The Role of the NLRP3 Inflammasome in Mediating Glomerular and Tubular Injury in Diabetic Nephropathy.

The NOD-like receptor protein 3 (NLRP3) inflammasome is a multi-protein signalling complex integral to the chronic inflammatory response, activated in response to sterile and non-sterile cellular damage. The assembly and activation of the NLRP3 inflammasome comprise a two-step process involving nuclear factor kappa B (NFkB)-mediated priming, followed by canonical, non-canonical or alternative signalling pathways. These result in the maturation and release of inflammatory cytokines interleukin 1 beta (IL1ß) and interleukin-18 (IL18), which are associated with chronic inflammatory conditions including diabetic kidney disease. Diabetic nephropathy is a condition affecting ∼40% of people with diabetes, the key underlying pathology of which is tubulointerstitial inflammation and fibrosis. There is growing evidence to suggest the involvement of the NLRP3 inflammasome in this chronic inflammation. Early deterioration of kidney function begins in the glomerulus, with tubular inflammation dictating the progression of late-stage disease. Priming and activation of the NLRP3 inflammasome have been linked to several clinical markers of nephropathy including proteinuria and albuminuria, in addition to morphological changes including mesangial expansion. Treatment options for diabetic nephropathy are limited, and research that examines the impact of directly targeting the NLRP3 inflammasome, or associated downstream components are beginning to gain favour, with several agents currently in clinical trials. This review will explore a role for NLRP3 inflammasome activation and signalling in mediating inflammation in diabetic nephropathy, specifically in the glomerulus and proximal tubule, before briefly describing the current position of therapeutic research in this field.

Markers of cell division cycle in glioblastoma: significance in prediction of treatment response and patient prognosis.

OBJECTIVE: To investigate whether expression of regulatory components of the cell division cycle can be used independently to predict survival and response to adjuvant therapy in glioblastomas. METHOD: A tissue micro-array, constructed using glioblastomas (n = 66), was stained using antibodies against minichromosome maintenance protein-2 (Mcm-2), expressed throughout the cell-division cycle; geminin, a protein that prevents re-initiation of DNA replication; and cyclin A, an S-phase cyclin. A semi-quantitative labelling index (LI) was calculated using an average of 18 high-power fields (hpf) in three replicate cores. The patients were divided into two groups: Group 1 (n = 50) underwent surgery and radiotherapy with 24 patients receiving temozolomide, and Group 2 (n = 16) received surgical treatment only. RESULTS: The LIs (median +/- IQR) for Group 1 were as follows: Mcm-2, 36.7% (22.9%-51.8%); geminin, 7.8% (5.8%-10.5%); and cyclin A, 4.2% (2.4%-6.9%). Elevated LIs, higher than the median, for geminin and cyclin A correlated with prolonged survival when the tumours received adjuvant therapy (Kaplan-Meier curves, p = 0.0046 and p = 0.0063 for geminin and cyclin A, respectively). Linear regression analysis revealed positive correlations with survival for Mcm-2 (p = 0.0376), geminin (p = 0.0006) and cyclin A (p = 0.004). In Group 2, there was no relationship between the patient survival and the LI for any marker. CONCLUSIONS: Geminin and cyclin A, each show potential as independent prognostic markers in glioblastomas receiving adjuvant therapy. This may reflect the fact that both geminin and cyclin A estimate proliferating tumour cell subpopulations sensitive to radio/chemotherapy. These markers could provide valuable prognostic information, even in small biopsies, especially if combined with O(6)MGMT expression and 1p;19q deletion status.

TGFß modulates cell-to-cell communication in early epithelial-to-mesenchymal transition.

