Cochlear and neural delays for coincidence detection in owls.

The auditory system uses delay lines and coincidence detection to measure the interaural time difference (ITD). Both axons and the cochlea could provide such delays. The stereausis theory assumes that differences in wave propagation time along the basilar membrane can provide the necessary delays, if the coincidence detectors receive input from fibers innervating different loci on the left and right basilar membranes. If this hypothesis were true, the left and right inputs to coincidence detectors should differ in their frequency tuning. The owl's nucleus laminaris contains coincidence detector neurons that receive input from the left and right cochlear nuclei. Monaural frequency-tuning curves of nucleus laminaris neurons showed small interaural differences. In addition, their preferred ITDs were not correlated with the interaural frequency mismatches. Instead, the preferred ITD of the neuron agrees with that predicted from the distribution of axonal delays. Thus, there is no need to invoke mechanisms other than neural delays to explain the detection of ITDs by the barn owl's laminaris neurons.

Susceptibility and negative epistatic loci contributing to type 2 diabetes and related phenotypes in a KK/Ta mouse model.

The KK/Ta mouse strain serves as a suitable polygenic model for human type 2 diabetes. Using 93 microsatellite markers in 208 KK/Ta x (BALB/c x KK/Ta)F1 male backcross mice, we carried out a genome-wide linkage analysis of KK/Ta alleles contributing to type 2 diabetes and related phenotypes, such as obesity and dyslipidemia. We identified three major chromosomal intervals significantly contributing to impaired glucose metabolism: one quantitative trait locus for impaired glucose tolerance on chromosome 6 and two loci for fasting blood glucose levels on chromosomes 12 and 15. The latter two loci appeared to act in a complementary fashion. Two intervals showed significant linkages for serum triglyceride levels, one on chromosome 4 and the other on chromosome 8. The KK allele on chromosome 8 acts to promote serum triglyceride levels, whereas the KK allele on chromosome 4 acts to suppress this effect in a recessive fashion. In addition, it is suggested that the chromosome 4 locus also acts to downregulate body weight and that the chromosome 8 locus acts to upregulate serum insulin levels. Our data clearly showed that each disease phenotype of type 2 diabetes and related disorders in KK/Ta mice is under the control of separate genetic mechanisms. However, there appear to be common genes contributing to different disease phenotypes. There are potentially important candidate genes that may be relevant to the disease.

Efficient asymmetric synthesis of alpha-trifluoromethyl-substituted primary amines via nucleophilic 1,2-addition to trifluoroacetaldehyde SAMP- or RAMP-hydrazone.

[reaction: see text] An efficient asymmetric synthesis of alpha-trifluoromethyl-substituted primary amines via nucleophilic 1,2-addition of alkyllithium reagents to trifluoroacetaldehyde SAMP- or RAMP-hydrazone followed by benzoylation and SmI(2)-promoted nitrogen-nitrogen single bond cleavage is described.

Retarded vestibular compensation in mutant mice deficient in delta 2 glutamate receptor subunit.

The delta 2 subunit of ionotropic glutamate receptors is expressed only in the cerebellar Purkinje cell. In mutant mice deficient in the delta 2 protein, cerebellar long-term depression and motor coordination are impaired. We examined behavioural plasticity in these mutant mice after unilateral vestibular destruction. After intratympanic injection of sodium arsanilate, the mice showed roll head tilt and their righting response under a rotation load was impaired. These symptoms improved with time. However, compensation of the righting response was retarded in the mutant mice. These results suggest that motor learning of the delta 2 mutant mice is disturbed, and that the static and dynamic components of vestibular compensation may be controlled by different neuronal mechanisms.

Voltage-gated ionic currents and their roles in timing coding in auditory neurons of the nucleus magnocellularis of the chick.

Avian cochlear neurons of the nucleus magnocellularis (NMC) are known to encode temporal information of sound. The neuron generated only a single action potential at a stable timing even though suprathreshold currents of long duration (> 100 ms) was injected. The threshold for the action potential was -42 mV. In voltage-clamp experiments, a TTX-sensitive Na current was activated at membrane potentials more positive than -50 mV. A low voltage activated (LVA) Ca current and a high voltage activated (HVA) Ca current were observed. The LVA Ca current was activated from -65 mV and showed a voltage dependent inactivation. The HVA Ca current was activated from -40 mV and did not show any inactivation. The LVA Ca current and the HVA Ca current were sensitive to Ni2+ (0.1 mM) and Nifedipine (10-20 mM), respectively. NMC neurons showed a TEA-sensitive K current and a 4-AP-sensitive K current. With 4-AP (0.5 mM) in a bathing medium, the threshold of action potential was decreased to -49 mV and the timing of action potential generation showed a wider distribution than that of control. Ni2+ (0.1 mM) reversed effects of 4-AP on the threshold and the variability of action potential onsets. It is concluded that a 4-AP-sensitive current counteracts the LVA Ca current that facilitates Na spike generation, and sets a threshold to a higher level for generating a single action potential at a precise timing following synaptic inputs from the auditory nerve.

