIONS

These results implied that cold ischemia in the liver is characterized by dynamic biochemical changes coincident with pathological injury which are initiated from the time of organ perfusion and influenced by the choice of the perfusion fluid. Allopurinol in UW and LS appears to be critical. We hypothesized that it may also affect the degree of subsequent reperfusion injury. The data supported the assertion that LS offerred improved preservation over UW, adding to the impetus to shorten ischemic times in clinical transplantation.

The bradykinin response and early hypotension at the introduction of continuous renal replacement therapy in the intensive care unit

We assessed the relationship of certain clinical variables (including bradykinin [BK] release and dialysis membrane) to initial mean arterial pressure (MAP) reduction in 47 patients requiring continuous renal replacement therapy (CRRT) in an intensive care unit. The pretreatment MAP was 84 +/- 14 mm Hg for the group as a whole. The initial MAP reduction was 11.5 (7-20) mm Hg, occurring 4 to 8 min after connection. MAP reduction was 9 (6-15) mm Hg with polyacryonitrile (PAN) membranes versus 14 (5-19) mm Hg with polysulfone (PS) (not significant). There were positive correlations between MAP reduction and BK concentration at 3 (BK3; r = 0.58, p < 0.01) and 6 (BK6; r = 0.67, p < 0.001) min with PAN but not with PS. A greater reduction in MAP was seen in patients who were not receiving inotropic support (Mann-Whitney test, p < 0.01). BK3 and BK6 values for the PAN and PS groups were not significantly different. However, BK concentrations greater than 1,000 pg/ml were only seen with PAN (6 patients, MAP reduction 27 [17-31] mm Hg). There were positive (albumin) and negative (age; acute physiology, age, and chronic health evaluation score; C-reactive protein [CRP]; calcium) correlations with BK3/BK6 in the PAN and PS groups, some of which (albumin, CRP) reached statistical significance. In summary, MAP reduction at the start of CRRT correlates with BK concentration. The similarity of response with PAN and PS suggests an importance for other clinical factors. In this study, hemodynamic instability was more likely in patients with evidence of a less severe inflammatory or septic illness.

Renal diagnosis without renal biopsy. Nephritis and sensorineural deafness

Two examples of hereditary nephropathy within the context of clinical syndromes are described. Emphasis is put on the ability to make a renal diagnosis without renal biopsy and the benefits of screening relatives once a diagnosis is achieved. A variant of Alport's syndrome with associated macrothrombocytic thrombocytopenia, known as Epstein's syndrome, is reported. In addition siblings with Alström's syndrome characterized by pigmentary retinal degeneration (causing blindness in early childhood), progressive sensorineural hearing loss, and progressive renal failure are reported. Both cases had previously presented for non-renal pathology in advance of the onset of symptomatic renal failure and may have benefited from appropriate screening.

Expression of an antigen associated with basal bodies of human ciliated epithelial cells

The process and regulation of ciliogenesis in human epithelia is little understood and many components of the cilium and associated structures have not been characterised. We have identified a monoclonal antibody, LhS28, which recognises a 44,000-45,000 M(r) protein specifically associated with human ciliated epithelial cells. Immunoperoxidase labelling of formalin-fixed paraffin wax-embedded human tissues showed that LhS28 was expressed in the sub-apical zone of ciliated epithelial cells of the Fallopian tube and upper respiratory tract, but not ciliated ependyma, non-ciliated epithelia or testis containing developing spermatozoa. Immunoelectron microscopy demonstrated that the antigen recognised by LhS28 was associated with the basal body structure of the cilium and specifically with the 9 + 0 microtubule arrays. LhS28 should be a useful tool in the identification of ciliated cells in pathological specimens and for investigating mechanisms of ciliogenesis.

High risk of lymphomas in children of Asian origin: ethnicity or confounding by socioeconomic status?

To examine the role of ethnic origin as a risk factor for paediatric lymphoma, a cancer registry-based analysis was undertaken in Yorkshire, UK. Children of Asian ethnic origin were found to have an odds ratio for lymphomas of 1.60 (CI 0.98-2.62), after adjusting for age and sex. After adjusting also for 'super profile group' as an indicator of socioeconomic status, the estimate became 1.99 (CI 1.08-3.68). Hodgkin's disease and non-Hodgkin's lymphomas were analysed separately with similar results. Super profile group is an area-based measure and may not reflect the individual variation in living standards, especially among the Asian immigrants. Our results indicate that socioeconomic status does not confound the relationship between lymphomas and ethnic origin. However, there is a need for studies of ethnicity that include indicators of individual living standards or socioeconomic status.

