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Kerstin Amann

Publications and source records attributed to Kerstin Amann.

At least 37 records · Page 2Linked to original sources
PubMed2006

Transient encephalopathy complicating poststreptococcal glomerulonephritis in an adult with diagnostic findings consistent with cerebral vasculitis.

We report the case of a young woman who had transient encephalopathy with nausea, cognitive impairment, 2 generalized seizures accompanied by visual impairment, and stenotic alterations of cerebral vessels lasting for weeks until complete resolution. These findings were associated with an elevated antideoxyribonuclease B level and biopsy-proven poststreptococcal glomerulonephritis. At the time of the encephalopathy, the patient had no electrolyte level disturbances, an only mildly elevated urea level, and moderate arterial hypertension and was on methylprednisolone therapy. For a couple of days, cranial magnetic resonance imaging showed multiple disseminated asymmetric hyperintensities on T(2)-weighted and fluid-attenuated inversion recovery, suggesting vasogenic edema. However, Doppler ultrasound examinations showed stenoses of extracerebral and multiple intracerebral arteries that persisted for several weeks, lasting considerably longer than the cerebral edema. This finding does not fit the context of hypertensive or steroid-induced encephalopathy, but is consistent with diagnosis of an accompanying vasculitis. Treatment with methylprednisolone for several weeks was associated with resolution of arterial stenoses and neurological symptoms, complete reversibility of Doppler sonographic findings, and significant improvement in renal function.

Adult↗
PubMed2005

Damage to the peritoneal membrane by glucose degradation products is mediated by the receptor for advanced glycation end-products.

Peritoneal dialysis is limited by morphologic changes of the peritoneal membrane. Use of peritoneal dialysis fluids (PDF) that contain glucose degradation products (GDP) generates advanced glycation end-products (AGE) within the peritoneal cavity. It is unknown whether peritoneal damage is causally related to AGE-receptor for AGE (RAGE) interaction. The effects of PDF were compared with different amounts of GDP on morphologic changes of the peritoneal membrane in 48 wild-type (WT) and 48 RAGE-deficient mice. PDF (1 ml) were instilled twice daily over a period of 12 wk. Groups with eight animals each received no manipulation (sham); sham instillation (sham i.p.); or filter-sterilized, glucose-free, conventional low GDP- or high GDP PDF. In vitro (generation of AGE fluorescence in PDF) and in vivo (immunohistochemistry for carboxymethyllysine), a GDP-dependent increase of AGE formation occurred. Inflammation and neoangiogenesis were augmented in WT mice that were treated with high GDP accompanied by upregulation of CD3+ T cells, increased NF-kappaB binding activity, increased lectin, and vascular endothelial growth factor expression. Furthermore, pronounced submesothelial fibrosis was found with increased expression of TGF-beta1. Exposure to low GDP resulted in only mild inflammation and neoangiogenesis (compared with sham i.p.) and no fibrosis in WT mice. The findings in WT contrasted with those in RAGE-deficient mice, which showed no increased inflammation (CD3+ T cells and NF-kappaB binding activity), neoangiogenesis (by lectin and vascular endothelial growth factor expression), or fibrosis (expression of TGF-beta1) after long-term exposure to GDP-containing PDF. Peritoneal damage by GDP in PDF is dependent at least in part on AGE-RAGE interaction.

Animals↗
PubMed2005

Atrial distribution of connexin 40 and 43 in patients with intermittent, persistent, and postoperative atrial fibrillation.