Dynamic properties, interactions and adaptive modifications of vestibulo-ocular reflex and optokinetic response in mice.

Dynamic properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic response (OKR) were studied in mice. The VOR was examined in the dark (VORD), in the light (VORL) and in the condition in which most of the visual field moves synchronously with the head motion (VORF). A mouse and/or a surrounding screen with vertical stripes was rotated sinusoidally, and the gain and phase of eye movements were measured in wide dynamic stimulation ranges. The working conditions of VOR and OKR were supplementary; OKR worked at low speeds of head turn and VOR at high speeds. Examination of VORL and VORF revealed non-linear interaction of VOR and OKR. The continuous sinusoidal head oscillation coupled with the in-phase or the out-of-phase oscillation of the surrounding screen, decreased or increased the VORD gain, and increased or decreased the VORD phase lead, respectively. Continuous oscillation of the surrounding screen increased the OKR gain and decreased the phase delay. These changes of VOR and OKR work to reduce the retinal slip. The present study provides fundamental information concerning the dynamic properties of VOR and OKR and the nature of their adaptive modifications in mice, which have been extensively used in genetic manipulation recently.

Expression of cysteine proteinases and their inhibitor, cystatin beta, in cultured rat mesangial cells.

Matrix expansion in the glomerular mesangial area is observed in diabetic nephropathy. Intracellular breakdown of long-lived proteins was lower in mesangial cells in the high glucose medium than that in the control medium. Enzymatic activity of cathepsin L increased 1.4-fold after 6 h of treatment with the high glucose, and then declined gradually to 72% of control cells after treatment for 36 h. Change in the enzyme activity of cathepsin B showed a similar time course but less magnitude than that of cathepsin L. Immunoblot analysis with anti-cathepsin L antibody showed that change in the enzyme activity of cathepsin L was due to the change in the amount of cathepsin L, and that with anti-cathepsin B antibody showed no change in the amount of cathepsin B in the mesangial cells treated with high glucose. Intracellular cathepsin activities were controlled not only by the amounts but also by the inhibitor cystatin beta. Immunoblot analysis with anti-cystatin beta antibody showed that intracellular levels of cystatin beta increased slightly after 24 h of treatment with high glucose. These changes were derived from changes in mRNA level. These results, therefore, demonstrated that the decrease of intracellular protein breakdown in mesangial cells treated with high glucose medium was due to both suppression of cathepsins and increase of cystatin beta.

An (CA)n dinucleotide repeat polymorphism of the interleukin-6 (IL-6) gene is associated with metacarpal bone mineral density in hemodialysis patients.

Genetic factors may play an important role in the pathogenesis of reduced bone mineral density (BMD). IL-6 is a multifunctional cytokine and a candidate gene for regulation of bone mineral density (BMD). The relationship between a microsatellite polymorphism of the IL-6 gene and metacarpal BMD in Japanese hemodialysis patients was examined. We selected 165 patients (96 males and 69 females) with a mean age of 62.0 +/- 13.7 years (mean +/- standard deviation (SD) in this study. They were dialyzed for an average of 75.8 +/- 60.8 months (mean +/- SD). The microsatellite polymorphism in the IL-6 gene was examined. According to the number of cytosine-adenine repeats, varying from 13 to 18, 6 alleles could be distinguished. Patients were categorized based on the presence or absence of the allele with 126 bp (i.e. 14 CA repeats) (allele A, all others allele O). The frequencies of IL-6 gene genotypes in hemodialysis patients were 16.4% for OO, 52.1% for AO and 31.5% for AA. The BMD score adjusted for age and body weight (Z score) in the AA genotype group (-0.93 +/- 1.17) was significantly lower than that in the OO (-0.09 +/- 1.42, mean +/- SD, p < 0.005) or AO group (-0.48 +/- 1.15, mean +/- SD, p < 0.01). Serum intact PTH in the OO genotype group (79.3 +/- 84.6) was lower than that in the AA (120.8 +/- 113.6, mean +/- SD, p 0.10) or AO group (132.1 +/- 106.5, mean +/- SD, p < 0.05). These results suggest that polymorphism of the IL-6 gene may be a useful marker for reduced BMD.

Immunohistochemical analysis of extracellular components in the glomerular sclerosis of patients with glomerulonephritis.

