PubMed Health⌕ Search

Biomedical subjects

L C Racusen

Publications and source records attributed to L C Racusen.

At least 19 recordsLinked to original sources
PubMed2001

Cohort study of the prognostic significance of acute transplant glomerulitis in acutely rejecting renal allografts.

BACKGROUND: Acute transplant glomerulitis is a unique lesion in renal allografts, the prognostic significance of which is controversial. We conducted this retrospective cohort study to examine the independent prognostic significance of moderate-to-severe transplant glomerulitis in acute rejection. METHODS: Renal allograft survival for patients with acute rejection were studied, comparing one group with significant glomerulitis (G, n=28) with those with no glomerulitis (NG, n=35). Clinical, biopsy, and demographic data and renal graft survival were compared, and the association of G with graft failure was examined. RESULTS: In the G versus NG group, a greater percentage of patients were highly sensitized (peak panel reactive antibody value >80%; P=0.009), had had a previous renal transplant (40% vs. 11%; P=0.02), or had suffered from delayed graft function (P=0.03). The G group had a trend toward earlier rejection episodes (P=0.07), a significantly higher serum creatinine at the time of index biopsy (P=0.01), a higher prevalence of vascular rejection (P=0.02), and less improvement in mean reciprocal serum creatinine at 1-2 weeks after biopsy (P=0.02). Although there was a trend toward shorter allograft survival in the G group (P=0.09), the level of significance of which increased with adjustment for transplantation time period and the duration of the transplant-biopsy interval (P=0.06), the relative risk for graft loss was no longer significant when additionally adjusted for index biopsy Banff score (relative risk, 0.97; P=0.97). CONCLUSION: In this study, G was significantly more common in highly sensitized patients and was strongly associated with vascular rejection biopsies but was not an independent predictor of graft survival.

Acute Disease↗
PubMed2001

Effect of Bw4 and Bw6 epitope mismatches on antibody production, acute and chronic rejection, and graft survival in renal allografts.

BACKGROUND: Highly sensitized patients often have antibodies directed against the HLA Bw4 and Bw6 epitopes. Because of the high frequency of these epitopes, when present, these antibodies result in a high incidence of positive cross-matches. We sought to determine whether antibodies specific for Bw4 or Bw6 affected renal allograft outcome. METHODS: The effect of mismatches for the HLA class I public epitopes, Bw4 and Bw6, was examined in 72 recipients of one haplotype matched recipients of living, related donor renal allografts selected to control for degree of HLA mismatch. Analysis of the production of HLA-specific antibody was performed for 180 recipients of failed cadaveric allografts by complement-dependent cytotoxicity tests and by an enzyme-linked immunoadsorbent assay (ELISA). RESULTS: No significant difference was observed in the incidence of acute rejection, number of rejection episodes or 1-year allograft survival among Bw4/6 matched versus mismatched recipients of one haplotype matched allografts. Additionally, no significant difference in the development of chronic allograft nephropathy was noted among 56 recipients followed long-term (> or =3 years). In the recipients of failed cadaveric transplants, Bw4/6 mismatching was associated with the frequency and magnitude of production of HLA-specific antibody. However, the panel reactive antibodies correlated with the number of HLA-A and -B mismatches, and there was no additional impact of Bw4/6 mismatching. IgG, HLA-specific antibodies were found to be significantly increased among patients homozygous for Bw4 or Bw6, whether or not there was a Bw4/6 mismatch. CONCLUSIONS: Mismatching for Bw4 or Bw6 does not confer any independent, increased risk for humoral sensitization or renal allograft failure.

Acute Disease↗
PubMed2000

Plasmapheresis and intravenous immune globulin provides effective rescue therapy for refractory humoral rejection and allows kidneys to be successfully transplanted into cross-match-positive recipients.

