A radiographic evaluation of facet sagittal angle in cervical spinal cord injury without major fracture or dislocation.

STUDY DESIGN: A retrospective radiographic study with a minimum 2-year follow-up. OBJECTIVE: To evaluate the relationships between the cervical articular facets' morphology and the incidence of traumatic cervical spinal cord injury (CSCI) without major fracture or dislocation. SETTING: Spinal Injuries Center, Japan. METHODS: This study included 113 patients with traumatic CSCI without major fracture or dislocation. Eighty-four healthy volunteers without neurological deficits or cervical cord pathology on magnetic resonance imaging (MRI) were defined as control subjects. We used a plain sagittal radiograph to measure the facet sagittal angles (FSA) at four cervical segments in all the CSCI patients and controls. We defined the FSA as the angle between the inferior margin of the superior cervical spinal body and the inferior articular process of the superior vertebra. RESULTS: Most frequent incidence of CSCI was seen at C3-4 segment (54%). With respect to CSCI at C3-4 segment, 55.7% of the subjects showed smallest FSA at C3-4 segment. CONCLUSION: Most of the traumatic CSCI at C3-4 segment showed raised cervical articular facets at C3-4 segment. On the basis of our results, we hypothesized that the raised cervical articular facets might have an important role in the etiology of traumatic CSCI. The cervical spinal cord at the C3-4 segment might receive the highest load during acute hyperextension of the cervical spine because of the C3-4 articular facets' morphology.

The potential for functional recovery of upper extremity function following cervical spinal cord injury without major bone injury.

STUDY DESIGN: This was a retrospective observational study. OBJECTIVES: The objectives were to describe the prognosis of upper extremity function following cervical spinal cord injury (CSCI), and to identify prognostic factors for functional recovery. SETTING: Spinal Injuries Center, Japan. METHODS: Sixty patients with C3-4 CSCI without major bone injury participated in the study. Patients were treated nonsurgically and evaluated using the American Spinal Injury Association (ASIA) scales for the upper and lower extremities, their residual cervical motor functions, the modified Frankel grade and an upper extremity function scale. We compared the findings for the upper extremity function scale at 6 months with those for the residual cervical motor functions and modified Frankel grade obtained 3 days after injury. RESULTS: Most patients with CSCI who could flex their hip and knee from a supine position (95%) or who showed some active elbow extension (86%) 3 days after their injury could use a spoon at 6 months. We compared patients who used their fingers at 6 months to those who could not, and observed significant differences in age and ASIA scores for the upper and lower extremities obtained 3 days after injury. A strong correlation was observed between the initial motor scores and the extent of functional recovery at 6 months. CONCLUSION: Hip and knee flexion from the supine position and elbow extension 3 days after injury significantly predicted a positive prognosis for upper extremity function. Younger age and higher ASIA motor scores obtained 3 days after injury were factors associated with neurological recovery.

A screen for potential ferredoxin electron transfer partners uncovers new, redox dependent interactions.

Ferredoxin (Fd) is the primary soluble acceptor at the end of the photosynthetic electron transport chain, and is known to directly transfer electrons to a wide range of proteins for use in metabolism and regulatory processes. We have conducted a screen to identify new putative Fd interaction partners in the cyanobacteria Synechocystis sp. PCC 6803 using Fd-chromatography in combination with MALDI-TOF mass spectrometry. Many novel interactions were detected, including several redox enzymes, which are now candidates for further experiments to investigate electron transfer with Fd. In addition, some proteins with regulatory activity related to photosynthesis were identified. We cloned and expressed one such protein, known as RpaA, which is a specific regulator of energy transfer between phycobilisomes and PSI. Using the recombinant protein we confirmed direct interaction with Fd, and discovered that this was dependent on redox state. The screen for putative Fd-binding proteins was repeated, comparing oxidizing and reducing conditions, identifying many proteins whose interaction with Fd is redox dependent. These include several additional signaling molecules, among them the LexA repressor, Ycf53 and NII, which are all involved in interpreting the redox state of the cell.

IgA nephropathy in a patient with systemic lupus erythematosus.