AIMS/HYPOTHESIS: A key pathology in diabetic nephropathy is tubulointerstitial fibrosis. The condition is characterised by increased deposition of the extracellular matrix, fibrotic scar formation and declining renal function, with the prosclerotic cytokine TGF-ß1 mediating many of these catastrophic changes. Here we investigated whether TGF-ß1-induced epithelial-to-mesenchymal transition (EMT) plays a role in alterations in cell adhesion, cell coupling and cell communication in the human renal proximal tubule. METHODS: Whole-cell and cell compartment abundance of E-cadherin, N-cadherin, snail, vimentin, ß-catenin and connexin-43 was determined in human kidney cell line (HK)2 and human proximal tubule cells with or without TGF-ß1, using western blotting and immunocytochemistry, followed by quantification by densitometry. The contribution of connexin-43 in proximal tubule cell communication was quantified using small interfering RNA knockdown, while dye-transfer was used to assess gap junctional intercellular communication (GJIC). Functional tethering was assessed by single-cell force spectroscopy with or without TGF-ß1, or by immunoneutralisation of cadherin ligation. RESULTS: High glucose (25 mmol/l) increased the secretion of TGF-ß1 from HK2 cells. Analysis confirmed early TGF-ß1-induced morphological and phenotypical changes of EMT, with altered levels of adhesion and adherens junction proteins. These changes correlated with impaired cell adhesion and decreased tethering between coupled cells. Impaired E-cadherin-mediated adhesion reduced connexin-43 production and GJIC, these effects being mimicked by neutralisation of E-cadherin ligation. Upregulation of N-cadherin failed to restore adhesion or connexin-43-mediated GJIC. CONCLUSIONS/INTERPRETATION: We provide compelling evidence that TGF-ß1-induced EMT instigates a loss of E-cadherin, cell adhesion and ultimately of connexin-mediated cell communication in the proximal tubule under diabetic conditions; these changes occur ahead of overt signs of renal damage.

Investigation of 4-year-old stabilised/solidified and accelerated carbonated contaminated soil.

The investigation of the pilot-scale application of two different stabilisation/solidification (S/S) techniques was carried out at a former fireworks and low explosives manufacturing site in SE England. Cores and granular samples were recovered from uncovered accelerated carbonated (ACT) and cement-treated soils (S/S) after 4 years to evaluate field-performance with time. Samples were prepared for microstructural examination and leaching testing. The results indicated that the cement-treated soil was progressively carbonated over time, whereas the mineralogy of the carbonated soil remained essentially unchanged. Distinct microstructures were developed in the two soils. Although Pb, Zn and Cu leached less from the carbonated soil, these metals were adequately immobilised by both treatments. Geochemical modeling of pH-dependent leaching data suggested that the retention of trace metals resulted from different immobilisation mechanisms operating in the two soils examined.

Immobilisation of heavy metal in cement-based solidification/stabilisation: a review.

Heavy metal-bearing waste usually needs solidification/stabilization (s/s) prior to landfill to lower the leaching rate. Cement is the most adaptable binder currently available for the immobilisation of heavy metals. The selection of cements and operating parameters depends upon an understanding of chemistry of the system. This paper discusses interactions of heavy metals and cement phases in the solidification/stabilisation process. It provides a clarification of heavy metal effects on cement hydration. According to the decomposition rate of minerals, heavy metals accelerate the hydration of tricalcium silicate (C3S) and Portland cement, although they retard the precipitation of portlandite due to the reduction of pH resulted from hydrolyses of heavy metal ions. The chemical mechanism relevant to the accelerating effect of heavy metals is considered to be H+ attacks on cement phases and the precipitation of calcium heavy metal double hydroxides, which consumes calcium ions and then promotes the decomposition of C3S. In this work, molecular models of calcium silicate hydrate gel are presented based on the examination of 29Si solid-state magic angle spinning/nuclear magnetic resonance (MAS/NMR). This paper also reviews immobilisation mechanisms of heavy metals in hydrated cement matrices, focusing on the sorption, precipitation and chemical incorporation of cement hydration products. It is concluded that further research on the phase development during cement hydration in the presence of heavy metals and thermodynamic modelling is needed to improve effectiveness of cement-based s/s and extend this waste management technique.

The calcium-sensing receptor and insulin secretion: a role outside systemic control 15 years on.

In the 15 years since the identification and characterisation of the extracellular calcium-sensing receptor (CaR), it has become increasingly apparent that this cationic binding receptor is found in many tissues, not associated with the control of plasma calcium. One of these tissues is the pancreatic islet where insulin secretion provides the basis of energy regulation. It seems inherently unlikely that the islet responds to alterations in systemic calcium and a more plausible and intriguing possibility is that the CaR mediates cell-to-cell communication through local increases in the concentration of extracellular Ca(2+), co-released with insulin. This short article explores this possibility and suggests that this novel mechanism of cell communication, along with direct coupling via gap junctions and other local paracrine regulators helps explain why the glucose responsiveness of the intact islet is greater than the sum of the composite parts in isolation.

Characterisation of products of tricalcium silicate hydration in the presence of heavy metals.