BACKGROUND: Sustained atrial fibrillation (AF) causes alterations in atrial electrical and structural properties. Conflicting data regarding the structural remodeling of the gap junction proteins connexin (Cx) 40 and 43 in human and animal studies exists. We investigated the amount and distribution of Cx40 and Cx43 in three subtypes of AF. METHODS: In 50 patients undergoing coronary artery bypass graft and/or mitral or aortic valve surgery, right atrial appendages were taken and examined with immunoconfocal microscopy. Retrospectively, four groups were built: (1) sinus rhythm pre- and postoperative (SR, n=20), (2) intermittent AF, but SR prior to surgery (intAF, n=6), (3) postoperative AF (popAF, n=12), and (4) persistent AF, at least 3 month prior to surgery (persAF, n=12). We analyzed the amount of Cx40 and Cx43 and the degree of fibrosis in three randomly selected areas of each sample. RESULTS: As compared with SR, the amount of Cx40 was significantly reduced by 53% in persAF. The distribution pattern of Cx40 was heterogeneous in patients with SR, intAF, and popAF, whereas patients with persAF showed similar densities of Cx40 in the three examined areas. We found no significant difference in the amount of Cx43 between the four groups. The distribution pattern of Cx43 was heterogeneous in all four groups. The Cx40/Cx43 ratio was significantly reduced in patients with popAF and persAF by 51% and 53%, respectively. No difference was seen in the degree of fibrosis between the four groups. CONCLUSIONS: In this study, sustained AF leads to a reduction in the amount of Cx40. Together with a specific Cx40/Cx43 ratio, this may contribute to localized conduction abnormalities, facilitating the self-perpetuation of re-entry pathways in AF. In the time course of structural atrial remodeling these changes seem to be earlier than a concomitantly developing fibrosis.

Aged↗
PubMed2005

Native C-reactive protein increases whereas modified C-reactive protein reduces atherosclerosis in apolipoprotein E-knockout mice.

BACKGROUND: C-reactive protein (CRP) may have proatherogenic but also vasoprotective properties. We tested the hypothesis that the configuration of CRP (pentameric, or native [nCRP], versus monomeric, or modified [mCRP]) determines these different characteristics in an in vivo model. METHODS AND RESULTS: We investigated the effects of human nCRP and mCRP on the development of atherosclerosis in apolipoprotein E-knockout (ApoE(-/-)) mice. Treatment with nCRP for 8 weeks (2.5 mg/kg SC weekly) resulted in a 4-fold-higher mean aortic plaque area in 14-week-old female ApoE(-/-) mice compared with the saline controls. In contrast, mean plaque size was decreased by approximately 50% in mCRP-treated ApoE(-/-) mice (2.5 mg/kg SC weekly). Using immunohistochemistry, we report the natural presence of the mCRP antigen in saline controls. mCRP antigen was expressed in smooth muscle cells and extracellularly in the vicinity of the plaques to a similar level in both CRP-treated groups and saline controls. mCRP and ApoB colocalized with macrophages and were equally upregulated in all aortic plaques. Vascular cell adhesion molecule expression was increased, and CD154 and intercellular adhesion molecule showed a trend for higher expression in nCRP-treated compared with mCRP-treated mice. CD154 expression in the vessel wall and plaque size correlated significantly. mCRP-treated ApoE(-/-) exhibited higher serum levels of the antiinflammatory interleukin-10 compared with the other 2 groups. CONCLUSIONS: Here, we show that mCRP and nCRP have opposite effects on atherosclerosis in ApoE(-/-) mice. These data may explain in part the conflicting activities previously reported for CRP in models of atherogenesis.

Animals↗
PubMed2005

Stimulation of GCMa and syncytin via cAMP mediated PKA signaling in human trophoblastic cells under normoxic and hypoxic conditions.

Glial cells missing a (GCMa) belongs to a new transcription factor family. Syncytin was shown to be a target gene of GCMa. Here, we demonstrate that the protein kinase A (PKA) pathway acts upstream of GCMa. After transient transfection of BeWo cells with PKA, GCMa transcriptional activity and both GCMa and syncytin transcripts were upregulated. This increase was accompanied by further cellular differentiation. Using normoxic or hypoxic conditions to mimic pathophysiological settings known to diminish trophoblast differentiation, we found that gene repressive effects of oxygen deficiency were compensated by the induction of the PKA pathway. We propose that GCMa-driven syncytin expression is the key mechanism for syncytiotrophoblast formation.

Apoptosis↗
PubMed2005

Arterialisation of the portal vein as a model for the induction of hepatic fibrosis: description of microsurgical models in the rat.