Systemic lupus erythematosus is generally recognized to be a multisystem autoimmune disease with kidney involvement. However, the occurrence of other non-lupus glomerulopathies has been rarely reported in patients with systemic lupus erythematosus. It is well known that lupus nephritis may switch over time to another class according to the World Health Organization classification. It seems likely that IgA nephropathy is a clinical characteristic of a particular subset of patients with systemic lupus erythematosus. We report a 22-year-old Japanese man with recurrence of proteinuria. The renal flare occurred when he was without lupus clinical and serological activity, and renal remission was only obtained with angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker therapy. Although the incidence of IgA nephropathy is high in Japan, we believe that this is the first report of a Japanese patient in which lupus nephritis switched over time to IgA nephropathy.

The reversible modification regulates the membrane-binding state of Apg8/Aut7 essential for autophagy and the cytoplasm to vacuole targeting pathway.

Autophagy and the Cvt pathway are examples of nonclassical vesicular transport from the cytoplasm to the vacuole via double-membrane vesicles. Apg8/Aut7, which plays an important role in the formation of such vesicles, tends to bind to membranes in spite of its hydrophilic nature. We show here that the nature of the association of Apg8 with membranes changes depending on a series of modifications of the protein itself. First, the carboxy-terminal Arg residue of newly synthesized Apg8 is removed by Apg4/Aut2, a novel cysteine protease, and a Gly residue becomes the carboxy-terminal residue of the protein that is now designated Apg8FG. Subsequently, Apg8FG forms a conjugate with an unidentified molecule "X" and thereby binds tightly to membranes. This modification requires the carboxy-terminal Gly residue of Apg8FG and Apg7, a ubiquitin E1-like enzyme. Finally, the adduct Apg8FG-X is reversed to soluble or loosely membrane-bound Apg8FG by cleavage by Apg4. The mode of action of Apg4, which cleaves both newly synthesized Apg8 and modified Apg8FG, resembles that of deubiquitinating enzymes. A reaction similar to ubiquitination is probably involved in the second modification. The reversible modification of Apg8 appears to be coupled to the membrane dynamics of autophagy and the Cvt pathway.

A case with spontaneous bladder rupture mimicking acute kidney injury.

A 77-year-old female with abdominal pain and ascites was admitted to our hospital. She had a past history of the postoperative pelvic irradiation for uterine cancer and subsequently suffered from neurogenic bladder. On admission, serum creatinine (s-Cr) and blood urea nitrogen (BUN) were elevated to 9.9 mg/dl and 131 mg/dl, respectively. However, both the ratio of BUN/s-Cr and creatinine in ascites/s-Cr were significantly elevated. The clinical manifestations of the present case were not typical for acute kidney injury. Furthermore, 2 days after urethral catheterization, both s-Cr and BUN were normalized (0.69 mg/dl and 10 mg/dl, respectively) and her symptoms had improved immediately. Therefore, we diagnosed her disease as spontaneous bladder rupture. We report a case with spontaneous bladder rupture mimicking acute kidney injury forty years after postoperative pelvic irradiation for uterine cancer.

Facial nerve motor-evoked potential monitoring during skull base surgery predicts facial nerve outcome.

OBJECTIVE: To determine whether monitoring facial nerve motor-evoked potentials (FNMEPs) elicited by transcranial electrical stimulation during skull base tumour surgery is useful for predicting facial nerve outcome. METHODS: This study analysed FNMEP findings in 26 patients with skull base tumours. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (180-550 V). FNMEPs were recorded from the orbicularis oculi and oris muscles. The correlation between the final-to-baseline FNMEP ratio and postoperative facial nerve function was examined. RESULTS: Postoperative facial nerve function correlated significantly with the FNMEP ratios in the orbicularis oculi (p = 0.004) and orbicularis oris (p<0.001) muscles. An FNMEP ratio of <50% consistently predicted immediate postoperative facial palsy, although the degree of palsy differed among patients. All patients had satisfactory facial nerve function (House and Brackmann grades I and II) postoperatively if the FNMEP ratio remained at >50%. CONCLUSIONS: Intraoperative FNMEP monitoring can be useful for predicting facial nerve function after skull base surgery. This new method is a valuable adjunct to conventional facial nerve monitoring.

Suppression of tumorigenicity, but not anchorage independence, of human cancer cells by new candidate tumor suppressor gene CapG.