The hydration of tricalcium silicate (C(3)S) in the presence of heavy metal is very important to cement-based solidification/stabilisation (s/s) of waste. In this work, tricalcium silicate pastes and aqueous suspensions doped with nitrate salts of Zn(2+), Pb(2+), Cu(2+) and Cr(3+) were examined at different ages by X-ray powder diffraction (XRD), thermal analysis (DTA/TG) and (29)Si solid-state magic angle spinning/nuclear magnetic resonance (MAS/NMR). It was found that heavy metal doping accelerated C(3)S hydration, even though Zn(2+) doping exhibited a severe retardation effect at an early period of time of C(3)S hydration. Heavy metals retarded the precipitation of portlandite due to the reduction of pH resulted from the hydrolysis of heavy metal ions during C(3)S hydration. The contents of portlandite in the control, Cr(3+)-doped, Cu(2+)-doped, Pb(2+)-doped and Zn(2+)-doped C(3)S pastes aged 28 days were 16.7, 5.5, 5.5, 5.5, and <0.7%, respectively. Heavy metals co-precipitated with calcium as double hydroxides such as (Ca(2)Cr(OH)(7).3H(2)O, Ca(2)(OH)(4)4Cu(OH)(2).2H(2)O and CaZn(2)(OH)(6).2H(2)O). These compounds were identified as crystalline phases in heavy metal doping C(3)S suspensions and amorphous phases in heavy metal doping C(3)S pastes. (29)Si NMR data confirmed that heavy metals promoted the polymerisation of C-S-H gel in 1-year-old of C(3)S pastes. The average numbers of Si in C-S-H gel for the Zn(2+)-doped, Cu(2+)-doped, Cr(3+)-doped, control, and Pb(2+)-doped C(3)S pastes were 5.86, 5.11, 3.66, 3.62, and 3.52. And the corresponding Ca/Si ratios were 1.36, 1.41, 1.56, 1.57 and 1.56, respectively. This study also revealed that the presence of heavy metal facilitated the formation of calcium carbonate during C(3)S hydration process in the presence of carbon dioxide.

Th1/Th2 cytokine imbalance in meningioma, anaplastic astrocytoma and glioblastoma multiforme patients.

The balance between Th1 and Th2 cytokines is thought to be an important factor in terms of tumour prognosis. Serum samples from 61 newly diagnosed patients with brain tumours and 50 age- and sex-matched non-tumour controls were analysed by ELISA for circulating levels of interleukin-12 (IL-12p70 and p40) and interleukin-10 (IL-10); pivotal Th1 and Th2 cytokines, respectively. Patients were divided into various groups depending on their histological diagnosis: meningioma (n=11), anaplastic astrocytoma (n=4) and glioblastoma multiforme (GBM; n=46). Significant reduction in serum IL-12 was seen in all groups as compared with the controls: meningioma, p=0.03; anaplastic astrocytoma, p<0.001; and GBM, p<0.001. Conversely, serum IL-10 was significantly increased in anaplastic astrocytoma, p=0.02, and GBM, p=0.03. The changes in the serum cytokines were not caused by the effects of steroids, as sequential analysis of patients pre- and post-steroid treatment commencement showed no difference. This study shows that patients with advanced primary intracranial malignancies have decreased circulating IL-12 and increased circulating IL-10, demonstrating that brain tumours have a major systemic effect on the immune system.

A review of accelerated carbonation technology in the treatment of cement-based materials and sequestration of CO2.

Moist calcium silicate minerals are known to readily react with carbon dioxide (CO2). The reaction products can cause rapid hardening and result in the production of monolithic materials. Today, accelerated carbonation is a developing technology, which may have potential for the treatment of wastes and contaminated soils and for the sequestration of CO2, an important greenhouse gas. This paper reviews recent developments in this emerging technology and provides information on the parameters that control the process. The effects of the accelerated carbonation reaction on the solid phase are discussed and future potential applications of this technology are also considered.

Solidification of stainless steel slag by accelerated carbonation.

