[Corneal biomechanics before and after cross-linking in patients with keratoconus]. / Die Biomechanik der Hornhaut vor und nach Crosslinking bei Patienten mit Keratokonus.

OBJECTIVE: The aim of this study was to analyze the effect of corneal cross-linking (CXL) on corneal biomechanics and visual acuity. PATIENTS AND METHODS: The examination results before and after CXL in 56 eyes of 56 patients between 2017 and 2021 were evaluated retrospectively. The last preoperative examination was compared to the postoperative follow-up values after 6 and 12 months. The main outcome measures included various biomechanical parameters from the Corvis ST (CST), Pentacam and the visual acuity (logMAR, "logarithm of the Minimal Angle of Resolution"). For longitudinal evaluation, a general linear model for repeated measurements was used. A p-value of less than 0.05 was considered to show a statistically significant result. Bonferroni correction was applied for multiple comparisons. RESULTS: The maximum corneal refractive power Kmax decreased slightly without statistical significance from 57.1 ± 6.1 diopters (dpt) to 56.6 ± 6.3 dpt after 6 months (p = 0.076) and 56.8 ± 6.6 dpt after 12 months (p = 0.443). The Pentacam parameter Belin/Ambrósio Enhanced Ectasia Total Deviation Display (BAD D) showed a statistically significant increase from the preoperative value of 8.4 ± 3.7 to the postoperative value of 9.1 ± 3.6 after 6 months (p < 0.001) and to 8.9 ± 3.5 after 12 months (p = 0.051). The CST parameter Ambrósio's relational thickness to horizontal profile (ARTh) decreased statistically significantly from 229.9 ± 109.6 to 204.8 ± 84.9 at 6 months (p = 0.017) and 205.3 ± 93.7 at 12 months (p = 0.022). The CST parameter stiffness parameter A1 (SP A1) increased slightly from the preoperative value 69.9 ± 17.2 to 70.4 ± 17.2 after 6 months (p = 1) and 71 ± 18.2 after 1 year (p = 1). Mean best-corrected visual acuity (logMAR) showed an improvement from 0.39 ± 0.3 to 0.34 ± 0.3 at 6 months (p = 0.286) and to 0.31 ± 0.3 at 12 months (p = 0.077). Regarding the ABCD classification, the parameters were determined preoperatively with an average of A2B3C1D2. They showed the same value of A2B3C1D2 after 6 and 12 months. CONCLUSION: In progressive keratoconus, corneal cross-linking has the potential to positively influence the biomechanics of the cornea and visual acuity as a low complication treatment option.

Glomerular mRNAs in human type 1 diabetes: biochemical evidence for microalbuminuria as a manifestation of diabetic nephropathy.

BACKGROUND: In patients with type 1 diabetes, some consider microalbuminuria to be a predictor of diabetic nephropathy while others believe it is an early feature of diabetic nephropathy. METHODS: Levels of mRNAs that are of pathogenetic relevance in diabetic nephropathy were compared in glomeruli isolated from microalbuminuric and overtly proteinuric subjects and in control normoalbuminuric diabetic subjects and living renal transplant donors. RESULTS: In subjects with microalbuminuria and overt proteinuria, glomerular mRNAs were virtually identical and approximately twofold higher for connective tissue growth factor (CTGF; P < 0.01) and collagen alpha2(IV) (P < 0.03) compared to living renal donors and normoalbuminuric patients. Glomerular glyceraldehyde-3-phosphate dehydrogenase (GAPDH) levels were not significantly different among the groups (P = 0.4). Weak but statistically significant correlations were noted between CTGF mRNA and albuminuria (assessed by rank), fractional mesangial surface area, and a composite renal biopsy index. Glomerular CTGF mRNA correlated inversely with creatinine clearance. Glomerular collagen alpha2(IV) mRNA levels correlated with albuminuria (by rank) and less strongly with fractional mesangial area. CONCLUSION: To our knowledge, these data provide the first biochemical evidence demonstrating that the glomeruli of microalbuminuric patients and those with overt proteinuria do not differ significantly. The data support the concept that microalbuminuria is not "predictive" of diabetic nephropathy, but rather is an earlier point in the spectrum of diabetic nephropathy.