Within the framework of liver transplantation, arterialisation of the portal vein in the case of non-recanalisable thrombosis has been reactivated. However, one of the consequences of this vascular reconstruction is the development of hepatic fibrosis. Clinical experience has shown that the development of fibrosis can be avoided by reducing portal inflow. We present, as a model for the induction of hepatic fibrosis, techniques of PVA, including transplantation. For PVA, several different techniques were used: the first with reduction of the portal inflow over a stent inserted in the right renal artery (PVA-B), the second with unrestricted flow using an aortic-portal segment (PVA-APS). The third technique was orthotopic liver transplantation with unrestricted portal arterialisation (OLTx-APS). Portal blood flow was measured with an ultrasonic flow probe. To determine the degree of hepatic fibrosis the amount of hydroxyproline was measured. Quantification of relative transcript levels of procollagen I was effected with real-time PCR using the TaqMan technology on a lightcycler instrument. The extracellular matrix was visualised with picro-sirius staining. Measurements with the ultrasonic probe showed a significant increase in flow rates, both with reduced (PVA-B) and unrestricted inflow (PVA-APS; OLTx-APS). The lowest survival rate (58%) was found in the group with unrestricted portal inflow. The reason for this was a high rate of thrombosis in the in the portal vascular tree (4 out of 12). In the OLTx-APS group four animals died within the first 3 postoperative days (69%), as a result of protracted postoperative shock. The overall survival rate was the highest (85%) in the group undergoing PVA with reduction of the portal inflow. PVA with unrestricted inflow was followed by a significant increase in extracellular collagen, which showed a clear correlation with the increase in the amount of hydroxyproline, the level of the mRNA for procollagen I and picro-sirius staining. With the operative PVA techniques presented herein, different arterial flow rates in the portal vein can be investigated. In our opinion these techniques represent an excellent animal model for studying the genesis of fibrosis and antifibrotic substances. By regulating the blood flow in the arterialised portal vein hepatic fibrosis can be reduced or even avoided. After a brief period of learning the microsurgical techniques, the surgeon can limit clamping times and achieve good results with these techniques.

Animals↗
PubMed2005

Expression of bone morphogenic protein 2/4, transforming growth factor-beta1, and bone matrix protein expression in healing area between vascular tibia grafts and irradiated bone-experimental model of osteonecrosis.

PURPOSE: For the surgical treatment of osteoradionecrosis after multimodal therapy of head-and-neck cancers, free vascular bone grafts are used to reconstruct osseous structures in the previously irradiated graft bed. Reduced, or even absent osseous healing in the transition area between the vascular graft and the irradiated graft bed represents a clinical problem. Inflammatory changes and fibrosis lead to delayed healing, triggered by bone morphogentic protein 2/4 (BMP2/4) and transforming growth factor (TGF)-beta(1). Given the well-known fibrosis-inducing activity of TGF-beta(1), an osteoinductive effect has been reported for BMP2/4. However, the influence of irradiation (RT) on this cytokine expression remains elusive. Therefore, the aim of the present in vivo study was to analyze the expression of BMP2/4, TGF-beta(1), collagen I, and osteocalcin in the transition area between the bone graft and the graft bed after RT. METHODS AND MATERIALS: Twenty Wistar rats (male, weight 300-500 g) were used in this study. A free vascular tibia graft was removed in all rats and maintained pedicled in the groin region. Ten rats underwent RT with 5 x 10 Gy to the right tibia, the remainder served as controls. After 4 weeks, the previously removed tibia grafts were regrafted into the irradiated (Group 1) and nonirradiated (Group 2) graft beds. The interval between RT and grafting was 4 weeks. After a 4-week osseous healing period, the bone grafts were removed, and the transition area between the nonirradiated graft and the irradiated osseous graft bed was examined histomorphometrically (National Institutes of Health imaging program) and immunohistochemically (avidin-biotin-peroxidase complex) for the expression of BMP2/4, TGF-beta(1), collagen I, and osteocalcin. RESULTS: Absent or incomplete osseous healing of the graft was found in 9 of 10 rats after RT with 50 Gy and in 1 of 10 of the rats with nonirradiated osseous grafts. Histomorphometrically, the proportion of osseous healing in the transition area was 17% in Group 1 and 48% in Group 2 (p = 0.001). Compared with the nonirradiated rats, reduced enchondral and perichondral ossification was found in the healing area after RT, with a reduction of BMP2/4 and osteocalcin expression. TGF-beta(1) and collagen I expression in the transition area to the irradiated osseous graft bed was significantly increased compared with that in the nonirradiated osseous graft bed. CONCLUSION: After RT, osseous healing of vascular bone grafts is significantly reduced and may be a result of radiation-induced inhibition of BMP2/4 and osteocalcin expression. In addition, induction of TGF-beta(1) and collagen I expression occurs. Because the effects of the TGF-beta superfamily are manifold and partially unknown, additional research directions could be in the exogenous application of BMP2/4 and inhibition of TGF-beta(1) by antibody treatment to search for appropriate therapeutic approaches for improving osseous healing in the irradiated graft bed.

