Plasma levels of interleukin-1 receptor antagonist (IL1Ra) predict radiographic progression of symptomatic knee osteoarthritis.

OBJECTIVE: Pro- and anti-inflammatory mediators, such as IL-1ß and IL1Ra, are produced by joint tissues in osteoarthritis (OA), where they may contribute to pathogenesis. We examined whether inflammatory events occurring within joints are reflected in plasma of patients with symptomatic knee osteoarthritis (SKOA). DESIGN: 111 SKOA subjects with medial disease completed a 24-month prospective study of clinical and radiographic progression, with clinical assessment and specimen collection at 6-month intervals. The plasma biochemical marker IL1Ra was assessed at baseline and 18 months; other plasma biochemical markers were assessed only at 18 months, including IL-1ß, TNFα, VEGF, IL-6, IL-6Rα, IL-17A, IL-17A/F, IL-17F, CRP, sTNF-RII, and MMP-2. RESULTS: In cross-sectional studies, WOMAC (total, pain, function) and plasma IL1Ra were modestly associated with radiographic severity after adjustment for age, gender and body mass index (BMI). In addition, elevation of plasma IL1Ra predicted joint space narrowing (JSN) at 24 months. BMI did associate with progression in some but not all analyses. Causal graph analysis indicated a positive association of IL1Ra with JSN; an interaction between IL1Ra and BMI suggested either that BMI influences IL1Ra or that a hidden confounder influences both BMI and IL1Ra. Other protein biomarkers examined in this study did not associate with radiographic progression or severity. CONCLUSIONS: Plasma levels of IL1Ra were modestly associated with the severity and progression of SKOA in a causal fashion, independent of other risk factors. The findings may be useful in the search for prognostic biomarkers and development of disease-modifying OA drugs.

"Design of a Suspension Lever Mechanism in Biomedical Robotic System".

The article discusses the design of a suspended lever mechanism with elastic elements, which is used as a safety device in a robotic system for the rehabilitation of the lower limbs. The article analyzes the existing mechanical structures of devices for rehabilitation, identifies the problems of operation, design, and safety systems and suggests a new design of the device. The process of reverse development of a lever mechanism scheme to ensure safety during rehabilitation of the lower limbs is presented. The design of the lever mechanism consists of movable levers connected by elastic elements. The device allows you to dampen the force during active rehabilitation. The power calculation of the lever mechanism in the rehabilitation system was carried out. The article addresses the issues present in the current mechanical designs with a brief discussion on the system architecture.

Expression of the kidney injury molecule 1 in the rat cochlea and induction by cisplatin.

Cisplatin is a widely used chemotherapeutic agent whose dose-limiting side effects include ototoxicity and nephrotoxicity. Recent evidence indicates that cisplatin induces the expression of a novel protein, kidney injury molecule-1, in the renal proximal tubular epithelium to aid in regeneration. In this study, we determined whether kidney injury molecule-1 is expressed in the cochlea and is induced by cisplatin. Using reverse transcriptase polymerase chain reaction techniques, we have now identified kidney injury molecule-1 in the rat cochlea and in three different mouse transformed hair cell lines. Administration of cisplatin to rats produced hearing loss and induced kidney injury molecule-1 mRNA in the rat cochlea. Pretreatment of rats with lipoic acid, a scavenger of reactive oxygen species, significantly reduced cisplatin-induced hearing loss and kidney injury molecule-1 expression. Cisplatin also increased the expression of cochlear NOX3 mRNA, a member of the superoxide generating NADPH oxidase family of proteins recently identified in the cochlea, inhibition of which decreased kidney injury molecule-1 expression. Polymerase chain reaction performed on different regions of the cochlea indicated the presence of kidney injury molecule-1 mRNA in the lateral wall, organ of Corti and spiral ganglion. This distribution was confirmed by immunocytochemistry. Taken together, these data identify kidney injury molecule-1 as a novel cochlear injury molecule, whose expression is regulated by reactive oxygen species generated via the NADPH oxidase pathway.

Inhibition of glutathione-related enzymes and cytotoxicity of ethacrynic acid and cyclosporine.