Irritable bowel syndrome in twins: heredity and social learning both contribute to etiology.

BACKGROUND & AIMS: Heredity has been suggested to explain the finding that irritable bowel syndrome (IBS) tends to run in families. Research in this area has been limited. The aim of the present study was to assess the relative contribution of genetic and environmental (social learning) influences on the development of IBS by comparing concordance rates in monozygotic and dizygotic twins to concordance between mothers and their children. METHODS: Questionnaires soliciting information on the occurrence of more than 80 health problems, including IBS, in self and other family members were sent to both members of 11,986 twin pairs. RESULTS: Analysis is based on 10,699 respondents representing 6060 twin pairs. Concordance for IBS was significantly greater (P = 0.030) in monozygotic (17.2%) than in dizygotic (8.4%) twins, supporting a genetic contribution to IBS. However, the proportion of dizygotic twins with IBS who have mothers with IBS (15.2%) was greater than the proportion of dizygotic twins with IBS who have co-twins with IBS (6.7%, P < 0.001), and logistic regression analysis showed that having a mother with IBS and having a father with IBS are independent predictors of irritable bowel status (P < 0.001); both are stronger predictors than having a twin with IBS. Addition of information about the other twin accounted for little additional predictive power. CONCLUSIONS: Heredity contributes to development of IBS, but social learning (what an individual learns from those in his or her environment) has an equal or greater influence.

An Association Between Varying Degrees of Hypothyroidism and Hypercholesterolemia in Women: The Thyroid-Cholesterol Connection.

Evidence of an association between subclinical hypothyroidism and cardiovascular disease is mounting. The impact of thyroid hormone on lipid levels is primarily mediated through triiodothyronine (T(3))-bound thyroid protein binding and activation of the promoter regions of the low-density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A-reductase genes, leading to a reduction in serum cholesterol levels. Thus, the decreased T(3) seen in hypothyroidism may result in increased serum cholesterol. Although a clear correlation exists between overt hypothyroidism and clinically significant hypercholesterolemia, there is a logarithmic relationship between thyroid-stimulating hormone and cholesterol, and the effects of subclinical hypothyroidism on cardiovascular disease are under debate. However, current data suggest that normalizing even modest thyroid-stimulating hormone elevations may result in improvement in the lipid profile. (c)2001 CHF, Inc.

Glomerular type IV collagen in patients with diabetic nephropathy with and without additional glomerular disease.

BACKGROUND: Type IV collagen is a constituent of mesangial matrix and is increased in amount in many forms of glomerular injury. METHODS: We performed renal biopsies in patients who (1) were donating a kidney to a relative (LRD, N = 6), (2) had diabetic glomerulopathy with or without nephrosclerosis (DM, N = 6), or (3) had diabetic glomerulopathy with a superimposed glomerular lesion (DM+, N = 5). Glomerular collagen alpha2(IV) and control glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNAs were measured, and the former correlated with clinical and morphological data to assess its usefulness in reflecting glomerular injury. RESULTS: Collagen alpha2(IV) mRNA levels were lowest in LRD (2.9 +/- 0.6 attomol/glomerulus), higher in DM (5.9 +/- 1.6, P = 0.05), and highest in DM+ (12.7 +/- 2.8 attm/glomerulus, P < 0.05 vs. LRD and vs. DM). Control GAPDH mRNA levels were not significantly different (P > 0.05). Levels of proteinuria, serum creatinine, and glomerular size did not correlate with collagen alpha2(IV) mRNA levels. The fractional mesangial area and the fractional mesangial area occupied by type IV collagen were higher in both diabetic groups than in LRD (P < 10-6), but the intensity of type IV collagen staining in the diabetic patients was significantly less than that seen in the LRD (P < 0.01). In DM+ patients, extramesangial type IV collagen was present. Fractional mesangial area and glomerular collagen alpha2(IV) mRNA levels correlated (r = 0.45, P < 0.05). CONCLUSION: These data are consistent with a view of diabetic nephropathy as a lesion of increased alpha2 type IV collagen transcription, increased total amount of collagen present, but decreased mesangial density relative to other matrix molecules. These data further demonstrate that glomerular injury superimposed on diabetic nephropathy contributes to additional structural damage by inducing increased synthesis of type IV collagen at extramesangial sites.