BACKGROUND: Hyperacute rejection (HAR) and acute humoral rejection (AHR) remain recalcitrant conditions without effective treatments, and usually result in graft loss. Plasmapheresis (PP) has been shown to remove HLA- specific antibody (Ab) in many different clinical settings. Intravenous gamma globulin (IVIG) has been used to suppress alloantibody and modulate immune responses. Our hypothesis was that a combination of PP and IVIG could effectively and durably remove donor-specific, anti-HLA antibody (Ab), rescuing patients with established AHR and preemptively desensitizing recipients who had positive crossmatches with a potential live donor. METHODS: The study patients consisted of seven live donor kidney transplant recipients who experienced AHR and had donor-specific Ab (DSA) for one or more mismatched donor HLA antigens. The patients segregated into two groups: three patients were treated for established AHR (rescue group) and four cross-match-positive patients received therapy before transplantation (preemptive group). RESULTS: Using PP/IVIG we have successfully reversed established AHR in three patients. Four patients who were cross-match-positive (3 by flow cytometry and 1 by cytotoxic assay) and had DSA before treatment underwent successful renal transplantation utilizing their live donor. The overall mean creatinine for both treatment groups is 1.4+/-0.8 with a mean follow up of 58+/-40 weeks (range 17-116 weeks). CONCLUSIONS: In this study, we present seven patients for whom the combined therapies of PP/IVIG were successful in reversing AHR mediated by Ab specific for donor HLA antigens. Furthermore, this protocol shows promise for eliminating DSA preemptively among patients with low-titer positive antihuman globulin-enhanced, complement-dependent cytotoxicity (AHG-CDC) cross-matches, allowing the successful transplantation of these patients using a live donor without any cases of HAR.

Adult↗
PubMed2000

Intracellular pH regulatory mechanism in a human renal proximal cell line (HKC-8): evidence for Na+/H+ exchanger, CI-/HCO3- exchanger and Na+-HCO3- cotransporter.

In the present study we investigated whether an immortalized human renal proximal cell line, HKC-8, expresses a recently cloned Na+-HCO3- cotransporter (NBC-1) and, if so, which isoform (kNBC-1 from kidney or pNBC-1 from pancreas) is expressed in this cell line. Cell pH (pHi) measurements using a pH-sensitive fluorescence probe in the absence of HCO3-/CO2 revealed the presence of a Na+/H+ exchanger that required high concentrations of amiloride for full inhibition. In the presence of HCO3-/CO2 another pHi recovery process, dependent on Na+ but independent of Cl-, was identified. This process was electrogenic and was inhibited by 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulphonic acid (DIDS), being consistent with the Na+-HCO3- cotransporter. In addition, the pHi responses to Cl- removal were compatible with the presence of a Na+-independent Cl-/HCO3- exchanger that was also inhibited by DIDS. Reverse transcriptase polymerase chain reaction (RT-PCR) using primers designed for specific and common regions detected mRNAs of both kNBC-1 and pNBC-1 and Western blot analysis confirmed the expression of NBC-1 protein. These results indicate that HKC-8 has transport activities similar to intact proximal tubules and also suggest that both kNBC-1 and pNBC-1 may contribute to the Na+-HCO3- cotransport activity in this cell line.

Acids↗
PubMed1999

Plasma cell-rich acute renal allograft rejection.

BACKGROUND: Acute renal allograft rejection is usually seen within the first 3 months posttransplant, and is characterized by an intense infiltrate of T cells. Some acute rejections, however, contain many plasma cells and/or appear late posttransplant. METHODS: We have investigated 27 cases of intensely plasma cell-rich acute rejections (PCAR) from 1987 to 1997 and have compared them to 21 control cases (CAR) of typical acute rejection. Each group was divided into early (<6 months) and late (>6 months) subgroups. PCAR and CAR cases were matched for histological features of chronic allograft nephropathy. In all four groups, most cases had Banff '97 type IB and IIA acute rejection. RESULTS: A significantly greater number of PCAR cases experienced graft failure due to chronic allograft nephropathy or complications of acute rejection (P<0.05). There was no significant difference between PCAR and CAR in HLA matching, occurrence of posttransplant acute tubular necrosis, presence versus absence of previous allografts, number of previous or subsequent acute rejection episodes, Banff '97 sum scores for acute rejection, cyclosporine A or FK506 levels, or percent change from baseline creatinine at time of biopsy. Plasma cells in PCAR cases showed IgG predominance whereas those in CAR had comparable staining for IgG and IgA. Kappa and lambda light chain immunostaining of all PCAR cases revealed polyclonality. Three of 18 PCAR cases studied for the presence of Epstein-Barr virus RNA showed scattered positivity in 2-7% of lymphoid cells, although the remainder was negative. None of the PCAR cases developed post-transpland lymphoproliferative disorder. CONCLUSIONS: We conclude that PCAR can occur from 1 month to many years posttransplant, is associated with poor graft survival, and is not a manifestation of concomitant chronic allograft nephropathy or viral infection, including posttransplant lymphoproliferative disorder.