Glutathione (GSH) is an endogenous thiol that detoxifies active oxygen and reactive species formed during intermediary metabolism and drug detoxification. Compounds with a range of potential toxicities were tested for their abilities to affect GSH reductase and GSH S-transferase activities, which are each components of the two principal detoxification pathways in which GSH participates. A high performance liquid chromatographic method for determining oxidized and reduced GSH was modified to assay GSH reductase activity. With this method it was possible to demonstrate that ethacrynic acid, which inhibits GSH S-transferase, also inhibits the activity of GSH reductase. Inhibition of GSH reductase by ethacrynic acid was similar to that seen with carmustine (BCNU). GSH reductase activity was not affected by cis- or transplatin, buthionine sulfoximine, other loop diuretics, cyclosporine A or aminoglycosides. Cyclosporine inhibited GSH S-transferase at 50 microM and higher concentrations. These results support a role for GSH-mediated detoxification mechanisms in ethacrynic acid- and cyclosporine-associated cytotoxicity, which may mediate their toxicities and their potential as adjunctive agents in antineoplastic therapy. A better understanding of the mechanism of their toxicity can greatly extend the clinical usefulness of these agents, as this toxicity is the basis of both their therapeutic and antitherapeutic actions.

Comparison of cyclosporine and FK506 effects on glutathione levels in rat cochlea, brain, liver and kidney.

Cyclosporine treatment (50 mg/kg/day, p.o.) caused increases in rat renal reduced glutathione (GSH) levels of 205 and 673%, respectively, after 5 and 10 days. No changes were seen in liver GSH with either dose of cyclosporine. FK506 (2.5 mg/kg/day, p.o., for 7 days) caused an approximately 200% increase in kidney GSH, and an approximately 250% increase in hepatic GSH levels. Oxidized glutathione (GSSG) was never more than 1-2% of the level of the reduced form in any tissue from control animals. Small increases in the ratios of oxidized to reduced glutathione were seen in livers and kidneys from both cyclosporine- and FK506-treated animals. No changes in GSH or GSSG levels were seen in brains or cochleas from any animal.

Ototoxicity. Amelioration by protective agents.

The findings of studies from this laboratory are summarized to compare the efficacy of four chemoprotective agents against the effects of cisplatin-induced hearing loss and biochemical damage in the rat cochlea. A number of studies have shown that cisplatin is ototoxic, resulting in hearing loss, morphologic damage, and biochemical changes in the cochlea. These studies used Wistar rats, which underwent pre- and posttreatment ABR testing using clicks and tonebursts stimuli at 8, 16, and 32 kHz. Controls received i.p. saline injection. Cisplatin-treated rats were given 16 mg/kg cisplatin i.p. Animals received protective agents in the following dosage: DDTC protected rats received 600 mg/kg subcutaneously an hour after cisplatin. MTBA-protected animals were given 250 mg/kg i.p. 30 minutes before cisplatin. Animals protected with ebselen received 16 mg/kg i.p. an hour before cisplatin. One hundred mg/kg of alpha-lipoic acid was injected i.p. 30 minutes before cisplatin. Rats were sacrificed three days after treatment and the cochleae were harvested and frozen in liquid nitrogen and stored at -80 degrees C until analysis of glutathione (GSH), the activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and malondialdehyde was performed. Cisplatin-treated rats were found to have ABR threshold shifts of 27-40 dB, and rats treated with chemoprotective agents plus cisplatin all had ABR thresholds shifts of less than 10 dB. Significant depletion of glutathione and decrease of the activities of the antioxidant enzymes were observed in cisplatin-treated rats. These changes were accompanied by a marked elevation of malondialdehyde. These changes were almost completely prevented by the use of the chemoprotective agents. These findings suggest that cisplatin ototoxicity is related to lipid peroxidation and that the use of protective agents prevents hearing loss and lipid peroxidation by sparing the antioxidant defense system in the cochlea.

Dose dependent protection by lipoic acid against cisplatin-induced ototoxicity in rats: antioxidant defense system.