Animals↗
PubMed2005

Restricted-expressed proliferation-associated protein (Repp86) expression in squamous cell carcinoma of the oral cavity.

PURPOSE: To determine the expression of repp86 (restricted-expressed protein of 86 kDa theoretical molecular mass), a proliferation- associated protein expressed in S-, G(2)- and M-phases of the cell cycle, in samples of normal mucosa as well as squamous cell carcinoma of the oral cavity (OSCC). PATIENTS AND METHODS: The repp86 labeling index (LI) was determined imunohistochemically in ten samples of normal oral mucosa and 59 samples of OSCC. Repp86 LI was correlated with tumor stage, histopathologic grading, and the expression of Ki-67 and topoisomerase IIalpha. RESULTS: Repp86 was detectable in all tissues analyzed. The mean LI was 4.7% for normal mucosa and 18.4% for squamous cell carcinoma (p < 0.0001). Repp86 expression was not related to tumor size, lymph node invasion, or histopathologic grading but was positively correlated with Ki-67 index (r = 0.48; p < 0.01) as well as with topoisomerase IIalpha (r = 0.39; p < 0.01). Ki-67 and topoisomerase IIalpha levels were also significantly correlated with each other (r = 0.34; p < 0.05). CONCLUSION: These results indicate that repp86 expression can be an additional proliferation marker among Ki-67 and topoisomerase IIalpha in OSCC. Further research will be directed at the evaluation of the prognostic value of repp86 expression in OSCC as well as in leukoplakia and early-stage OSCC.

Adult↗
PubMed2005

Untreated 'blow-in' fracture of the orbital floor causing a mucocele: report of an unusual late complication.

BACKGROUND: Several severe complications have been described with blow-in fractures. Therefore, immediate surgical treatment of these fractures has been recommended. To date, there is only minimal knowledge on long-term complications of blow-in fractures that have remained untreated. The present case report describes a late complication of an untreated blow-in fracture of the orbital floor. CASE: A 37-year-old male was involved in a car accident 16 years before. At that time, a non-dislocated midfacial fracture was diagnosed and remained untreated because of the lack of clinical symptoms. Four months before surgery an exophthalmos of the left globe began to develop. CT examination revealed a consolidated blow-in fracture of the left orbital floor and an opaque mass around the dislocated bony fragments. By an infraorbital approach the bony fragments and the surrounding mass were removed. Histological examination of the removed material revealed a cystic structure lined with respiratory epithelium. Therefore, the diagnosis 'post-traumatic mucocele in the orbit caused by dislocated respiratory epithelium from the maxillary sinus' was made. CONCLUSION: Even if blow-in fractures do not cause complications immediately after trauma, late complications like mucoceles can occur after several symptom-free years. Therefore, early reconstruction should be intended even in asymptomatic cases of blow-in fractures with minimal displacement of the bony fragments.