Acute Disease↗
PubMed1999

Chronic aminoguanidine attenuates renal dysfunction and injury in aging rats.

We have previously shown that aging is associated with increased lipid peroxidation, reductions in renal function, and increased glomerular sclerosis. The mechanism(s) responsible for these age-related changes are not clear. The purpose of the present studies was to determine if there was an increase in inducible nitric oxide synthase (iNOS) with aging, and if so, whether inhibition of iNOS would prevent aging injury by preventing free radical-mediated lipid peroxidation. iNOS protein expression in the kidney increased by approximately 90% by 24 months. Inhibition of iNOS by aminoguanidine (0.1% in drinking water) for 9 months, beginning at 13 months of age, reduced blood pressure, improved glomerular filtration rate by 70%, and renal plasma flow by 40%, whereas glomerular sclerosis was considerably reduced. Renal F2-isoprostanes and malondialdehyde levels, markers of oxidative stress and lipid peroxidation, were not reduced by aminoguanidine. Aminoguanidine also did not attenuate immunostaining for advanced glycosylation end products (AGE) in the kidneys. These findings suggest that aminoguanidine attenuates aging renal dysfunction by inhibiting a pathophysiologic function of iNOS that is independent of free radical-mediated lipid peroxidation or significant effects on AGE deposition.

Aging↗
PubMed1999

The Banff 97 working classification of renal allograft pathology.

BACKGROUND: Standardization of renal allograft biopsy interpretation is necessary to guide therapy and to establish an objective end point for clinical trials. This manuscript describes a classification, Banff 97, developed by investigators using the Banff Schema and the Collaborative Clinical Trials in Transplantation (CCTT) modification for diagnosis of renal allograft pathology. METHODS: Banff 97 grew from an international consensus discussion begun at Banff and continued via the Internet. This schema developed from (a) analysis of data using the Banff classification, (b) publication of and experience with the CCTT modification, (c) international conferences, and (d) data from recent studies on impact of vasculitis on transplant outcome. RESULTS: Semiquantitative lesion scoring continues to focus on tubulitis and arteritis but includes a minimum threshold for interstitial inflammation. Banff 97 defines "types" of acute/active rejection. Type I is tubulointerstitial rejection without arteritis. Type II is vascular rejection with intimal arteritis, and type III is severe rejection with transmural arterial changes. Biopsies with only mild inflammation are graded as "borderline/suspicious for rejection." Chronic/sclerosing allograft changes are graded based on severity of tubular atrophy and interstitial fibrosis. Antibody-mediated rejection, hyperacute or accelerated acute in presentation, is also categorized, as are other significant allograft findings. CONCLUSIONS: The Banff 97 working classification refines earlier schemas and represents input from two classifications most widely used in clinical rejection trials and in clinical practice worldwide. Major changes include the following: rejection with vasculitis is separated from tubulointerstitial rejection; severe rejection requires transmural changes in arteries; "borderline" rejection can only be interpreted in a clinical context; antibody-mediated rejection is further defined, and lesion scoring focuses on most severely involved structures. Criteria for specimen adequacy have also been modified. Banff 97 represents a significant refinement of allograft assessment, developed via international consensus discussions.

Acute Disease↗
PubMed1998

HIV-1 kills renal tubular epithelial cells in vitro by triggering an apoptotic pathway involving caspase activation and Fas upregulation.