On exposure to carbon dioxide (CO2) at a pressure of 3 bars, compacts formed from pressed ground slag, and 12.5 weight percent water, were found to react with approximately 18% of their own weight of CO2. The reaction product formed was calcium carbonate causing the slag to self-cement. Unconfined compressive strengths of 9MPa were recorded in carbonated compacts whereas strengths of < 1 MPa were recorded in non-carbonated slag compacts. As molten stainless steel slag containing dicalcium silicate (C2S) cools it can undergo several phase transitions. The final transformation from the beta-polymorph to gamma-C2S is accompanied by a volume change that causes the slag to self-pulverise or 'dust'. As a consequence of this the fine grained portion of the slag contains more of this phase whilst the coarser particles of the slag contain more of the calcium magnesium silicates that contribute the bulk of the waste. The fine fraction (< 125 microm) of the slag when ground is found to react to the same extent as the ground bulk slag and produces compacts with equivalent strength. A coarser fraction (4-8 mm) when ground to a similar grading does not react as extensively and produces a weaker product. Additions of ordinary Portland cement (OPC) at 5 and 10 percent by weight did not alter the degree of reaction during carbonation of the bulk slag or ground fine fraction, however the strength of the 4-8 mm fraction was increased by this change.

Acid neutralisation capacity of accelerated carbonated stainless steel slag.

The acid neutralisation capacity test is widely used to assess the long-term performance of waste materials prior to disposal. Samples of fixed mass are exposed to increasing additions of nitric add in sealed containers and the resultant pH is plotted as a titration curve. In this work, the add neutralisation capacity test was used in the assessment of an accelerated carbonated stainless steel slag. Difficulties arose in applying the test procedure to this material. This was largely because of the raised pressure from significant volumes of released carbon dioxide trapped in the sealed sample containers, causing an alteration to leachate pH values. Consequently, the add neutralisation capacity test was modified to enable testing of samples in equilibrium with the atmosphere. No adverse effects on the results from testing of a carbonate free material were recorded.

Microstructure of Portland cement pastes containing metal nitrate salts.

In recent years, Backscattered Scanning Electron microscopy techniques (BSE), coupled with an image analysis system have been recognised as a powerful tool for quantitative analysis. This paper investigates the effect of metal additions (Ba, Cu, Ni, Zn, Cr(III), Pb and Cd) to Portland cement to produce a solidified product which meets the durability criteria quantified by the ratio of hydrated products and porosity. In addition, other indicators of the progress of cement hydration such as the bulk density and evaporable water of the solidified products were also measured. Metal concentrations of 0.1 and 1% per weight of cement at a constant water/cement ratio of 0.4 were examined. The same measurements were conducted on control samples of different water/ cement ratio. The results have shown that the control samples at different W/C ratio showed consistent trend in residual cement porosity, density and evaporable water content. It also showed that low dosage of metal nitrate additions can reduce cement hydration by up to 50% and at the same time reduce the observable porosity. Overall, this work has shown that Scanning Electron Microscopy (SEM) and image analysis are powerful tools and could be used to quantify the observable porosity and cement hydration in solidified systems.

Long-term survival after mitral valve replacement in children aged <5 years: a multi-institutional study.

BACKGROUND: Short- and long-term outcomes after prosthetic mitral valve replacement (MVR) in children aged <5 years are ill-defined and generally perceived as poor. The experience of the Pediatric Cardiac Care Consortium (45 centers, 1982 to 1999) was reviewed. METHODS AND RESULTS: MVR was performed 176 times on 139 patients. Median follow-up was 6.2 years (range 0 to 20 years, 96% complete). Age at initial MVR was 1.9+/-1.4 years. Complications after initial MVR included heart block requiring pacemaker (16%), endocarditis (6%), thrombosis (3%), and stroke (2%). Patient survival was as follows: 1 year, 79%; 5 years, 75%; and 10 years, 74%. The majority of deaths occurred early after initial MVR, with little late attrition despite repeat MVR and chronic anticoagulation. Among survivors, the 5-year freedom from reoperation was 81%. Age-adjusted multivariable predictors of death include the presence of complete atrioventricular canal (hazard ratio 4.76, 95% CI 1.59 to 14.30), Shone's syndrome (hazard ratio 3.68, 95% CI 1.14 to 11.89), and increased ratio of prosthetic valve size to patient weight (relative risk 1.77 per mm/kg increment, 95% CI 1.06 to 2.97). Age- and diagnosis-adjusted prosthetic size/weight ratios predicted a 1-year survival of 91% for size/weight ratio 2, 79% for size/weight ratio 3, 61% for size/weight ratio 4, and 37% for size/weight ratio 5. CONCLUSIONS: Early mortality after MVR can be predicted on the basis of diagnosis and the size/weight ratio. Late mortality is low. These data can assist in choosing between MVR and alternative palliative strategies.