Accidents, Traffic↗
PubMed2005

Endothelin-1 and ETA/ETB receptor protein and mRNA: expression in normal and vascularized human corneas.

PURPOSE: Neovascularization of the cornea causes blindness and increases the risk of immune rejections after keratoplasty. The purpose of this study was to investigate involvement of the potent angiogenic growth factor endothelin (ET)-1 and its receptors, ETA and ETB, in corneal neovascularization. METHODS: ET-1, ETA, and ETB receptor protein expression was evaluated in nonvascularized and vascularized human corneas by immunohistochemistry. Epithelial ET-1 protein expression of both groups was compared using a semiquantitative scoring system. Double immunofluorescence was used to colocalize ETA and ETB receptor with CD31. In situ hybridization and immunoelectron microscopy analyzed ET-1 and its receptors in normal and vascularized corneas. RESULTS: Nonvascularized corneas displayed ET-1 and ETA/ETB receptor protein and mRNA in epithelial and some corneal endothelial cells. ETA more than ETB receptors were expressed on some keratocytes. In vascularized corneas, ET-1 and ETA/ETB receptor expression was found in the endothelial lining of new blood vessels (as shown by CD31-colocalization). ET-1 protein expression was significantly increased in the epithelium of vascularized corneas (P < 0.001). Immunogold localized ET-1 and its receptors to the nuclear/perinuclear space and to the luminal side of endothelial cells of new blood vessels. CONCLUSIONS: In corneal neovascularization, ET-1 protein and mRNA expression is upregulated in epithelial cells. Together with ET-1, ETA, and ETB receptor expression on endothelial cells of ingrown new blood vessels, this points to an involvement of ET-1 and its receptors in corneal angiogenesis. As potent ETA and ETB receptors are available, the endothelin system may represent an additional target for corneal antiangiogenic therapy.

Cornea↗
PubMed2005

Ewing sarcoma of the mandible in a child: interdisciplinary treatment concepts and surgical reconstruction.

Ewing's sarcoma is the second most common primary bone malignancy in childhood and adolescence. We present a standardized interdisciplinary treatment protocol according to the EURO-E.W.I.N.G. 99 study, applied in the treatment of a 7-year-old patient with localized Ewing's sarcoma of the left mandible. After six blocks of VIDE (vincristine/ifosfamide/doxorubicin/etoposide) chemotherapy and stem cells rescue, intensity modulated external radiation with 48.6 Gy and subsequent high dose therapy with busulphan-melphalan were administered. Tumor resection and immediate bony reconstruction was performed using a microvascular fibula graft 10 weeks after radiation. Because of the effective neoadjuvant treatment, no extensive soft tissue resection was necessary. Healing of the osteosynthesis was uneventful. No local or systemic recurrence and no signs of significant facial deformity were found after 12 month follow-up. The presented case underlines the requirement for multidisciplinary protocols involving radiologists, pathologists, oncologists, radiation oncologists, and surgeons for accurate diagnosis and appropriate therapy. To preserve cosmetics and function within the craniofacial area after tumor resection in children, microvascular reconstructive procedures can be successfully performed with a vascularized fibular graft.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Effects of estrogens on cardiovascular structure in uninephrectomized SHRsp rats.