Alterations of glomerular basement membrane charge and structure in diabetic nephropathy

We examined glomerular basement membrane anionic site distribution identified by cationic gold in seven patients with insulin-dependent and four patients with non-insulin-dependent diabetes mellitus, presenting a spectrum of clinical and glomerular changes. Anionic sites were investigated by pretreatment of tissue with glycosaminoglycan-degrading enzymes prior to cationic gold staining. The distribution of chondroitin sulphate proteoglycans--a previously unrecognized glomerular basement membrane component--and type IV collagen was examined by immunoelectron microscopy to identify structural changes in the basement membrane. Findings were compared with those of non-diabetic patients showing minor proteinuria and morphologically normal glomerular basement membranes. Two patients, originally diagnosed as having diabetic nephropathy were also examined at 19 weeks and 5 years after renal transplantation. Characteristic redistribution of type IV collagen and chondroitin sulphate proteoglycans was noted in thickened glomerular basement membrane segments (> 400 nm) of diabetic patients and those with renal transplants. Extension of anionic sites deep into the glomerular basement membrane at pH 2.5, together with loss of interna sites at pH 5.8 is unique to diabetic nephropathy. Reduced charge density was apparent in some patients due to thickening of the glomerular basement membrane, although the number of anionic sites per unit length of membrane was actually increased. Thus, charge aberration in diabetic nephropathy is due to displacement rather than loss of anionic sites. Removal of more than 90% of these sites by heparitinase, confirms their association with heparan sulphate proteoglycans. Similar derangement of anionic sites in all patients with diabetic nephropathy irrespective of the degree of proteinuria, suggests that a heparan sulphate proteoglycan-related charge barrier plays a minor role in controlling permeability of the diabetic glomerular basement membrane.

Clinical features and outcome of patients with thin and ultrathin glomerular membranes

There is considerable disagreement regarding the natural history of renal disease associated with thin glomerular basement membranes (TGBM). We followed 43 patients (19 male), mean age 41.6 years (range 19-73) for a mean of 88 months (48-140). TGBM was recognized in adults when glomerular basement membrane thickness, measured from multiple sites in electronmicrographs of renal biopsy tissue as the harmonic mean, was < 320 nm. At presentation, 95% had microscopic haematuria, 12% macroscopic haematuria, 14% loin pain, 28% proteinuria, and 14% hypertension. There was no difference in GBM width between the sexes (male 258 nm vs. female 251 nm) but there was a significant negative correlation between age and GBM width (r = -0.53, p < 0.001), with older patients having the thinnest membranes. Twenty six patients had ultrathin GBM (< 270 nm), of whom 54% had 3+ haematuria vs. 12% of the group with BM > 270 nm (p < 0.01). In the ultrathin group, 71% had loss of anionic charge from the GBM, vs. 17% in those with membranes which were thin but > 270 nm (p < 0.05). Proteinuria occurred more frequently in those with GBM > 270 nm, 65% vs. 8% in the ultrathin group (p < 0.01). Thin GBM were associated with a benign prognosis, as after a mean follow-up of 85 months (48-140), there was no significant change in either serum creatinine or mean arterial blood pressure. Patients with ultrathin GBM had greater loss of GBM anionic charge, which might result in both an alteration of flow characteristics within the glomerular capillaries and also increased fragility of the glomerular basement membrane with likelihood of rupture and resultant macroscopic haematuria.

Cationic gold staining of glomerular anionic sites in archived tissue, reprocessed from paraffin wax into LR gold resin

Glomerular capillary wall anionic sites have been demonstrated by cationic gold staining of archived renal biopsy tissue (up to 10 years old), obtained from six patients, originally embedded in paraffin wax, and subsequently reprocessed into LR gold resin. The staining patterns at pH 2.5 and pH 7.0, demonstrating different glomerular basement membrane (GBM) anionic constituents, were compared in three patients from whom tissue directly processed into LR gold and reprocessed tissue was available. Ultrastructural preservation was poorer and shrinkage artefact greater in paraformaldehyde-lysine periodate (PLP) as opposed to formol saline-fixed reprocessed tissue. However, GBM anionic site expression was well preserved, or even enhanced (lamina rara externa, pH 7.0) in reprocessed tissue, using either fixative. Although it may not be possible to compare subtle changes in anionic site distribution in variously fixed and processed tissues, due to these artefacts, the technique enables retrospective study of charge status in archived material from disease groups in which there are distinct anionic site aberrations.