Changing trends in patient decisions concerning genetic amniocentesis.

OBJECTIVE: This study was undertaken to determine whether there was a change in patient decisions concerning genetic amniocentesis during the period 1995-1998. STUDY DESIGN: All patients referred for genetic counseling because of advanced maternal age, abnormal serum triple-screen results, or ultrasonographic abnormalities between January and March 1995 and between January and March 1998 were evaluated through a retrospective chart review. Patient characteristics included age, race, and gestational age. Group 1 consisted of patients from 1995. Group 2 consisted of patients from 1998. Data on patient decisions concerning amniocentesis before and after genetic counseling and ultrasonographic examination were compared in each group. Groups 1 and 2 were then compared with respect to decisions before and after genetic counseling and ultrasonographic evaluation. RESULTS: A total of 112 patients were studied. Group 1 consisted of 53 patients and group 2 consisted of 59 patients. When the groups were compared, no differences in age, race, or gestational age were noted. In group 1, before counseling, 18 of 53 patients desired genetic testing, compared with 44 of 53 after counseling (P =.02). In group 2, before counseling, 4 of 59 patients desired genetic testing, compared with 15 of 59 after counseling (P =.01). A significantly greater number of patients in group 1 than in group 2 desired genetic testing both before counseling (n = 18/53 vs n = 4/59; P =.01) and after counseling (n = 44/53 vs n = 15/59; P =.01). CONCLUSION: Fewer patients at risk for Down syndrome in 1998 than in 1995 desired amniocentesis both before and after genetic counseling and ultrasonographic examination.

Active population growth and immigration hypotheses in Western Europe.

The paper examines, in respect of 12 Western European countries over a period of 20 years, the widely held view that any decline in their working population should be offset by greater reliance on immigrant labor. This research, based on demographic projections and forecasts regarding labor market participation rates by age and sex for each of the countries concerned, focuses on the two most likely scenarios. It appears that only Italy will be faced with a fall in its working population. All other western countries will either maintain the same level or, more generally, see their workforce grow substantially. Accordingly, the authors may safely assert that there is no risk of a shortage of workers between now and the year 2020, and that an increasing supply of labor will render reliance on a greater influx of immigrant workers unnecessary. The second part analyses changes in the structure of the demand for labor. The authors deal chiefly with the phenomenon of the concentration of foreign manpower in each sector, its flexibility and mobility in a context of unemployment, as well as the impact of new technologies and globalization on the main determinants of international migration of labor.

Altered VH6-D-JH repertoire in human insulin-dependent diabetes mellitus and autoimmune idiopathic thrombocytopenic purpura.

We have characterized the peripheral B cell repertoire in T cell-mediated insulin-dependent diabetes mellitus (IDMM) and in B cell-mediated autoimmune idiopathic thrombocytopenic purpura (AITP). The VH6-containing repertoire in adult patients with IDDM or AITP and healthy control subjects was investigated by PCR amplification using VH6- and JH-specific primers. Nucleotide sequence analysis of VH6-D-JH rearrangements showed an abnormally high frequency of somatic mutations in non-functional rearrangements from diabetic (3. 58 %) as well as AITP patients (3.18 %), compared to controls (0.4 % and 1.43 %, respectively; p < 0.05). In contrast, the mutation frequency among functional rearrangements was 2.4 - 3 times lower in patients compared to controls ( p < 0.05). Detailed analysis of the VH6 genes carrying mutations showed that the underlying mechanism for this observation is probably different for the two diseases. Analysis of D- and JH gene usage revealed additional deviations from the normal pattern. Taken together, these results suggest defects in the mechanisms controlling selection of the B cell repertoire in patients with IDDM or AITP.