BACKGROUND: The risk of cardiovascular disease in uremic patients is greater in male than in female patients. Estrogens seem to play a cardioprotective role until menopause. Experimental data on the effect of estrogens on cardiovascular damage are controversial and potential underlying mechanisms especially in renal failure have not been fully clarified. METHODS: Three-month-old female uninephrectomized stroke-prone spontaneously hypertensive (SHRsp) rats were sham-operated or ovariectomized. Subsequently, they received either vehicle (sesame oil) or 17-beta-3 benzoate estradiol (E2) (25 microg/day) or estriol (E3) (0.02 mg/day), respectively. After 3 months the animals were sacrified and the organs were harvested using pressure-controlled perfusion fixation. Stereologic parameters such as capillary length density (L(V)), mean intercapillary distance (MID), and volume density of the interstitial tissue (Vv) were quantitated. Additionally, expression of transforming growth factor-beta (TGF-beta), vascular endothelial growth factor (VEGF), flt-1, endothelial nitric oxide synthase (eNOS), endothelin-1 (ET-1), endothelin A receptor (ETA) receptor, and alpha estrogen receptor was assessed using immunohistochemistry. Intramyocardial capillaries and the aorta were investigated by morphometric methods. RESULTS: L(V) (mm/mm(3)) was significantly lower (2421 +/- 500) and MID (microm) significantly higher (22.2 +/- 2.33) in vehicle-treated uninephrectomized/ovariectomized compared to uninephrectomized/sham-ovariectomized controls (L(V) 3629 +/- 960, MID 12.7 +/- 2.7) as well as estradiol (L(V) 3340 +/- 739, MID 12.1 +/- 4.96) and estriol (L(V) 4655 +/- 618, MID 14.2 +/- 2.89) treated uninephrectomized/ovariectomized animals. The volume density of the cardiac interstitium was higher in vehicle-treated uninephrectomized/ovariectomized animals compared to uninephrectomized/sham-ovariectomized, estradiol and estriol treated uninephrectomized/ovariectomized rats. The protein level expression of TGF-beta was higher in vehicle treated uninephrectomized/ovariectomized compared to uninephrectomized/sham and all treatment groups. CONCLUSION: In ovariectomized SHRsp rats with moderate renal failure cardiac lesions were strikingly less after estradiol or estriol treatment. The results document a beneficial role of estrogens on cardiac abnormalities in a model of moderate renal dysfunction.

Animals↗
PubMed2005

Adrenomedullin reduces mesangial cell number and glomerular inflammation in experimental mesangioproliferative glomerulonephritis.

BACKGROUND: Adrenomedullin (ADM) is a vasodilator peptide that is abundantly expressed in the kidney. ADM has antiproliferative effects on glomerular mesangial cells (MC) in vitro. Whether or not treatment with ADM can reduce MC proliferation in vivo [i.e., in mesangioproliferative glomerulonephritis (GN)] is unknown. We tested the hypothesis that ADM substitution reduces MC proliferation in GN. METHODS: GN in rats was induced by injection of an anti-Thy-1.1 antibody. Rats received osmotic minipumps, which continuously delivered rat ADM (500 ng/hour, N = 11), or vehicle (N = 13) from day 3 to day 6 after GN induction. Rats were sacrificed 6 days after induction of GN. On kidney sections, cells staining positive for proliferating cell nuclear antigen, mesangial cells, monocytes, and apoptotic cells were counted. Parameters of inflammation and fibrosis were measured in renal cortex and sieved glomeruli by real-time polymerase chain reaction (PCR). RESULTS: Systolic blood pressure, diuresis, albuminuria, creatinine clearance, microaneurysm formation, and mesangial matrix expansion were not influenced by ADM infusion. However, ADM treatment significantly reduced the number of MC, showed a tendency to reduce total glomerular cell proliferation, and significantly increased apoptosis. ADM-treated GN animals showed significantly less glomerular monocyte infiltration. ADM treatment normalized transforming growth factor (TGF)-beta1 mRNA expression and reduced monocyte chemoattractant protein-1 (MCP-1), osteopontin, plasminogen activator inhibitor-1 (PAI-1), collagen I, and collagen III mRNA expression significantly. CONCLUSION: Exogenous ADM infusion reduces MC number and glomerular monocyte infiltration in the state of mesangial proliferation during acute experimental mesangioproliferative GN. These findings indicate that ADM can influence the course of mesangioproliferative GN.

Adrenomedullin↗
PubMed2005

Racial differences in renal arteriolar structure in children with minimal change nephropathy.