Previously, we isolated a series of cell lines from a human diploid fibroblast lineage as a model for multistep tumorigenesis in humans. After passaging a single LT-transfected fibroblast clone, differently progressed cell lines were obtained, including immortalized, anchorage-independent and tumorigenic cell lines. In the present paper, we analysed the gene expression profiles of these model cell lines, and observed that expression of the CapG protein was lost in the tumorigenic cell line. To examine the possibility that loss of CapG protein expression was required for tumorigenic progression, we transfected CapG cDNA into the tumorigenic cell line and tested for tumor-forming ability in nude mice. Results showed that ectopic expression of CapG suppressed tumorigenicity, but not growth in soft agar or liquid medium. We also found that certain cancer cell lines including stomach cancer, lung cancer and melanoma had also lost CapG expression. One such cancer cell line AZ521 also became non-tumorigenic after the introduction of CapG cDNA. Moreover, we showed that CapG expression was repressed in small-cell lung cancer tissues. Together, our findings indicated that CapG is a new tumor suppressor gene involved in the tumorigenic progression of certain cancers.

Human corticotropin-releasing factor plus lysine vasopressin test during glucocorticoid therapy.

1.0 micrograms/kg body wt human corticotropin-releasing factor (hCRF) and 0.005 IU/kg body wt lysine vasopressin (LVP) were administered in a bolus dose to patients receiving daily or alternate-day glucocorticoid therapy. In normal subjects with this hCRF-LVP test, the plasma ACTH increment was significantly greater (approximately 2.5-fold) 15 min after injection than under the CRF test. In patients receiving daily glucocorticoid therapy (greater than 15 mg prednisolone or an equivalent daily dose), the plasma ACTH and cortisol responses to hCRF-LVP were suppressed 2 wk to 1 mo after the beginning of glucocorticoid administration but partially improved at 2-10 mo, and was markedly suppressed several years later. On the other hand, in patients receiving alternate-day glucocorticoid therapy, the plasma ACTH response was normal at 2 wk, normal or higher at 1-3 mo, and normal after 4 mo. A normal plasma cortisol response was observed throughout the test period in patients receiving alternate-day therapy after pulse therapy, whereas plasma cortisol response was gradually improved in patients receiving alternate-day therapy after several months of daily therapy.

CLOCK gene T3111C polymorphism is associated with Japanese schizophrenics: a preliminary study.

The CLOCK gene has attracted attention due to its influence on the circadian rhythm, as well as its impacts on the dopaminergic system. We conducted a preliminary study to examine whether the T3111C single nucleotide polymorphism of the CLOCK gene is associated with the development of schizophrenia by examining samples from schizophrenics (n=145) and normal controls (n=128). Both genotype and allele frequencies were significantly different between schizophrenics and controls (p=0.022, p=0.015, respectively). Schizophrenics had a significantly higher frequency of the C allele compared to controls (odds ratio 1.76, 95% CI 1.12-2.75). In particular, disorganized and residual type schizophrenics had significantly higher C allele frequencies than controls (p=0.004 and p=0.037, respectively). Our results suggest that the T3111C polymorphism of the CLOCK gene is associated with schizophrenia. It is important to explore the association between CLOCK and dopamine function, and to examine the impact of CLOCK on phenotypes such as symptoms and drug response in patients with schizophrenia.

Suppressive effects of dehydroepiandrosterone and the nuclear factor-kappaB inhibitor parthenolide on corticotroph tumor cell growth and function in vitro and in vivo.

Dehydroepiandrosterone (DHEA) is believed to have an anti-tumor effect, as well as anti-inflammatory, antioxidant, and anti-aging effects. To clarify the possible inhibitory action of DHEA on pituitary tumor cells, we tested the effects of DHEA, alone or in combination with the nuclear factor-kappaB (NF-kappaB) inhibitor parthenolide (PRT), on AtT20 corticotroph cell growth and function both in vitro and in vivo. We found that, in vitro, DHEA and PRT had potent inhibitory effects on pro-opiomelanocortin and NF-kappaB-dependent gene expression. They also suppressed the transcription activity of survivin, a representative anti-apoptotic factor, and induced apoptosis in this cell line. Furthermore, using BALB/C nude mice with xenografts of AtT20 cells in vivo, we found that the combined administration of DHEA and PRT significantly attenuated tumor growth and survivin expression. The treatment also decreased the elevated plasma corticosterone levels and ameliorated the malnutrition induced by tumor growth. Altogether, these results suggested that combined treatments of DHEA and PRT potently inhibit the growth and function of corticotroph tumor cells both in vitro and in vivo. This effect may, at least partly, be caused by the suppressive effects of these compounds, such as survivin and other inhibitor of apoptosis proteins, on NF-kappaB-mediated gene transcription.

Purinergic receptor ligands stimulate pro-opiomelanocortin gene expression in AtT-20 pituitary corticotroph cells.