Correlation between increased colloid osmotic pressure and the resolution of refractory ascites after transjugular intrahepatic portosystemic shunt.

BACKGROUND: This study compared the changes in serum albumin, globulin, and colloid osmotic pressure (COP) before and after transjugular intrahepatic portosystemic shunt (TIPS) or large volume paracentesis (LVP) in patients with ascites. METHODS: Of 23 patients with refractory ascites, 17 had TIPS and 6 had LVP with infusion of albumin. Colloid osmotic pressure measurements were calculated, using the formula previously proposed by Hoefs: COP = A (1.058G + 0.163A + 3.11) where A = serum albumin and G = serum globulin. RESULTS: After 1 month, ascites resolved in 9 of the 17 patients who had TIPS and in none of the 6 who had LVP. Colloid osmotic pressure increased significantly in patients whose ascites resolved after TIPS. Colloid osmotic pressure did not change in the patients whose ascites did not resolve after TIPS, and COP decreased significantly in the LVP group. A statistically significant difference was found in the pre-TIPS COP measurements between those patients who had resolution of ascites and those who did not. A pre-TIPS COP of < or =20 mm Hg predicted resolution of ascites with an 88% sensitivity and a 78% specificity. CONCLUSIONS: Serum COP increased significantly in patients with resolution of ascites but remained unchanged in patients with persistent ascites after TIPS. Serum COP decreased after LVP. A statistically significant difference in the pre-TIPS COP was found between patients whose ascites resolved and patients having persistent ascites.

Zolmitriptan: a review of its use in migraine.

UNLABELLED: Zolmitriptan is a selective serotonin 5-HT1B/1D receptor agonist ('triptan'). Its efficacy and tolerability have been assessed in a number of randomised, placebo-controlled, double-blind trials in large numbers of adults with moderate to severe migraine attacks. Oral zolmitriptan 2.5 and 5mg has a rapid onset of action (significant headache relief is observed at 45 minutes) and efficacy is sustained in most patients who respond at 2 hours. The drug is significantly more effective than placebo as measured by a number of parameters including 2-hour headache response rates and pain-free response rates. Other symptoms of migraine, including nausea, photophobia and phonophobia are also alleviated with zolmitriptan. Zolmitriptan is effective in the treatment of migraine associated with menses and migraine with aura. There is some evidence to support the use of zolmitriptan in patients with migraine who have had a poor response to previous therapy. The efficacy of zolmitriptan appears to be maintained, with no tachyphylaxis, following repeated administration for multiple attacks of migraine over a prolonged period of time, with high headache response rates reported over all attacks. In comparison with placebo, the incidence of persistent migraine headache is reduced by zolmitriptan and recurrent migraine headache occurs less frequently with the active treatment. Zolmitriptan has also demonstrated efficacy in the treatment of persistent and/or recurrent migraine headache. For relief of migraine headache, zolmitriptan 5mg had similar efficacy to sumatriptan 100mg for a single attack, but generally was more effective than sumatriptan 25 and 50mg for multiple attacks, in single trials. The incidence of recurrent headache with zolmitriptan was similar to that with sumatriptan. Zolmitriptan is generally well tolerated with most adverse events being mild to moderate, transient and resolving without intervention or the need for treatment withdrawal. The most common adverse events with zolmitriptan therapy are asthenia, heaviness other than that of the chest or neck, dry mouth, nausea, dizziness, somnolence, paraesthesia, warm sensation, tightness, vasodilation and chest pain. CONCLUSION: Zolmitriptan is effective across a wide range of migraine subtypes, maintains efficacy when used in the long term and is generally well tolerated. Further clinical experience is necessary to define the position of zolmitriptan among other currently or soon to be available selective 5-HT1B/1D receptor agonists. However, on the basis of available data, zolmitriptan should emerge as a useful treatment option in the management of patients with moderate to severe migraine.

Tolterodine.

Tolterodine is a competitive muscarinic receptor antagonist which has recently been launched for the treatment of overactive bladder. Tolterodine shows functional selectivity for the bladder over the salivary glands in vivo, which is not attributable to muscarinic receptor subtype selectivity. It is as potent as oxybutynin in inhibiting bladder contraction, but is much less potent in inhibiting salivation, suggesting that it may have less propensity to cause dry mouth in clinical use. In patients with overactive bladder, toleterodine significantly reduces the frequency of micturition and number of incontinence episodes, while increasing the average volume voided. The onset of pharmacological action of tolterodine is < 1 hour and therapeutic efficacy is maintained during long term treatment. In comparative trials, tolterodine and oxybutynin are equivalent in terms of efficacy. However, tolterodine is significantly better tolerated than oxybutynin, particularly with respect to the incidence and severity of dry mouth. No clinically relevant ECG changes have been noted with tolterodine.