HIV-infected patients suffer several renal syndromes, which can progress rapidly from renal insufficiency to end-stage renal disease. Histologically, HIV-induced nephropathy is characterized by prominent tubulopathy with apoptosis of tubular cells. Clinical and experimental evidence suggests that renal injury may be directly related to virus infection. Although HIV-1 is a polytropic and not solely lymphotropic pathogen, the susceptibility of renal cells to HIV-1 remains to be determined. This paper demonstrates in vitro the permissiveness of proximal tubular epithelial cells (PTEC) to HIV-1 and describes the effects of PTEC infection to explain the pathogenesis of tubular damage in vivo. The results indicate that PTEC express HIV-specific receptor and coreceptors and sustain virus replication. We observed that HIV-1 infection causes the death of tubular cells by triggering an apoptotic pathway involving caspase activation. Fas upregulation but not Fas ligand expression was found in the infected PTEC. However, after HIV-1 infection, tubular cells became susceptible to apoptosis induced through Fas stimulation. Caspase inhibition prevented the death of the infected PTEC in spite of persistent viral replication. These findings may explain the prominent histopathology of HIV-associated nephropathy and demonstrate that the apoptosis of nonlymphoid cells can be directly induced by HIV-1.

Apoptosis↗
PubMed1998

Cell lines from kidney proximal tubules of a patient with Lowe syndrome lack OCRL inositol polyphosphate 5-phosphatase and accumulate phosphatidylinositol 4,5-bisphosphate.

The protein product of the gene that when mutated is responsible for Lowe syndrome, or oculocerebrorenal syndrome (OCRL), is an inositol polyphosphate 5-phosphatase. It has a marked preference for phosphatidylinositol 4,5-bisphosphate although it hydrolyzes all four of the known inositol polyphosphate 5-phosphatase substrates: inositol 1,4,5-trisphosphate, inositol 1,3,4,5-tetrakisphosphate, phosphatidylinositol 4,5-bisphosphate, and phosphatidylinositol 3,4,5-trisphosphate. The enzyme activity of this protein is determined by a region of 672 out of a total of 970 amino acids that is homologous to inositol polyphosphate 5-phosphatase II. Cell lines from kidney proximal tubules of a patient with Lowe syndrome and a normal individual were used to study the function of OCRL. The cells from the Lowe syndrome patient lack OCRL protein. OCRL is the major phosphatidylinositol 4,5-bisphosphate 5-phosphatase in these cells. As a result, these cells accumulate phosphatidylinositol 4,5-bisphosphate even though at least four other inositol polyphosphate 5-phosphatase isozymes are present in these cells. OCRL is associated with lysosomal membranes in control proximal tubule cell lines suggesting that OCRL may function in lysosomal membrane trafficking by regulating the specific pool of phosphatidylinositol 4,5-bisphosphate that is associated with lysosomes.

Binding Sites↗
PubMed1998

Renal disease in Down syndrome: autopsy study with emphasis on glomerular lesions.

A range of renal diseases have been previously described in patients with Down syndrome. With increased survival, it appears that a growing number of these patients present with chronic renal failure. Definition of underlying causes of renal failure could potentially lead to prevention of progressive renal dysfunction in this population. We report two index cases of teenaged Down patients who presented with proteinuria and focal segmental glomerulosclerosis with hyalinosis, not previously described in this population. In addition, autopsy files were reviewed at the Johns Hopkins Hospital to assess renal and especially glomerular pathology in Down patients. Additional cases, including acute glomerulonephritis with early crescents and vasculitis, minimal change disease, and membranous nephropathy, were identified; the latter two diseases had not been previously reported in patients with Down syndrome. Semiquantitative studies on glomerular changes in all cases examined through autopsy also were performed. The only pathological finding that was significantly more common in the Down syndrome group, compared with age-matched cases from the autopsy files, was cystic dilation of Bowman's space. Histological findings described as increased in the Down population in previously published autopsy studies were also present in the control population, highlighting the need to adequately control such studies. The cases of acquired glomerular disease reported here were seen largely after the first decade of life. Monitoring of Down patients for renal and especially glomerular disease should be done regularly as patients age into the second and third decades.

Adolescent↗
PubMed1998

Heterogeneity of glomerular size in normal donor kidneys: impact of race.

Glomerular size has been the subject of many studies and, in a number of settings, has a direct association with the development of glomerular sclerosis. However, the normal distribution of glomerular size has not been thoroughly evaluated in the general population in the United States. To address this issue, we analyzed the baseline biopsy specimens of 103 human donor kidneys to determine the maximal planar area (MPA) of the glomerular tuft in a heterogeneous human population. The MPA of each glomerulus was determined by measurement of sections through the vascular pole and/or origin of the proximal tubule, and was determined on each section by two methods: point counting and computer planimetry. There was very high agreement between these two methods. Multivariate analysis was used to identify significant correlates with MPA. Overall, younger donors had smaller glomeruli (P < 0.0001). Black donors had a larger MPA (23.4+/-8.6 mm2 x 10(-3)) than white donors (17.9+/-6.7 mm2 x 10(-3); P < 0.001), independent of donor age. MPA was not significantly different between genders. This heterogeneity in glomerular size may confound clinical studies if not recognized and may help explain differences in glomerular structure and function in response to injurious processes.