BACKGROUND: African Americans are at increased risk for hypertension and chronic renal disease. Some data suggest this results from renal microvascular disease. The aim of this study was to determine if renal vascular changes were more pronounced in African Americans, were independent of blood pressure, and occurred in early childhood. METHODS: We performed morphometric analysis on small cortical arteries and arterioles from 44 renal biopsies done in African American and white children (mean age 8.4 +/- SD 5.0 years) with minimal change nephropathy. Outer and inner vessel diameters were measured and wall:lumen and wall:outer diameter ratios (WT/OD) calculated. Clinical data on blood pressure, steroid use, serum creatinine, gender, age, and proteinuria were abstracted by chart review. A z score for systolic and diastolic blood pressure was calculated. Follow-up clinical data were available for 11 children. Data were compared using analysis of covariance (ANCOVA) and t test for paired data. RESULTS: Lumen diameters of African Americans were 3.1 microm (23%) smaller that those of white children (P = 0.024). Similarly, their WT/OD was greater than in the whites, 0.31+/-0.03 vs. 0.28 +/- 0.02 (P= 0.048). These changes were independent of age, steroid use, systolic blood pressure and diastolic blood pressure z scores. Follow-up data showed a rise in serum creatinine (>50%) in five patients, +1.42 +/- 0.79 mg/dL (P = 0.016), of whom four were African American. There was no change in blood pressure. CONCLUSION: The renal arterioles of African American children with minimal change nephropathy exhibit significantly smaller lumens and thicker walls than white children. The changes occur very early in life and are independent of age, blood pressure, and steroid use. Such changes may contribute to the African American predisposition to chronic renal disease and hypertension.

Black or African American↗
PubMed2005

p27(Kip1) Knockout mice are protected from diabetic nephropathy: evidence for p27(Kip1) haplotype insufficiency.

BACKGROUND: High glucose up-regulates the mesangial cell expression of p27(Kip1), an inhibitor of cyclin-dependent kinases/cyclin complexes. Previous in vitro studies using cultured mesangial cells from p27(Kip1-/-) mice demonstrated that these cells do not undergo high glucose-mediated cellular hypertrophy. Since glomerular hypertrophy is an early feature of diabetic nephropathy and may precede the development of glomerulosclerosis, interference with p27(Kip1) expression may attenuate diabetic nephropathy. However, it is unclear whether deletion of p27(Kip1) protects the kidneys of diabetic nephropathy in vivo. METHODS: Type 1 diabetes mellitus was induced in p27(Kip1+/+), p27(Kip1+/-), and p27(Kip1-/-) mice by injection of streptozotocin (STZ). Mice were studied for 6 weeks. Animals injected with citrate buffer only served as controls. At the end of the experiments, urine was collected, albuminuria was determined with an enzyme-linked immunosorbent assay (ELISA), and blood glucose concentrations were measured. Kidneys were perfusion-fixed for quantitative morphologic analysis with glutaraldehyde and for immunohistochemical studies with formaldehyde. Glomerular cell number and volume were analyzed. Glomerulosclerosis, tubulointerstitial, and vascular damage indices were semiquantitatively assessed according to standard methodology. Quantitative glomerular parameters (cell numbers and volumes of endothelial, mesangial, and epithelial cells) were measured on semithin sections. Expression of transforming growth factor-beta1 (TGF-beta1), laminin, and collagen type IV were determined by immunohistochemical staining. RESULTS: In contrast to animals only injected with citrate buffer, mice that received STZ developed hyperglycemia. There was no significant difference in the degree of hyperglycemia among p27(Kip1+/+), p27(Kip1+/-), and p27(Kip1-/-) mice. Diabetic p27(Kip1+/+), but not control p27(Kip1+/+) animals, developed albuminuria. Albuminuria was significantly reduced in diabetic p27(Kip1+/-) and more profoundly in p27(Kip1-/-) animals. Diabetic p27(Kip1+/+) mice revealed a significant increase in mean glomerular volume at 6 weeks. The volumes of mesangial and endothelial cells and podocytes all increased, whereas cell numbers were reduced, consistent with cell hypertrophy. Glomerular, endothelial, mesangial and podocyte hypertrophy were reduced in diabetic p27(Kip1+/-) and p27(Kip1-/-) animals. Diabetic p27(Kip1) (+/+) animals had significantly increased glomerulosclerosis, tubulointerstium, and vascular damage indices compared to nondiabetic p27(Kip1+/+) controls. Diabetic p27(Kip1-/-) mice exhibited significantly less structural damage than diabetic wild-type animals. Diabetic p27(Kip1+/-) animals revealed intermediate glomerulosclerosis, tubulointerstium, and vascular damage values. Immunohistological stainings demonstrated increases in TGF-beta1, collagen type IV, and laminin expression in kidneys of diabetic p27(Kip1+/+) animals compared to nondiabetic p27(Kip1+/+) controls. Staining intensity for type IV collagen and laminin, but not for TGF-beta1, was significantly lower in diabetic p27(Kip1-/-) mice. CONCLUSION: Deletion of p27(Kip1) attenuates the functional and morphologic features of diabetic nephropathy. Although deletion of p27(Kip1) abolished some parameters of diabetic glomerular hypertrophy, the significant reduction of TGF-beta1 expression in the tubulointerstitium indicates that other protective mechanisms could be operative. The p27(Kip1) gene is haplo-insufficient because diabetic p27(Kip1)+/- mice exhibited an intermediate degree of functional and structural renal injury. Our data shows that p27(Kip1) plays an important role in diabetic nephropathy.