Increased utilization of the VH6 gene family in patients with autoimmune idiopathic thrombocytopenic purpura.

The VH gene family utilization pattern among pokeweed mitogen-stimulated immunocompetent B cells (available repertoire) and naturally activated B cells (actual repertoire) from the spleen was analysed in a group of patients with autoimmune idiopathic thrombocytopenic purpura (AITP). For this purpose a non-radioactive RNA in situ hybridization technique was employed, allowing detection of VH gene family expression in single cells. The results show that the VH gene family expression pattern in patients with AITP does not correlate with genomic complexity of the VH genes. Furthermore, the pattern of VH gene family utilization in AITP patients is statistically different from that of healthy controls in the available, but not in the actual repertoire. The VH5 gene family is used at a frequency of 11.3% in patients' resting B lymphocytes, compared to 23.9% in controls. The VH6 gene family is used more frequently in patients (23.0% compared to 3.8% in controls). The increase in VH6 gene expression is not reflected in the actual repertoire, where the frequency of expression is 6.4%, and can therefore not be directly related to the presence of disease specific autoantibodies.

Plasmapheresis in the treatment of steroid-resistant focal segmental glomerulosclerosis in native kidneys.

A circulating glomerular capillary albumin permeability factor (P(alb)) has been implicated in the pathogenesis of focal segmental glomerulosclerosis (FSGS), which recurs in transplanted kidneys. Plasmapheresis for recurrent FSGS may reduce proteinuria and stabilize renal function if instituted early. We performed six plasmapheresis treatments over 2 weeks in eight patients with a history of steroid-resistant idiopathic FSGS in native kidneys for an average of 12 +/- 2.3 months to determine whether treatment would decrease proteinuria or stabilize renal function. P(alb) was measured before and after plasmapheresis, and patients were followed-up for a mean of 29 +/- 4 months after the development of clinical symptoms. Proteinuria decreased in two of eight treated patients, although only transiently in one of the two. P(alb) improved in one of the two responding patients. Both patients with an improvement in proteinuria had stable renal function at last follow-up. In six of eight patients, there was no improvement in proteinuria despite an improvement in P(alb) (P < 0.0001) after plasmapheresis. At last follow-up, renal function was stable in two of the six nonresponding patients, and four of the six had significant progression of renal disease or were receiving dialysis treatments. These studies suggest that plasmapheresis may diminish proteinuria and stabilize renal function in a small minority of patients with steroid-resistant idiopathic FSGS. However, the lack of a relationship between the removal of the circulating permeability factor and the development of remission in these patients suggests that local factors associated with advanced renal injury or systemic factors unrelated to glomerular permeability play a significant role in determining proteinuria at this late stage of the disease.

Mast cells enhance eosinophil survival in vitro: role of TNF-alpha and granulocyte-macrophage colony-stimulating factor.