Adult↗
PubMed1998

Digital imaging of black and white photomicrographs: impact of file size.

The publication of black and white photomicrographs has a long tradition in pathology. High-resolution film and quality objectives have been the backbone of generating quality photomicrographs suitable for publication. However, the digital imaging revolution has changed the way we view and capture images. As the quality of image capture devices increases and as their price decreases, more and more investigators are using digital imaging, and the use of color digital imaging for teleconferencing, telediagnosis, and reproduction is now well established. The purpose of this study was to determine the file sizes needed to obtain publication-quality black and white images using digital imaging technology. In this study, four experts in renal pathology reviewed 70 black and white images of various file sizes obtained from specimens representing a variety of renal histopathology. Without knowledge of the file size, the four renal pathologists graded the degree of pixelation, and the overall diagnostic and publication quality of the images. In all cases, digital imaging was capable of obtaining publication quality images equal to those achieved using film. The file size needed to achieve publication quality black and white images depended on magnification, with lower magnification images requiring larger file sizes.

Computer Communication Networks↗
PubMed1998

Vitamin E ameliorates enhanced renal lipid peroxidation and accumulation of F2-isoprostanes in aging kidneys.

Aging results in progressive glomerular sclerosis and reductions in glomerular filtration rate (GFR). Oxidative stress may be an important mechanism for the aging process, but to date the role of oxidative stress on renal aging has not been determined. The present study was performed to determine whether age-related alterations in renal hemodynamics and morphology were associated with oxidative stress and whether this could be attenuated by chronic administration of vitamin E. Rats, aged 13 mo, were given either control diet containing vitamin E 50 IU/kg (n = 6) or a high-vitamin E diet (5,000 IU/kg; n = 6) for 9 mo. Another group of rats (3-4 mo old; n = 7) served as young controls. Aging was accompanied by a 60% reduction in GFR, a threefold increase in renal F2 isoprostanes, newly discovered vasoconstrictive F2-like prostaglandins generated by free radical-mediated lipid peroxidation. Renal aging was also associated with an increase in oxidant-sensitive heme oxygenase, advanced glycosylation end products (AGEs), and the AGE receptor, RAGE. AGE-RAGE interaction has been shown to induce oxidative stress. With high-vitamin E diet, GFR was increased by 50%, F2 isoprostanes were suppressed, and expression of heme oxygenase and RAGE was attenuated. There was also a tendency for glomerular sclerosis to be attenuated. These data demonstrate that age-related decline in renal function is accompanied by oxidative stress and that administration of antioxidants, such as vitamin E, could attenuate the decline in renal function.

Aging↗
PubMed1997

Evaluation of pancreas transplant needle biopsy: reproducibility and revision of histologic grading system.

BACKGROUND: Tissue samples for the diagnosis of pancreatic allograft rejection are now obtained routinely through the application of the percutaneous needle biopsy technique. The availability of biopsy material (89% adequate for diagnosis in our setting) presents a challenge for pathologists who are asked to provide a fast and accurate diagnosis of rejection and its severity, while at the same time being able to differentiate rejection from other causes of graft dysfunction. METHODS: To differentiate rejection from other pathologic processes, 26 histologic features were assessed in 92 biopsies performed for confirmation of clinical diagnosis of rejection and the results were compared with 31 protocol biopsies, 12 allograft pancreatectomies with non-rejection pathology, and 30 native pancreas resections with various disease processes. RESULTS: Based on these comparisons, a constellation of findings relating to the vascular, septal, and acinar inflammation was identified for the diagnosis of rejection. Application of these features led us to revise our scheme for grading rejection (ranging from 0-normal to V-severe rejection) to include the categories of "inflammation of undetermined significance" and "minimal rejection." The scheme was used by five pathologist to grade 20 biopsies independently of any clinical data and the interobserver level of agreement was highly significant (kappa=0.83, P<0.0001). This grading scheme was applied blindly to all (183) biopsies from 77 patients with 6-52 months of follow-up. The correlation of the highest degree of rejection on each patient and ultimate graft loss (0% for grades 0-I, 11.5% for grade II, 17.3% for grade III, 37.5% for grade IV, and 100% for grade V) was highly statistically significant (P<0.002). The fraction of grafts lost due to pure immunologic causes increased proportionally to the grade of rejection (0, 50, 66, and 100% for grades II, III, IV, and V, respectively). CONCLUSIONS: This study provides strong support for the proposed pancreas rejection grading scheme and confirms its potential for practical use.