Although recent studies have suggested that purinergic receptors are expressed in the anterior pituitary gland, their involvement in the regulation of pituitary hormone gene expression is not completely understood. In the present study, we examined the expression of purinergic receptors and the effects of purinergic receptor ligands on pro-opiomelanocortin (POMC) gene expression, in AtT20 mouse corticotroph cells. We identified the expression of most of the purinergic receptor subtypes (A1, A2, P2X1, 3-7, P2Y1, 2, 4) mRNAs, analysed by the reverse transcriptase-polymerase chain reaction. We also found that adenosine and ATP, two representative and endogenous agonists of A1-3 and P2X/P2Y receptors, respectively, stimulated the 5'-promoter activity of the POMC gene in a dose- and time-related manner. When these ligands were simultaneously used with corticotrophin-releasing hormone (CRH), effects that were more than additive were observed, suggesting an enhancing role of these compounds in CRH-mediated adrenocorticotrophic hormone (ACTH) synthesis. These ligands also stimulated the expression of transcription factors involved in the regulation of the POMC gene, but did not enhance ACTH secretion. Finally, the positive effect of adenosine as well as CRH was completely inhibited by the protein kinase A inhibitor H89, whereas that of ATP was not influenced, indicating that different intracellular signalling pathways mediate these effects. Altogether, our results suggest a stimulatory role for these purinergic receptor ligands in the regulation of POMC gene expression in corticotroph cells. Because adenosine and ATP are known to be produced within the pituitary gland, it is possible they may be acting in an autocrine/paracrine fashion.

High resolution NMR measurements using a 400MHz NMR with an (RE)Ba2Cu3O7-x high-temperature superconducting inner coil: Towards a compact super-high-field NMR.

Use of high-temperature superconducting (HTS) inner coils in combination with conventional low-temperature superconducting (LTS) outer coils for an NMR magnet, i.e. a LTS/HTS NMR magnet, is a suitable option to realize a high-resolution NMR spectrometer with operating frequency >1GHz. From the standpoint of creating a compact magnet, (RE: Rare earth) Ba2Cu3O7-x (REBCO) HTS inner coils which can tolerate a strong hoop stress caused by a Lorentz force are preferred. However, in our previous work on a first-generation 400MHz LTS/REBCO NMR magnet, the NMR resolution and sensitivity were about ten times worse than that of a conventional LTS NMR magnet. The result was caused by a large field inhomogeneity in the REBCO coil itself and the shielding effect of a screening current induced in that coil. In the present paper, we describe the operation of a modified 400MHz LTS/REBCO NMR magnet with an advanced field compensation technology using a combination of novel ferromagnetic shimming and an appropriate procedure for NMR spectrum line shape optimization. We succeeded in obtaining a good NMR line shape and 2D NOESY spectrum for a lysozyme aqueous sample. We believe that this technology is indispensable for the realization of a compact super-high-field high-resolution NMR.

CD133 and DNA-PK regulate MDR1 via the PI3K- or Akt-NF-κB pathway in multidrug-resistant glioblastoma cells in vitro.

Chemotherapy is an adjuvant treatment for glioblastomas, however, chemotherapy remains palliative because of the development of multidrug resistance (MDR). Following prolonged chemotherapy, MDR protein 1 (MDR1) and CD133 increase in recurrent glioblastomas. CD133 positive (CD133+) glioma cancer stem-like cells (GCSCs) markedly promote drug resistance and exhibit increased DNA damage repair capability; thus they have a key role in determining tumor chemosensitivity. Although CD133, DNA-dependent protein kinase (DNA-PK), and MDR1 are elevated in CD133+ GCSCs, the relationship among these molecules has not been elucidated. In this study, MDR glioblastoma cell lines were created in response to prolonged doxorubicin chemotherapy. CD133, DNA-PK and MDR1 were markedly elevated in these cells. CD133 and DNA-PK may increase MDR1 via the phosphatidylinositol-3-kinase (PI3K)-Akt signal pathway. PI3K downstream targets Akt and nuclear factor (NF)-κB, which interacts with the MDR1 promoter, were also elevated in these cells. Downregulation of CD133 and DNA-PK by small interfering RNA, or inhibition of PI3K or Akt, decreased Akt, NF-κB and MDR1 expression. The results indicate that CD133 and DNA-PK regulate MDR1 through the PI3K- or Akt-NF-κB signal pathway. Consequently, a novel chemotherapeutic regimen targeting CD133 and DNA-PK in combination with traditional protocols may increase chemotherapeutic efficacy and improve prognosis for individuals who present with glioblastoma.

