Hannu Jalanko

Nephrin strands contribute to a porous slit diaphragm scaffold as revealed by electron tomography

Nephrin is a key functional component of the slit diaphragm, the structurally unresolved molecular filter in renal glomerular capillaries. Abnormal nephrin or its absence results in severe proteinuria and loss of the slit diaphragm. The diaphragm is a thin extracellular membrane spanning the approximately 40-nm-wide filtration slit between podocyte foot processes covering the capillary surface. Using electron tomography, we show that the slit diaphragm comprises a network of winding molecular strands with pores the same size as or smaller than albumin molecules, as demonstrated in humans, rats, and mice. In the network, which is occasionally stratified, immunogold-nephrin antibodies labeled individually detectable globular cross strands, about 35 nm in length, lining the lateral elongated pores. The cross strands, emanating from both sides of the slit, contacted at the slit center but had free distal endings. Shorter strands associated with the cross strands were observed at their base. Immunolabeling of recombinant nephrin molecules on transfected cells and in vitrified solution corroborated the findings in kidney. Nephrin-deficient proteinuric patients with Finnish-type congenital nephrosis and nephrin-knockout mice had only narrow filtration slits that lacked the slit diaphragm network and the 35-nm-long strands but contained shorter molecular structures. The results suggest the direct involvement of nephrin molecules in constituting the macromolecule-retaining slit diaphragm and its pores.

Management of congenital nephrotic syndrome of the Finnish type

Congenital nephrotic syndrome of the Finnish type (CNF) is a rare autosomal recessively inherited disease characterised by intrauterine onset of massive urinary loss of proteins, 90% of which is albumin. The CNF gene has been localised to the long arm of chromosome 19, but the pathogenesis remains unclear. Historically, all CNF patients died, usually within the first 6 months of life. Today, a normal life can be achieved for a child with CNF by correcting the protein deficiency and normalising nutrition. This is accomplished by early intravenous albumin supplementation, nutritional support, aggressive treatment of complications and early renal transplantation, after bilateral nephrectomy and peritoneal dialysis. In the present article current treatment strategies are reviewed, and our own experience with 43 CNF patients during the last 10 years is presented.

Liposomal amphotericin B prevents invasive fungal infections in liver transplant recipients. A randomized, placebo-controlled study.

Eighty-six consecutive liver transplant recipients were prospectively randomized in a double-blind, placebo-controlled antifungal prophylaxis study. Seventy-seven patients received 5 days of prophylaxis starting during the transplantation with either liposomal amphotericin B (AmBisome) 1 mg/kg/day or placebo. Among 40 AmBisome-treated patients, no invasive Candida infection was seen during the first month, compared with 5 invasive Candida albicans infections among 37 control patients (P < 0.05). Furthermore, 1 placebo patient experienced Aspergillus niger pneumonia. Thus, the overall incidence of invasive fungal infections was 0/40 (0%) in the AmBisome group versus 6/37 (16%) in the placebo group (P < 0.01). Patient survival at 30 days was 92% versus 94% for AmBisome- and placebo-treated patients, respectively. One patient experienced backache related to AmBisome infusion. Two patients had transient thrombocytopenia possibly caused by AmBisome treatment. AmBisome was otherwise well tolerated. The total cost for all antifungal drugs used in both groups was equal. However, prophylaxis with AmBisome was

Congenital nephrotic syndrome

5000 less expensive than treatment of proven invasive fungal infections among placebo patients.

Role of nephrin in cell junction formation in human nephrogenesis.

Congenital nephrotic syndrome (CNS) is a rare kidney disorder characterized by heavy proteinuria, hypoproteinemia, and edema starting soon after birth. The majority of cases are caused by genetic defects in the components of the glomerular filtration barrier, especially nephrin and podocin. CNS may also be a part of a more generalized syndrome or caused by a perinatal infection. Immunosuppressive medication is not helpful in the genetic forms of CNS, and kidney transplantation is the only curative therapy. Before the operation, management of these infants largely depends on the magnitude of proteinuria. In severe cases, daily albumin infusions are required to prevent life-threatening edema. The therapy also includes hypercaloric diet, thyroxin and mineral substitution, prevention of thrombotic episodes, and prompt management of infectious complications. The outcome of CNS patients without major extrarenal manifestations is comparable with other patient groups after kidney transplantation.