Preparation and use of the poly-L-lysine-gold probe: a differential marker of glomerular anionic sites

The conditions required for the production of a polylysine-coated gold (PL-G) complex, which shows optimal sensitivity for the demonstration of tissue anionic sites, expressed under different conditions of pH have been investigated. Problems encountered with this complex have been compared with those found with other methods of conjugation of polylysine to colloidal gold. The performance of a bovine serum albumin (BSA)-stabilized PL-G complex was examined against other PL-G conjugates, including complexes that are commercially available, for the detection of heterogeneous glomerular anionic site populations, expressed at pH 2.5 and pH 7.0.

Detection of glomerular anionic sites in post-embedded ultra-thin sections using cationic colloidal gold

We detected glomerular anionic sites in fixed, LR Gold-embedded ultra-thin tissue sections using cationic colloidal gold. Manual and computer-assisted quantitation were compared, and the influence of pH and glycosaminoglycan-degrading enzymes on site expression was examined. Both quantitation methods produced similar results. Alteration of pH within a narrow range (pH 2.5-3.0) markedly affected the staining pattern. At pH 2.5, epithelial and endothelial glycocalyx and regular sites restricted to the lamina rara externa were stained. At pH 3.0 and above, glycocalyx was unstained but intracellular and nuclear staining was present; glomerular basement membrane (GBM) and mesangial matrix sites were abundant. After chondroitinase ABC or hyaluronidase digestion, GBM staining was eliminated at pH 2.0 and reduced at pH 7.0 (p less than 0.001), suggesting that degraded sites are associated with chondroitin sulfate or hyaluronic acid. By contrast, prolonged heparitinase I digestion was ineffective at either pH. Digestion of purified substrates revealed crossreactivity of heparitinase towards chondroitin sulfate and of chondroitinase towards hyaluronic acid. Since tissue sites were reduced by chondroitinase but not heparitinase, we suggest that degradation is due to hyaluronidase activity of chondroitinase and the anionic sites are associated with hyaluronic acid. However, the influence of pH indicates that lamina rara externa sites are structurally distinct from other GBM anionic sites.

Cationic colloidal gold--a novel marker for the demonstration of glomerular polyanion status in routine renal biopsies

Investigations of glomerular anionic charge status in human renal biopsies have previously been restricted, by the techniques and markers used, to staining of sites in pre-embedded tissue. The introduction of a novel marker, cationic colloidal gold, which demonstrates fixed anionic sites in hydrophilic resin (LR Gold)-embedded, ultrathin tissue sections, has now enabled glomerular charge to be evaluated in routine biopsy material. The cationic gold marker detects components which express anionic charge under different pH conditions. The patterns of staining in tissue showing minor glomerular pathology and low proteinuria, together with enzyme-digestion studies indicate that anionic sites are normally associated with heparan sulphate proteoglycans, glycocalyx sialoproteins, hyaluronic acid, and other GBM components which have not yet been characterised. Several charge aberrations involving different pathological mechanisms have been identified using cationic gold. These aberrations may be categorised according to the pathological basis of the charge pattern defect, rather than glomerular disease classification, as a prelude to the precise identification of the anionic sites and their functional importance in relation to the glomerular charge selectivity barrier. The categories which have been defined are: (1) 'Normal', (2) interrupted, (3) neutralised, (4) structurally disorganised, and (5) depleted. As sites are further characterised sub-categorisation is likely. We anticipate that this approach will help to elucidate both the participation of charged components in disease pathogenesis and their role in relation to glomerular proteinuria.

Immunogold-silver staining of mesangial antigen in lowicryl K4M- and LR gold-embedded renal tissue using epipolarization microscopy

We examined the localization of a glomerular mesangial antigen with a Thy-1.1 monoclonal antibody by epipolarization microscopy (EPI) of silver-enhanced, immunogold-stained renal tissue embedded in LR Gold and Lowicryl K4M, and compared the attributes of these hydrophilic resins. Antigen was well preserved in tissue embedded in both resins. LR Gold-embedded tissue demonstrated excellent immunostaining properties, sectioned more easily, and showed better durability during staining than K4M. Lowicryl K4M-embedded tissue, however, displayed a phenomenon of self-illumination when counterstained with eosin which was not seen with LR Gold. This enabled immunostaining to be precisely related to tissue morphology without the necessity of simultaneous transillumination, which can be problematic when used in combination with EPI because of reflection of incident illumination from sub-stage optical surfaces.