Suicide inactivation of porcine leukocyte 12-lipoxygenase associated with its incorporation of 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid derivative.

Two isozymes of arachidonate 12-lipoxygenase, platelet-type and leukocyte-type, which were distinguished by their substrate specificities and primary structures, were investigated with reference to 'suicide' inactivation. Upon reaction with arachidonic acid the leukocyte-type enzyme was inactivated rapidly during the catalysis, whereas the platelet-type enzyme did not show such a rapid inactivation. The two 12-lipoxygenase isozymes were incubated with various hydroperoxy and hydroxy products from arachidonic acid. (15S)-Hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) was found to be a unique substrate of the leukocyte-type 12-lipoxygenase as follows. (1) 15-HPETE was an active substrate for porcine leukocyte 12-lipoxygenase, and converted anaerobically to a 14,15-epoxy compound (14,15-leukotriene A4). (2) A rapid inactivation of the enzyme was observed within 2 min upon aerobic and anaerobic incubations with 15-HPETE. (3) 15-HPETE was rapidly incorporated into the enzyme in a nearly equimolar amount under both aerobic and anaerobic conditions. (4) Several findings suggested a covalent binding of 15-HPETE or its derivative to the enzyme. (5) Such a rapid and stoichiometric incorporation of 15-HPETE was not observed with the platelet-type 12-lipoxygenase. On the basis of these findings we presumed that 15-HPETE was transformed to 14,15-leukotriene A4, which was covalently bound to the leukocyte-type 12-lipoxygenase leading to the suicide inactivation of the enzyme.

Comparative study on evaluation methods for serum testosterone level for PADAM diagnosis.

The International Society for the Study of the Aging Male (ISSAM) recommends that a diagnosis be based on a patient's total testosterone (TT), calculated free testosterone (cFT), or calculated bioavailable testosterone (cBT) for partial androgen deficiency of the aging male (PADAM). The purpose of this study was to confirm whether hypogonadism of patients with PADAM is related to symptoms and clarify which criteria of testosterone recommended by ISSAM is suitable for Japanese patients. A total of 90 patients with PADAM symptoms were included in this study. Endocrinologic profiles were reviewed as appropriate, and PADAM symptoms were judged by means of several questionnaires. Laboratory values and symptoms were compared between patients with and without hypogonadism. Even when any criterion of testosterone was used for diagnosis of hypogonadism, AMS (total and subscales), IIEF-5, or SDS scores of PADAM symptoms did not differ significantly between patients classified as having and not having hypogonadism. No other endocrinologic variables than testosterone differed significantly between them, either. PADAM symptoms are not related to testosterone level and it is still obscure whether ISSAM's criterion can be adopted for Japanese patients with PADAM. Other pathology needs to be addressed for evaluation and diagnosis of PADAM in Japan.

Whether or not prophylactic excision of the extrahepatic bile duct is appropriate for patients with pancreaticobiliary maljunction without bile duct dilatation.

BACKGROUND/AIMS: The standard treatment for patients with a pancreaticobiliary maljunction (PBM) without bile duct dilatation remains controversial. METHODOLOGY: We followed up 29 patients with such PBM who mainly underwent a cholecystectomy alone. The ages of the patients ranged from 3 to 76 years (average age 47.3 years) and the ratio of males to females was 8 vs. 21. When the diameter of the common bile duct was less than 10mm, such bile ducts were diagnosed to have no dilatation. The main clinical indications for surgery were cholecystolithiasis in 15 patients, choledocholithiasis in 3, cholecystocholedocholithiasis in 2, gallbladder polyp in 2, adenomyomatosis in 2, cholecystitis in 2, and protein plug in 1. RESULTS: The amylase levels of gallbladder bile in 20 patients ranged from 115 to 460,200 IU/mL (a mean of 191,698 IU/mL). One patient died of gastric cancer 182 months after surgery and two patients died of other diseases 153, 171 months after surgeries, respectively. The remaining 26 patients have all been doing well for 36 months to 326 months after surgery (a median follow-up period, 160.5 months). The 10- and 15-year survival rates were 100% and 89.7%. CONCLUSIONS: In conclusion, a prophylactic resection of the extrahepatic bile duct and biliary diversion could be unnecessary for patients with PBM without bile duct dilatation.