This study investigated the alterations that occur in auditory brainstem-evoked responses (ABRs) concurrent with changes in cochlear concentrations of glutathione (GSH), lipid peroxidation, and antioxidant enzyme activity in cisplatin-induced ototoxicity and in dose-dependent otoprotection by an antioxidant lipoate. Male Wistar rats were divided into different groups and were treated as follows, with: (1) vehicle (saline) control; (2) cisplatin (16 mg/kg, i.p.); (3) lipoate (100 mg/kg, i.p.) plus saline; (4) cisplatin plus lipoate (25 mg/kg); (5) cisplatin plus lipoate (50 mg/kg), and (6) cisplatin plus lipoate (100 mg/kg). Post-treatment ABRs were evaluated after three days, the rats were sacrificed, and cochleae were harvested and analyzed. The cisplatin-injected rats showed ABR threshold elevations above the pre-treatment thresholds. Rats treated with lipoate plus cisplatin did not show significant elevation of hearing thresholds. Cisplatin administration resulted in a depletion of cochlear GSH concentration (69% of control), whereas, cisplatin-plus-lipoate treatment increased GSH concentration close to control value. Cisplatin-treated rats showed a decrease in cochlear superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione reductase (GR) activities (57, 78, 59, and 58% of control, respectively), and an increase in malondialdehyde (MDA) concentration (196% of control). Cochlear SOD, CAT, GSH-Px, and GR activities and MDA concentrations were restored in the rats injected with cisplatin plus graded doses of lipoate than those with cisplatin alone. It is concluded that cisplatin-induced ototoxicity is related to impairment of the cochlear antioxidant defense system, and the dose-dependent otoprotection conferred by an antioxidant lipoate against cisplatin ototoxicity is associated with sparing of the cochlear antioxidant defense system.

Olfactory mucosal lesions following subcutaneous diethyldithiocarbamate (DDTC).

We found that a single 600 mg/kg subcutaneous dose of the chelating agent diethyldithiocarbamate (DDTC) in rats caused severe damage of the olfactory epithelium. Damage was characterized by degeneration of the receptor cells but sparing of basal cells. This degeneration was characterized centrally (in the olfactory bulb) by 50% shrinkage of glomeruli. Reactive gliosis, as judged by immunoreactivity for glial fibrillary acidic protein, was prominent in the glomeruli at one week. Glomeruli areas had recovered to control values and gliosis in glomeruli had decreased by five weeks after injection. This recovery corresponds to sparing of the regenerative cell of the olfactory epithelium. We hypothesized that DDTC may act by disrupting xenobiotic metabolic pathways requiring divalent cations.

Ototoxicity of indacrinone is stereospecific.

Indacrinone (MK-196) is a loop diuretic which consists of a racemic mixture. The purpose of this study was to evaluate the individual enantiomers in the chinchilla model to determine whether these compounds affect auditory function and whether a difference in ototoxic potency exists. Very little change of endocochlear potential (EP) or compound action potential (CAP) was noted in animals receiving the (+)-enantiomer. On the other hand, chinchillas injected with the (-)-enantiomer were found to have a dose related reduction in both CAP and EP. These findings suggest the possibility that the diuretic receptor in the kidney and the receptor mediating ototoxicity in the cochlea, may have similar steric requirements for interacting with loop diuretics.

Some organic acids attenuate the effects of furosemide on the endocochlear potential.

A series of organic acid transport inhibitors significantly reduced the endocochlear potential (EP) decline produced by furosemide in the chinchilla. Probenecid, sodium salicylate and penicillin G were much more effective than novobiocin, meclofenamate or diatrizoate. Inhibitors of organic base transport, choline and N-methyl nicotinamide, had no effect on the furosemide-induced drop of the EP. These findings suggest that at least part of furosemide ototoxicity may be mediated by organic acid transport.

Changes in endolymph chloride concentration following furosemide injection.

Endocochlear potential (EP) and chloride concentration in endolymph were monitored with microelectrodes in the basal turn of the cochlea of the chinchilla. After intravenous injection of furosemide (25-100 mg/kg), the EP dropped precipitously and rapidly reached its minimum value, however, the chloride activity in endolymph decreased more gradually. Possible mechanisms for this phenomenon include a reduced electrostatic attraction of chloride ions to the scala media due to a decreased EP and a reduction of passive influx of chloride into endolymph, resulting from a reduction of active inward potassium transport by furosemide.

Effect of furosemide upon endolymph potassium concentration.

Chinchillas were anesthetized with ketamine (40 mg/kg i.m.) and endocochlear potential (EP) and potassium concentration in endolymph (Ke+) were determined in control animals and in animals injected with various doses of furosemide (25, 50 or 100 mg/kg i.v.) by means of microelectrodes inserted into scala media. Control EP and Ke+ in the chinchilla were 81.3 +/- 3.8 mV and 158.5 +/- 3.2 mequiv./l, respectively. Following injection of furosemide, a dose-related fall in EP and Ke+ was observed. However, the EP declined much more rapidly than the Ke+, and recovered more quickly than the latter. The recovery of Ke+ tended to lag behind the EP recovery. The debate over whether potassium transport into endolymph and endocochlear potential generation are related or independent events is discussed in the light of recent literature and the present study.