Spontaneous glomerular immunoglobulin deposition in young Sprague-Dawley rats

The frequency, age-onset and distribution of spontaneously deposited immunoglobulins (Igs) in glomeruli of Sprague-Dawley rats has been investigated. Groups of rats (n = 10) were examined at 4-7 day intervals from birth (presuckling) until 30 days of age. Findings were compared with circulating immunoglobulin concentrations in each age group. Immunoglobulins were undetectable in immature kidneys of newborn rats. However, as early as 5 days, scanty IgA and IgM deposits were observed predominantly in mesangial areas of mature glomeruli, corresponding to low circulating concentrations of these immunoglobulins. By contrast, glomerular IgG deposits were not observed until 21 days, despite relatively high concentrations of circulating maternal IgG from birth. Mesangial deposition of immunoglobulins increased with age. Absence of complement C3c or electron dense deposits associated with this mesangial localization suggests that immunoglobulins were not deposited as immune complexes. Accumulation of non-phlogogenic immunoglobulins in the mesangium of normal rats supports the concept that the mesangium is constantly perfused by circulating macromolecules and filtration residues. The results indicate problems of interpretation of the significance of endogenous immunoglobulin deposition in models of experimental glomerulonephritis, even in studies involving weanling rats.

Solitary osteochondroma of the radius in three horses

Osteochondroma of the distal portion of the radius was diagnosed in 3 horses with a history of lameness and distention of the common tendon sheath of the superficial and deep digital flexor tendons at the level of the carpal canal. In 2 horses, the exostosis was removed through an incision at the caudal border of the lateral digital extensor muscle above the carpal ligament.

Preparation, purification and analysis of BSA-coated latex particles for in vivo studies. Non-ionic adsorbance of unbound protein ligand

A procedure for the preparation, purification and analysis of small, BSA-coated carboxylate-modified latex (CML) particles, suitable for use in in vivo studies has been developed. Following conjugation, uptake of unbound BSA by Amberlite XAD-8 non-ionic adsorbent beads has been shown to be an effective method by which unbound protein ligands may be removed from coated latex preparations.

Uptake and disposal of BSA-coated latex particles by the rat mesangium: reaction with subsequently administered heterologous antiserum

Mesangial uptake and disposal of antigen-coated latex particles and the ability of subsequently injected antibody to maintain complexed antigen in the rat mesangium has been investigated. Carboxylate-modified latex particles, coated with bovine albumin (BSA) were injected i.v. to 36 Wistar rats. Twenty-two rats (group 1) were not treated further. Fourteen rats (group 2) received rabbit anti-BSA antiserum i.v. and i.p. 24 h later. Control groups were injected with uncoated, unmodified latex particles or soluble BSA with and without subsequent antibody administration. Latex was present in the mesangial matrix of rats in group 1 at 1 h in association with a diffuse mesangial distribution of BSA. At 24 h, BSA staining was markedly reduced and extracellular latex was no longer observed. Intracellular latex aggregates were present in experimental and control groups at 24 h-14 days in cytoplasmic vacuoles of hypertrophic mesangium which showed minor infiltration by macrophage-like cells. Progressive removal of latex aggregates coincided with declining mesangial reactivity. Rapid disappearance of antigen apparently results from local degradation of tracer in the mesangium. Antibody administration preserves BSA in the mesangium due to immune complex formation and is associated with retention of ingested latex by mesangial cells. However, efficient disposal of glomerular immune deposits by the mesangium appears to minimize infiltration by monocytes and prevents aggravation of glomerular inflammation.

Persistence of inert macromolecules (Imposil) in the rat mesangium and glomerular functional disturbance

Imposil iron-dextran is an inert tracer that has been used to study mesangial uptake and clearance of macromolecular material from the glomerular circulation. Such a tracer may be a useful marker of altered mesangial function in animals with some forms of glomerulonephritis. We have studied mesangial handling of intravenously injected Imposil (50 mg/100 g body weight) in normal rats by light, immunofluorescence and electron microscopy for up to 3 months. Mesangial cell uptake was maximal at 48-54 h. Extrusion and drainage of tracer to the vascular pole and distal tubule was evident at 3 days but iron was still present in mesangial cells at 3 months. Possible functional renal impairment resulting from persistent mesangially sequestered tracer was examined by measuring daily urine protein and iron excretion. A possible relationship between failure of mesangial cells to eliminate inert tracer and increasing glomerular permeability is demonstrated, suggesting that Imposil and similar inert macromolecules cannot be used for long-term studies of mesangial function.