Reciprocal modulation of interleukin-1 beta (IL-1 beta) and IL-1 receptors by lipopolysaccharide (endotoxin) treatment in the mouse brain-endocrine-immune axis.

The cytokine interleukin-1 (IL-1) alters a variety of immune, central nervous system, and neuroendocrine activities characteristic of an integrator of the brain-endocrine-immune response to stress. In an attempt to define the regulation of IL-1 and IL-1 receptors in the mouse brain-endocrine-immune axis, we measured tissue levels of IL-1 beta using an enzyme-linked immunosorbent assay and iodine-125-labeled recombinant human IL-1 alpha ([125I]IL-1 alpha) binding in hippocampus, hypothalamus, pituitary, epididymus, testis, and spleen after ip injection of the bacterial endotoxin lipopolysaccharide (LPS). Basal IL-1 beta levels were detectable in all of the tissues examined. IL-1 beta levels were dramatically increased in the peripheral tissues (pituitary, testis, and spleen) 2-6 h after a single LPS injection; however, no significant changes were observed in the brain (hippocampus and hypothalamus). [125I]IL-1 alpha binding was decreased in the spleen, but was unchanged in the hippocampus and testis after a single LPS injection. To determine whether activation of IL-1 in brain may require more sustained exposure to endotoxin, we examined the effects of two injections of LPS at 0 and 12 h. After two LPS injections (0 and 12 h), significant increases in IL-1 beta concentrations were noted in the hippocampus, hypothalamus, spleen, testis and epididymus; [125I]IL-1 alpha binding using quantitative autoradiography was significantly decreased in all tissues, including the pituitary gland. Saturation studies in whole testis homogenates demonstrated that the LPS-induced decrease in [125I]IL-1 alpha binding was primarily due to a decrease in the density of IL-1 receptors. These data demonstrate that LPS treatment results in elevated circulating and/or tissue levels of IL-1, which, in turn, down-regulates IL-1 receptors in the brain-endocrine-immune axis.

Interleukin-1 receptors in mouse kidney: identification, localization, and modulation by lipopolysaccharide treatment.

The cytokine interleukin-1 (IL-1) has a variety of effects in the kidney involving induction of nephritis and renal injury. In addition, recent reports suggest that IL-1 regulates natriuresis and renin secretion in the kidney. To examine the potential sites of action of IL-1 in the kidney, we used iodine-125-labeled recombinant human interleukin-1 alpha ([125I]IL-1 alpha) to identify and characterize IL-1 receptors in crude membrane preparations of mouse (C57BL/6) kidney. The binding of [125I] IL-1 alpha was linear over a broad range of membrane protein concentrations, saturable, reversible, and of high affinity, with an equilibrium dissociation constant (Kd) of 66 +/- 10 pM and a maximum number of binding sites of 1.04 +/- 0.24 fmol/mg protein. In competition studies, recombinant human IL-1 alpha, recombinant human IL-1 beta, and a weak IL-1 beta analog (IL-1 beta+) inhibited [125I]IL-1 alpha binding to mouse kidney in parallel with their relative bioactivities in the T-cell comitogenesis assay, with inhibitory binding affinity constant (Ki) values of 28 +/- 19, 53 +/- 23, and 5560 +/- 2098 pM, respectively; rat/human CRF and human tumor necrosis factor had no effect on [125I]IL-1 alpha binding. In autoradiographic studies, IL-1 receptors were heterogeneously distributed in the kidney, with significantly higher densities present in the medulla than in the cortex. To study the effects of endogenous IL-1 in modulating [125I]IL-1 alpha-binding sites in kidney, we injected 30 micrograms of the bacterial endotoxin lipopolysaccharide (LPS) to mice ip. Autoradiographic studies demonstrated substantial decreases in [125I]IL-1 alpha binding in both the kidney cortex (control, 34.7 +/- 6.2 fmol/mg tissue equivalent; LPS, 11.3 +/- 0.3; P less than 0.05) and medulla (52.7 +/- 8.1 vs. 26.0 +/- 1.0; P less than 0.05) 24 h after injection of LPS. Saturation studies in whole kidney homogenates demonstrated that the LPS-induced decrease in [125I]IL-1 alpha binding was primarily due to a down-regulation of IL-1 receptors (i.e. decrease in the maximum number of binding sites). The identification of IL-1 receptors in kidney with characteristics similar to those of IL-1 receptors in the brain-endocrine-immune axis provides further support for a physiological role for IL-1 in regulating renal function.