Organic acids do not alter the cochlear effects of ethacrynic acid.

Previous studies have shown a reduction of the ototoxicity of furosemide in chinchillas pretreated with organic acid transport inhibitors. The current studies were designed to investigate whether such a protective effect could be observed in chinchillas receiving ethacrynic acid. Chinchillas weighing 400-600 g were injected with saline followed by ethacrynic acid 12.5 mg/kg i.v. (controls) or one of three organic acids (probenecid, penicillin G and or sodium salicylate) 50 mg/kg i.v., thirty minutes prior to ethacrynic acid injection (experimentals). Endocochlear potential (EP) and compound action potential of the eighth nerve (CAP) elicited by click stimuli were simultaneously monitored before and after injection in both groups. The mean change in EP and CAP findings are consistent with observations by other investigators of the actions of these loop diuretics in the isolated loop of Henle. In the latter tissues, the 'furosemide-like loop diuretics' appear to have a different mechanism of action than does ethacrynic acid. It appears from the findings of the present study that the actions of furosemide and ethacrynic acid on the cochlea are by different mechanisms as well.

Development of endocochlear potential and compound action potential in the rat.

The present study was designed to investigate the developmental changes of the endocochlear potential and compound action potential simultaneously from rat pups of various ages. Animals were anesthetized with ketamine/xylazine, and the endocochlear potential was measured with a glass microelectrode. At the same time, a wire electrode was placed on the round window to record the click-evoked compound action potential. The endocochlear potential was found to be very low during the first few days of postnatal life. A rapid increase in the value of the endocochlear potential was noted between eleven and thirteen days of age, and adult-like values were recorded by seventeen days of age. Compound action potential responses were recorded at thirteen days of age to high intensity clicks, followed by a progressive improvement of thresholds and reduction of latencies. The development of the endocochlear potential and compound action potential was found to be reciprocally related - as the magnitude of the endocochlear potential increased, the compound action potential threshold declined with increasing age. The development of the endocochlear potential was found to closely approximate the development of enzymatic activity of sodium, potassium-ATPase in the stria vascularis reported by Kuijpers (1974).

Effect of 4-methylthiobenzoic acid on cisplatin-induced ototoxicity in the rat.

The purpose of this study was to investigate the effectiveness of 4-methylthiobenzoic acid (MTBA) as a protection agent against cisplatin (CDDP)-induced changes in organ of Corti surface structure, compared to electrophysiological changes. Electrophysiological change was assessed using auditory brainstem response (ABR) and morphological changes were assessed using scanning electron microscopy (SEM). Male Wistar rats underwent pre-treatment ABRs in response to clicks, and tone bursts at 2, 4, 8, 16, and 32 kHz. The three groups of rats were injected as follows: (1) MTBA (250 mg/kg, i.p.), (2) CDDP (16 mg/kg, i.p.), (3) CDDP+MTBA (16 mg/kg, i.p. + 250 mg/kg, i.p.). Post-treatment ABRs were performed 3 days after drug administration and rats were sacrificed. Their cochleae were harvested and SEM was used to examine the surface of the organ of Corti, specifically the number of inner hair cells (IHCs) and outer hair cells (OHCs) in the apical, middle and basal turns of the cochlea. Animal weight was measured on the first and final days. There was a good correlation between ABR threshold changes and hair cell loss in the high frequency region of the cochlea (basal turn), while threshold changes in the lower test frequencies (middle turn) appeared to be the result of more subtle changes in the cochlea. MTBA provided effective protection against cisplatin-induced ABR threshold changes at all test frequencies as well as hair cell loss. MTBA also protected against body weight loss.

Acute changes in cochlear potentials due to cisplatin.

The purpose of this study was to investigate how the hair cells and stria vascularis are affected at the onset of cisplatin ototoxicity. The effects on the endocochlear potential (EP) and the cochlear microphonics (CM) were observed simultaneously in two groups of adult chinchillas receiving as follows: (1) 5 microl of cisplatin (1 mg/ml) in normal saline, and (2) 5 microl of normal saline on the round window. The EP and the CM were recorded for 12-14 h after cisplatin application, and morphological changes were assessed using scanning electron microscopy. Both the EP and the CM amplitude demonstrated a profound reduction, and a very strong correlation was observed between these two values during this time period. Although the reduction of the EP and the CM was observed by 12-14 h, only very slight degeneration of outer hair cells was seen at that time. These data suggested that a reduction of the EP which was caused by the alteration of the stria vascularis might be primarily responsible for very early changes in cochlear function after topical cisplatin application, while later changes were the direct result of hair cell damage.