Neurodevelopmental outcome in high-risk patients after renal transplantation in early childhood

Nephrin is a cell adhesion protein located at the slit diaphragm area of glomerular podocytes. Mutations in nephrin-coding gene (NPHS1) cause congenital nephrotic syndrome (NPHS1). We studied the developmental expression of nephrin, ZO-1 and P-cadherin in normal fetal kidneys and in NPHS1 kidneys. We used in situ hybridization and immunohistochemistry at light and electron microscopic levels. Nephrin and zonula occludens-1 (ZO-1) were first expressed in late S-shaped bodies. During capillary loop stage, nephrin and ZO-1 localized at the basal margin and in the cell-cell adhesion sites between developing podocytes, especially in junctions with ladder-like structures. In mature glomeruli, nephrin and ZO-1 concentrated at the slit diaphragm area. P-cadherin was first detected in ureteric buds, tubules, and vesicle stage glomeruli. Later, P-cadherin was seen at the basal margin of developing podocytes. Fetal NPHS1 kidneys with Fin-major/Fin-major genotype did not express nephrin, whereas the expression of ZO-1 and P-cadherin was comparable to that of control kidneys. Although early junctional complexes proved structurally normal, junctions with ladder-like structures and slit diaphragms were completely missing. The results indicate that nephrin is dispensable for early development of podocyte junctional complexes. However, nephrin appears to be essential for formation of junctions with ladder-like structures and slit diaphragms.

Recombinant human granulocyte-macrophage colony-stimulating factor in the treatment of febrile neutropenia: a double blind placebo-controlled study in children.

Abstract: Patient and graft survival rates of pediatric renal transplant recipients are currently excellent, but there are few reports regarding the long‐term neurodevelopmental outcome after renal transplantation (Tx) in early childhood. Children with renal failure from infancy would be expected to have a less favorable developmental prognosis. We report the neurodevelopmental outcome in 33 school‐age children transplanted between 1987 and 1995 when < 5 yr of age. We prospectively performed a neurological examination, magnetic resonance imaging (MRI) of the brain, electroencephalograms (EEGs), audiometry, and neuropsychological tests (NEPSY), and measured cognitive performance (WISC‐R); we related these results to school performance and to retrospective risk factors prior to Tx. Twenty‐six (79%) children attended normal school and 76% had normal motor performance. Six of the seven children attending a special school had brain infarcts on MRI. The EEG was abnormal in 11 (35%), and five (15%) received anti‐convulsive treatment after Tx. Sensorineural hearing loss was documented in six patients. The mean intelligence quotient (IQ) was 87, and 6–24% showed impairment in neuropsychological tests. The children attending a special school had been more premature, but had not had a greater number of pre‐ or neonatal complications. They had experienced a greater number of hypertensive crises (p = 0.002) and seizures (p = 0.03), mainly during dialysis, but the number of septic infections and the mean serum aluminum levels were not significantly greater than in the children with normal school performance. In these previously lethal diseases, the overall neurodevelopmental outcome is reassuring. However, it is of crucial importance to further minimize the risk factors prior to Tx.

Incidence and Predictors of Fractures in Children After Solid Organ Transplantation: A 5‐Year Prospective, Population‐Based Study

In a double blind study of 58 episodes of fever and profound neutropenia, children with cancer received either recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) or placebo, combined with identical antimicrobial therapy, i.e. imipenem, on admission. The criteria for discontinuation of therapy were identical. A difference was demonstrated both in the number of hospital days, totaling 252 days in the rhGM-CSF group and 354 in the placebo group, days receiving antibiotics (220 vs. 322), and in the resolution of neutropenia (4.5 days vs. 6.0 days; P < 0.05). The number of episodes requiring antimicrobial therapy for longer than 10 days was 5 of 28 (12%) in the rhGM-CSF group as opposed to 15 of 30 (50%) in the placebo group (P = 0.01). rhGM-CSF was well-tolerated. We conclude that rhGM-CSF was efficacious in accelerating myeloid recovery and reducing the length of hospitalization in febrile neutropenia.

Comparison of CA 19-9 and carcinoembryonic antigen (CEA) levels in the serum of patients with colorectal diseases

In this population‐based prospective follow‐up study, children undergoing solid organ transplantation had a highly elevated risk for fractures: The incidence of all fractures was 6‐fold higher (92 versus 14 fractures/1000 persons/year; p < 0.001) and vertebral fractures was 160‐fold higher (57 versus 0.35 fractures/1000 persons/year; p < 0.001) in the study group compared with the control population. Thus, screening of vertebral fractures at regular intervals is recommended, and preventive strategies should be studied.

Evaluation of CA 19-9 as a serum tumour marker in pancreatic cancer.

The serum levels of CA 19-9 and carcinoembryonic antigen (CEA) were determined in 37 patients with benign colorectal diseases and in 111 patients with newly discovered colorectal carcinomas or clinically verified relapses. In cancer patients, the CA 19-9 level ranged from normal (0-37 U ml-1) to 77,500 U ml-1 whereas all samples but one from patients with benign colorectal diseases had a normal value. CA 19-9 was increased in 46% and 45% of patients with an advanced (Dukes C or D) carcinoma or a verified recidive, respectively. Only one out of 26 patients (4%) with a localized (Dukes A or B) carcinoma displayed an elevated CA 19-9 level (greater than 37 U ml-1). No clear correlation was found between the CA 19-9 and CEA levels. The sensitivity of the CA 19-9 test (36%) was poorer than that of the CEA assay (69%), but the new test was markedly more specific (97% vs 70%) than the CEA assay.