Mast cell-eosinophil interactions in allergy have not yet been completely defined. To determine whether mast cells influence eosinophil survival, human peripheral blood eosinophils were incubated with rat peritoneal mast cell sonicate. After 3 days, viable eosinophils in medium were 21.3% compared with 44% with mast cell sonicate. Like sonicate, supernatants of compound 48/80-activated mast cells enhanced eosinophil survival, demonstrating that the factor(s) involved is stored preformed and rapidly released. Increased eosinophil survival was due to an inhibition of apoptosis (morphologic analysis; annexin V/PI). Neutralizing Abs to granulocyte-macrophage CSF (GM-CSF), but not to IL-3 or IL-5, decreased by 61.7% the enhancing effect on eosinophil viability. Eosinophils are the source of GM-CSF since its release in the culture medium was inhibited by their incubation with the mast cell sonicate together with dexamethasone. In addition, eosinophils incubated with the sonicate expressed mRNA for GM-CSF. To partially characterize the mast cell-derived factor(s) increasing eosinophil survival, the sonicate was heated (56 degrees C/30 min or 100 degrees C/10 min) or preincubated with antihistamines or with anti-TNF-alpha-neutralizing Abs. Most of the activity was heat labile. TNF-alpha was found to be predominantly (70%) responsible, while histamine had no role. Mast cell sonicate also caused eosinophils to release eosinophil peroxidase and to display morphologic signs of activation. In conclusion, we have demonstrated that mast cells enhance eosinophil survival in part through their activation to produce and release the autocrine survival cytokine GM-CSF.

First international new intravascular rigid-flex endovascular stent study (FINESS): clinical and angiographic results after elective and urgent stent implantation. The FINESS Trial Investigators.

OBJECTIVES: The purpose of this study was to determine the feasibility, safety and efficacy of elective and urgent deployment of the new intravascular rigid-flex (NIR) stent in patients with coronary artery disease. BACKGROUND: Stent implantation has been shown to be effective in the treatment of focal, new coronary stenoses and in restoring coronary flow after coronary dissection and abrupt vessel closure. However, currently available stents either lack flexibility, hindering navigation through tortuous arteries, or lack axial strength, resulting in suboptimal scaffolding of the vessel. The unique transforming multicellular design of the NIR stent appears to provide both longitudinal flexibility and radial strength. METHODS: NIR stent implantation was attempted in 255 patients (341 lesions) enrolled prospectively in a multicenter international registry from December 1995 through March 1996. Nine-, 16- and 32-mm long NIR stents were manually crimped onto coronary balloons and deployed in native coronary (94%) and saphenous vein graft (6%) lesions. Seventy-four percent of patients underwent elective stenting for primary or restenotic lesions, 21% for a suboptimal angioplasty result and 5% for threatened or abrupt vessel closure. Fifty-two percent of patients presented with unstable angina, 48% had a previous myocardial infarction, and 45% had multivessel disease. Coronary lesions were frequently complex, occurring in relatively small arteries (mean [+/-SD] reference diameter 2.8 +/- 0.6 mm). Patients were followed up for 6 months for the occurrence of major adverse cardiovascular events. RESULTS: Stent deployment was accomplished in 98% of lesions. Mean minimal lumen diameter increased by 1.51 +/- 0.51 mm (from 1.09 +/- 0.43 mm before to 2.60 +/- 0.50 mm after the procedure). Mean percent diameter stenosis decreased from 61 +/- 13% before to 17 +/- 7% after intervention. A successful interventional procedure with < 50% diameter stenosis of all treatment site lesions and no major adverse cardiac events within 30 days occurred in 95% of patients. Event-free survival at 6 months was 82%. Ninety-four percent of surviving patients were either asymptomatic or had mild stable angina at 6 month follow-up. CONCLUSIONS: Despite unfavorable clinical and angiographic characteristics of the majority of patients enrolled, the acute angiographic results and early clinical outcome after NIR stent deployment were very promising. A prospective, randomized trial comparing the NIR stent with other currently available stents appears warranted.

Infrapopliteal transcatheter interventions for limb salvage in diabetic patients: importance of aggressive interventional approach and role of transcutaneous oximetry.