Alteration of 6-phosphofructo-1-kinase subunits during neonatal maturation of the rat cochlear cells.

During postnatal development of rat cochlear cells and the onset of hearing (10-23 days), the increasing endocochlear potential and energy requirements are largely provided by increased glucose utilization. It is well established that the ability of maturing rat tissues to use glucose is directly related to alteration of 6-phosphofructo-1-kinase (PFK) subunits. To gain insight into the alteration of PFK subunit levels in the cochlea from 6 to 60 days of age, PFK subunit types were measured in sections of paraffin-embedded temporal bone using IgG specific for each type of PFK subunit and quantified by computer image analysis. Although the L-type and C-type subunits did not exhibit statistically significant changes in the cochlear structures during maturation, the levels of M-type subunit in the stria vascularis cells, spiral ligament cell types I, II, and III, outer hair cells, inner hair cells, and support cells significantly increased. Also, the type IV and V spiral ligament fibrocytes during this period did not exhibit significant alterations of the M-type subunit. These data suggest that during neonatal development of the cochlear, the elevated levels of the M-type subunit are associated with increased glucose utilization and the onset of hearing.

Effects of organic acids on the edema of the stria vascularis induced by furosemide.

Furosemide is a loop diuretic which is ototoxic. Investigations have shown the stria vascularis to be the target tissue of this ototoxic drug. The purpose of the present study was to investigate the effects of furosemide on the stria vascularis in chinchillas, in controls and in animals pretreated with the above organic acids. Control animals were injected with 0.5 ml alkalinized saline followed by furosemide IV 30 min later. Experimental animals received probenecid, penicillin or sodium salicylate IV. Thirty minutes later, furosemide was injected in the same dose as in the controls. The basal turn of the stria vascularis was rapidly removed at various times from 10 to 30 min after furosemide administration and processed for transmission electron microscopy. Control animals were found to have reversible edema of the stria vascularis. Experimental animals had variable findings. Those animals pretreated with penicillin had virtually no edema of the stria vascularis at any time. Salicylate and probenecid pretreated animals had significantly less edema from one to 10 min after furosemide injection, but more edema than controls at later times. These findings suggest a discrepancy between ultrastructural pathology and functional status of the cochlea in experimental animals pretreated with probenecid or sodium salicylate followed by furosemide. On the other hand, good structure function correlations were seen in controls and in experimental animals pretreated with penicillin.

Time response of carboplatin-induced hearing loss in rat.

Carboplatin is currently being used as an anticancer drug against human cancers. However, high dose of carboplatin chemotherapy resulted in hearing loss in cancer patients. We have shown that carboplatin-induced hearing loss was related to dose-dependent oxidative injury to the cochlea in rat model. However, the time response of ototoxic dose of carboplatin on hearing loss and oxidative injury to cochlea has not been explored. The aim of the study was to evaluate the time response of carboplatin-induced hearing loss and oxidative injury to the cochlea of the rat. Male Wistar rats were divided into two groups of 30 animals each and treated as follows: (1) control (normal saline, i.p.) and (2) carboplatin (256 mg/kg, a single i.p. bolus injection). Auditory brain-evoked responses (ABRs) were recorded before and 1-5 days after treatments. The animals (n = 6) from each group were sacrificed on day 1, 2, 3, 4, and 5 and cochleae were isolated and analyzed. Carboplatin significantly elevated the hearing thresholds to clicks and to 2, 4, 8, 16, and 32 kHz tone burst stimuli only 3-5 days post-treatment. Carboplatin significantly increased nitric oxide (NO), malondialdehyde (MDA) levels and manganese superoxide dismutase (Mn-SOD) activity in the cochlea 4-5 and 3-5 days post-treatment, respectively, indicating enhanced influx of free radicals and oxidative injury to the cochlea. Carboplatin significantly depressed the reduced to oxidized glutathione (GSH/GSSG) ratio, antioxidant enzyme activities such as copper/zinc-superoxide dismutase (CuZn-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) as well as enzyme protein expressions in the cochlea 3-5 days after treatment. The data suggest that carboplatin-induced hearing loss involves oxidative injury to the cochlea of the rat in a time-dependent manner.