Adult↗
PubMed1997

Cell lines with extended in vitro growth potential from human renal proximal tubule: characterization, response to inducers, and comparison with established cell lines.

Few model systems exist for the study of injury to human renal proximal tubule epithelium. Optimized differentiated human renal epithelial cell lines with extended in vitro growth potential would provide an alternative model system to primary culture or other available non-human mammalian kidney cell lines. For this purpose, human renal tubule epithelial cells were isolated from normal kidney cortex and exposed in culture to a hybrid immortalizing virus, adenovirus 12-SV40. Cell lines were developed by limiting dilution, and three selected cell lines were screened for growth pattern, production of immortalizing virus, tumorigenicity, and ploidy. Cell lines were also monitored for response to inducer agents and matrix factors and were screened for expression of biochemical properties and differentiation markers of renal epithelium. All three are nonproducers of the immortalizing virus and are nontumorigenic. They grow in monolayer, have intermediate growth kinetics, and express markers of renal proximal tubular epithelium by immunohistochemistry. They also express biochemical properties comparable to other widely used proximal tubular cell lines including LLC-RK1, OK, and HK-2 and comparable to human tubular cells in stable culture. Growth medium containing low levels of fetal calf serum, or epidermal growth factor combined with parathyroid hormone, produced optimal growth characteristics, brush border enzyme expression, biochemical properties, and glucose transport in a selected cell line. The addition of dimethyl sulfoxide allows maintenance in morphologically intact monolayers for prolonged periods. These cell lines should be useful model systems for the study of human renal proximal tubular injury or disease.

Adenosine Triphosphate↗
PubMed1997

Adhesion molecules and rejection of renal allografts.

Despite an increasing amount of immunohistochemical and molecular biology data relating to the pathogenesis of kidney transplant rejection, the pathological diagnosis of this condition still rests on routine light microscopy. The detection of changes in expression and distribution of adhesion molecules in renal allograft biopsies may open a new era of increased accuracy of rejection diagnosis. Of the various adhesion molecule reactivities, peritubular capillary VCAM-1 staining appears to be the most specific finding for chronic rejection. This same staining reaction is seen in acute rejection, but may have less specificity in that setting.

Animals↗
PubMed1997

Long-term dietary supplementation with L-arginine prevents age-related reduction in renal function.

Aging is associated with loss of nephron function and reductions in serum L-arginine and excretion of nitric oxide (NO) metabolites. The present study was performed to determine if long-term dietary treatment with L-arginine, the NO synthase substrate, could prevent age-related renal injury. Studies were performed in four groups of rats, aged 12-13 mo, for 8 mo: group 1 received L-arginine (2% in 2.5% corn syrup, n = 5); group 2 received sodium nitrite, an NO donor (0.1%, in 2.5% syrup, n = 7); group 3 was an untreated control group (n = 7); group 4 was treated with 2.5% corn syrup (n = 5). Urinary protein increased and urinary nitrate/nitrite decreased with age in controls, but, during L-arginine treatment, urinary protein decreased and nitrate/nitrite increased. Two weeks after L-arginine was stopped, urinary protein had increased and nitrate/nitrite had decreased to the same level as in controls. L-Arginine treatment increased glomerular filtration rate (GFR) by 50% compared with untreated controls. In contrast, nitrite had no effect on GFR. Morphologically, L-arginine protected against aging injury by reducing the number of sclerotic glomeruli. In summary, we found that L-arginine prevented the age-related glomerular injury and reduction in GFR. The mechanism of protection, however, may be independent of NO.

Aging↗