OBJECTIVES: This study sought to determine whether infrapopliteal transcatheter interventions can salvage ischemic limbs in diabetic patients referred for below the knee amputation at our institution. BACKGROUND: The value of transcatheter interventions in diabetic crural arteries is controversial. Tissue oxygen partial pressure (TCO2) levels < 40 mm Hg predict poor wound healing. METHODS: Percutaneous interventions were performed in 29 consecutive diabetic patients in need of limb salvage. Technical success was defined as < 20% residual vessel stenosis. Clinical success was defined as the avoidance of amputation and achievement of wound healing. At hospital discharge, patients were treated with Coumadin and aspirin. Ankle-brachial index (ABI) and TCO2 measurements were obtained before and after the intervention. RESULTS: After 12-month follow-up, six patients had presistent wounds, whereas 23 experienced wound healing. Forty of the 50 infrapopliteal arteries successfully dilated were occluded, with a mean (+/-SD) lesion length of 18.0 +/- 3.5 cm. After the procedure, TCO2 improved from 27.82 +/- 9.97 mm Hg (95% confidence interval [CI] 23.95 to 31.69) to 54.5 +/- 14.73 mm Hg (95% CI 48.79 to 60.21, p < 0.0001), whereas the ABI did not (p > 0.2). TCO2 predicted procedural and clinical success (p < 0.0182). CONCLUSIONS: Infrapopliteal transcatheter interventions in diabetic patients may salvage the majority of limbs doomed to amputation. Although TCO2 measurements are valuable in predicting wound healing and success after interventions, ABI measurements are not.

Database filter: optoelectronic design and implementation.

The results of a successful demonstration of the selection module of an optoelectronic parallel-processing database filter is presented. The module utilizes 4 x 4 arrays of AND and XOR logic gates that respectively perform the functions of reducing the data fields and determining a match between the input data and a selection argument. The logic arrays were fabricated with InGaP/GaAs heterojunction phototransistors that drive vertical-cavity surface-emitting lasers (VCSEL's). The VCSEL's provide the free-space optical interconnection between stages. The design of the system and the optical power budget are discussed.

Age-related impaired affinity maturation and differential D-JH gene usage in human VH6-expressing B lymphocytes from healthy individuals.

To elucidate the basic molecular events underlying humoral immunity during ontogeny and senescence, we analyzed a panel of 179 polymerase chain reaction-derived VH6-D-JH rearrangements from cord blood, peripheral blood, and spleen. Nucleotide sequence analysis of the CDR3 region shows that there is a difference in D and JH gene usage in functional rearrangements between lymphocytes from peripheral blood and spleen. Analysis of the VH6 gene shows that the mutational frequencies rise from 0.81% in cord blood to 1.96% in peripheral blood lymphocytes derived from young adults, and decrease to 0.80% in samples from individuals older than 50 years. The number of rearrangements carrying mutations follows a similar pattern: 22% in cord blood, 73% in the age group 20-49 years, and 57% in the age group over 50 years. The mutational frequencies among the mutated genes are, however, similar for cord blood and young adults, 2.76% and 2.51%, respectively, and 1.3% in older adults. These data show an age-related impaired affinity maturation which might relate to the decrease in immunological responsiveness among the elderly.

Aberrant V(H) gene utilization in patients with established insulin dependent diabetes mellitus.

We have compared the B-lymphocyte repertoire in seven IDDM patients with 12 healthy controls by examining the variable heavy (V(H)) gene expression. The V(H) gene representation in the pool of pokeweed mitogen (PWM) stimulated, immunocompetent B cells and in the pool of naturally activated plasma cells (actual repertoire) was analysed by RNA-RNA in situ hybridization. Differences between IDDM patients and normal controls in the relative expression of several V(H) gene families were observed. In IDDM patients, the V(H)3 was significantly underrepresented in the PWM stimulated repertoire. In the actual B cell repertoire the V(H)5 clones were underrepresented among diabetic patients. Moreover, the altered distribution of V(H) gene usage between the PWM stimulated repertoire and the actual repertoire observed in normal controls was found to be less pronounced in the IDDM patients. This observation suggests a defect in the V-gene directed cellular selection occurring between resting, immunocompetent B cells and naturally activated plasma cells. The possible implication of the observed aberrations in the B cell selection process for the pathogenesis of autoimmunity is discussed.