Symptomatic improvement in achalasia after botulinum toxin injection of the lower esophageal sphincter.

OBJECTIVES: The aim of this study was to assess the long term clinical outcome of patients with achalasia after treatment with botulinum toxin. METHODS: Sixty five patients with achalasia (60 idiopathic, five secondary) were treated with injection of botulinum toxin at the gastroesophageal junction. Dysphagia, chest pain, and regurgitation were scored (0 = no symptoms, 1 = mild, 2 = moderate, 3 = severe, 4 = very severe), with the sum representing the total symptom score, at 0, 7, 30, 120, 240, and 365 days posttreatment. Responders were defined as patients with a 50% decrease in total symptom score at 1 month posttreatment. RESULTS: The 60 patients with idiopathic achalasia had significant improvement in symptoms of dysphagia, chest pain, and regurgitation at 1 and 4 wk posttreatment. At 1 month posttreatment, 42 of 60 patients (70%) were classified as responders. Of 33 patients with at least 1 yr follow-up, 36% continued to have a good or excellent response, whereas 39% underwent a subsequent treatment with botulinum toxin, pneumatic dilation, or myotomy. When symptoms recurred after an initial response, patients responded to a second injection of botulinum toxin in six of seven cases. In four of five patients with secondary achalasia, there was no response to botulinum toxin. CONCLUSIONS: Botulinum toxin injection at the gastroesophageal junction significantly improved symptoms in 70% of patients with idiopathic achalasia at 1 month. Recurrent symptoms responded to repeat botulinum toxin treatment in initially responsive patients. In contrast, most patients with secondary achalasia did not improve after botulinum toxin injection.

Soft X-Ray Contact Microscopy of Biological Specimens: Aluminum-Coated Silicon Nitride Windows as XUV Filters.

The optimum wavelengths for soft x-ray contact microscopy of biological specimens are between 2.2 and 4.4 nm as, relative to water, this gives maximum contrast between carbon- and oxygen-containing constituents. Irradiation outside of this so-called "water window" interferes with either the resolution and/or the contrast that can be obtained. The previous belief that silicon nitride windows act as an effective filter for the longer wavelength, XUV radiation generated from laser-produced plasmas is shown to be suspect. However, in this study the use of aluminum-coated windows, which effectively exclude these longer wavelengths, still permits successful imaging of biological specimens. The added strength imparted to coated windows also ensures their survival during the imaging process, thereby demonstrating that the tissues can remain hydrated at the time that the image is formed in the photosensitive resist material used in this technique.

Biological properties of ten human ovarian carcinoma cell lines: calibration in vitro against four platinum complexes.

Ten human ovarian carcinoma cell lines have been studied as a potential in vitro screen for the development of novel anticancer platinum complexes. Lines have been established and developed both from solid and ascitic tumours, from pretreated and untreated patients, and are available at a range of in vitro passage numbers. The biological properties of the lines were consistent with them being human, epithelial and of ovarian carcinoma origin. Using a tritiated thymidine or leucine uptake method, and a 96 hour continuous drug exposure, the lines have been calibrated against four platinum-containing chemotherapeutic agents: cisplatin, iproplatin, carboplatin and tetraplatin. Striking differences in cytotoxicity were observed across the lines for each agent. Some lines were consistently resistant, others generally sensitive, whereas some showed clear evidence of differential sensitivity to a particular agent. Statistical analysis (Spearman rank correlation) involving the six possible pairings of drugs showed that cisplatin, iproplatin and carboplatin elicit a very similar pattern of response in these lines whereas tetraplatin elicits a completely different response pattern. Similar cytotoxicity values were obtained using a soft agar cloning assay. Results using a tetrazolium dye reduction assay, however, gave somewhat higher and more variable values, particularly with tetraplatin. The thymidine uptake assay will be adopted in further studies on a selected panel of six lines. This panel encompasses the spectra of sensitivities identified for each of the four agents against the original ten lines and may provide a useful screening facility for the development of novel platinum drugs, in that it detects both cell line-determined and structure-determined differences in cytotoxicity.