Albuminuria↗
PubMed2005

Nephron number and renal risk in hypertension and diabetes.

It has been proposed that "nephron underdosing," i.e., a low number of nephrons at the time of birth, is linked to essential hypertension and a greater propensity to develop progressive loss of renal function after renal injury. This hypothesis was confirmed recently by examining the number of glomeruli in patients with essential hypertension. The mechanisms through which a low number of nephrons causes hypertension have not been clarified, but it is likely that functional changes in postglomerular segments of the nephron, e.g., handling of sodium, play an important role. Neonatal uninephrectomy increases BP, renders BP salt sensitive, and renders the kidney more susceptible to damage. Apart from genetic factors, fetal/maternal malnutrition during pregnancy seems to play an important role in the pathogenesis of nephron underdosing. Furthermore, intrauterine programming during organogenesis, e.g., by hyperglycemia, seems to be important: In animal experiments, offspring of either hyperglycemic or diabetic mothers have fewer nephrons.

Animals↗
PubMed2004

Role of podocytes for reversal of glomerulosclerosis and proteinuria in the aging kidney after endothelin inhibition.

The cause of focal-segmental glomerulosclerosis as a consequence of physiological aging, which is believed to be inexorable, is unknown. This study investigated whether inhibition of endothelin-1, a growth-promoting peptide contributing to renal injury in hypertension and diabetes, affects established glomerulosclerosis and proteinuria in the aged kidney. We also determined the role of endothelin receptors for podocyte injury in vivo and in vitro. Aged Wistar rats, a model of spontaneous age-dependent glomerulosclerosis, were treated with the orally active endothelin subtype A (ET(A)) receptor antagonist darusentan, and evaluation of renal histology, renal function studies, and expression analyses were performed. In vitro experiments using puromycin aminonucleoside to induce podocyte injury investigated the role of ET(A) receptor signaling for apoptosis, cytoskeletal injury, and DNA synthesis. In aged Wistar rats, established glomerulosclerosis and proteinuria were reduced by >50% after 4 weeks of darusentan treatment, whereas blood pressure, glomerular filtration rate, or tubulo-interstitial renal injury remained unaffected. Improvement of structural injury in glomeruli and podocytes was accompanied by a reduction of the expression of matrix metalloproteinase-9 and p21Cip1/WAF1. In vitro experiments blocking ET(A) receptors using specific antagonists or RNA interference prevented apoptosis and structural damage to podocytes induced by puromycin aminonucleoside. In conclusion, these results support the hypothesis that endogenous endothelin contributes to glomerulosclerosis and proteinuria in the aging kidney. The results further suggest that age-dependent glomerulosclerosis is not merely a "degenerative" but a reversible process locally confined to the glomerulus involving recovery of podocytes from previous injury.

Aging↗