The effect of transfection of antisense cDNA for procollagen alpha 1 (IV) on stimulated proliferation in rat glomerular endothelial cells.

Glomerular endothelial cells were stably transfected with a pMAMneo-Blue vector recombinant for procollagen alpha 1 (IV) cDNA in the sense (S) or antisense (AS) orientation utilizing a calcium phosphate precipitation technique. Cellular clones resistant to G418 antibiotic were selected and expanded for further analysis. Immunofluorescence microscopy demonstrated less Type IV collagen in the AS clones (1.0 +/- 0.3) than in control parent (P) and S clones (2.0 +/- 0.4) (P < 0.05). Western analysis showed that the AS clones synthesized 20 +/- 10% of the 205-kd alpha 1 (IV) chain of Type IV collagen compared with P cells (P < 0.05). As transfected clones demonstrated similar basal proliferation rates as control cells when cultured in 0.5% fetal calf serum (FCS), but failed to undergo fetal calf serum (FCS)-stimulated hyperplasia when grown on standard fibronectin-coated surfaces in 40% FCS (P < 0.05, compared with P- and S-transfected control cells). There were significant linear relationships between the presence of Type IV collagen as detected by either immunofluorescence microscopy or alpha 1 (IV) peptide chain quantitation by Western analysis and the ability of cells to undergo FCS-stimulated hyperplasia when grown on fibronectin (P < 0.05). Growth on a surface comprised of fibronectin plus Type IV collagen restored the capacity of AS transfected cells to respond to FCS stimulation (P < 0.001), but had no significant effect on the proliferative behavior of P or S cells. Measurements of AS RNA levels in these cells suggest that the inhibition of stimulated proliferation is determined by the presence of a threshold quantity of cellular AS RNA. These data demonstrate that Type IV collagen plays a critical role in conditioning glomerular endothelial cells to respond to proliferative stimuli.

Apoptosis in mesangial cells induced by ionizing radiation and cytotoxic drugs.

Mesangial proliferation contributes to the pathogenesis of many forms of glomerulonephritis. To evaluate the role of apoptosis on the pharmacologic effects of cytotoxic drugs and ionizing radiation, we studied their effects on cultured rat mesangial cells (MC), whose apoptotic response to these drugs is unknown. Mesangial cells were cultured with or without stimuli to induce apoptosis and were harvested at 24 and 48 hours. MC morphology was examined by light microscopy, in situ end labeling technique using terminal deoxy-transferase (TUNEL) and by electrophoresis of extracted total cellular DNA. MCs exposed to cytotoxic drugs or irradiation demonstrated statistically significant increases in apoptotic cells identified by light microscopy. DNA fragmentation of apoptotic cells was also visualized as characteristic staining by the TUNEL method and statistically significant increases in apoptotic cell number in cells exposed to cytotoxic drugs and irradiation were noted compared to control cultures. In general, the number of TUNEL positive cells was greater than that of morphologically apoptotic cells. DNA extracted from these cells also showed the characteristic ladder pattern of internucleosomal chromatin cleavage of 180 bp fragments on agarose gel electrophoresis. To further analyze whether MC apoptosis induced by these drugs alters the cell cycle, 3H-thymidine incorporation rates were measured in both the cell culture monolayer and in those cells shed into the supernatant when cultured with or without cyclophosphamide (N = 5). 3H-thymidine incorporation corrected for total cellular DNA showed a similar pattern in both control and cyclophosphamide treated groups, suggesting that cyclophosphamide did not alter the mesangial cell cycle. Considering that the dosage of the cytotoxic drugs utilized in these experiments in nearly the therapeutic plasma level in humans, these results suggest that cytotoxic drugs used to treat glomerular disease can induce apoptotic mesangial cell death and may operate in part via this mechanism.