Immunofluorescence and immunoperoxidase staining was carried out to determine correlations between the progression of glomerular sclerosis and changes in the amount or distribution of glomerular extracellular components, including type I, III, IV, and VI collagens, laminin and fibronectin, in patients with IgA nephropathy, membranoproliferative glomerulonephritis and rapidly progressive glomerulonephritis. Staining of type I and III collagens was not observed in glomeruli from normal individuals or patients with mild glomerulonephritis. In the advanced stages of glomerulonephritis, the staining of type IV and VI collagens, laminin and fibronectin was marked in the glomerular mesangium, and the distribution of fibronectin extended to the glomerular capillary walls in the sclerotic lesions of glomeruli. However, the staining intensity of type IV collagen, laminin and fibronectin was gradually decreased during the progression of glomerular sclerosis. On the other hand, the staining of type I and III collagens was observed focally in sclerotic or hyalinotic glomeruli and around such glomeruli in those patients. Light microscopic examination revealed that patients who showed marked staining of type I and III collagens by immunofluorescence had severe damage of Bowman's capsules. These results suggest that the hyperproduction and/or invasion of interstitial collagens, i.e., types I and III, are closely linked to the progression of glomerular sclerosis and hyalinosis in patients with various types of glomerulonephritis.

Association of the DD genotype and development of Japanese type 2 diabetic nephropathy.

We determined the insertion/deletion (I/D) polymorphism of the angiotensin-coverting enzyme (ACE) gene in a multicenter trial of ethnically homogeneous Japanese type 2 diabetes mellitus (DM) patients. All patients (n = 748) were divided into 5 groups as follows: group I (normoalbuminuric patients), group II (microalbuminuric patients), group III (overt albuminuric patients with serum creatinine (s-Cr) levels of less than 1.2 mg/dl), group IV (overt albuminuric patients with s-Cr levels of more than 1.3 mg/dl but excluding hemodialysis patients), and group V (hemodialysis patients). We selected patients with a diabetic duration of more than 15 years in the mild stage (groups I and II), but placed no limits on those in the advanced and end-stages (groups III, IV and V). The frequency of the DD genotype was slightly higher in the advanced and end stages. The frequency of the DD genotype in the mild stage differed from that in the end stage (II/ID/DD 47.8%/41.0%/11.2% vs. 37.0 %/43.3%/19.7% p = 0.07, II + ID/DD 88.8%/11.2% vs. 80.3%/19.7%, p < 0.05). D allele frequency in the mild stage also differed from that in the end stage (I/D 68.3%/31.7% vs. 58.7%/41.3%, p < 0.02). The presence of the DD genotype increased the risk of end-stage renal disease (ESRD) more than that of the other genotypes (odds ratio ID/II = 1.37, 95% CI 0.82-2.27; DD/II = 2.27, 95% CI 1.12-4.61). It appears that the DD genotype is associated with progression of Japanese type 2 diabetic nephropathy.

Computer imaging analysis of the correlation between intensities of glomerular immune-deposits and histopathology in patients with IgA nephropathy.

The relationship between the intensities of IgA, C3c, and C9 deposition in renal glomeruli and the severity of histopathologic injuries in patients with IgA nephropathy was examined using Microscope-Photometer 01K and a computer. Percentages of glomerular adhesion to Bowman's capsules, crescent formation, and glomerular sclerosis were calculated in the renal specimens. There was a significant correlation between the intensity of each C3c and C9 deposition in glomeruli and the degree of glomerular adhesion to Bowman's capsules and crescent formation in patients with IgA nephropathy. There was no significant correlation between the intensity of C3c or C9 deposition in glomeruli and the degree of glomerular sclerosis. No relationship was found between the intensity of IgA deposition in glomeruli and the degree of histopathologic injuries. The patients with negative or trace amounts of glomerular C3c deposits showed less severe glomerular injuries. Thus, the intensity of C3c and C9 deposition in glomeruli appears to be one of the critical factors responsible for the active progression of glomerular inflammatory process in patients with IgA nephropathy.

Vestibulo-ocular reflex in patients with Meniere's disease between attacks.

In Meniere's disease, spontaneous nystagmus beating toward the affected ear (ipsilateral nystagmus) is frequently observed especially during vertiginous periods. VOR against horizontal rotation was recorded in 19 patients with Meniere's disease exhibiting ispilateral beating nystagmus, and the dynamic aspect of vestibular function during vertiginous periods was examined by determining VOR gain and directional preponderance (DP). The patients sat on a rotation chair and were passively rotated at about 0.3-0.6 Hz. The maximal head velocity ranged from 80 to 120 deg/s and the duration of rotation from 20 to 30 s. In most patients exhibiting ipsilateral nystagmus, VOR gain toward the affected side was higher than that toward the intact side, indicating that the peripheral vestibular system on the affected side could still respond to head movements and that its dynamic function was increased. This asymmetry disappeared along with disappearance of ipsilateral nystagmus. During the period with contralateral nystagmus, VOR gain toward the affected side became lower than that toward the intact side. These findings indicate that alterations in the dynamic property of the peripheral vestibular system may correlate with the directional change of spontaneous nystagmus. However, the degree of VOR DP (VOR DP%) did not correlate with the slow phase velocity of spontaneous nystagmus, indicating that observation of spontaneous nystagmus alone cannot determine with precision the degree of imbalance in the dynamic aspect of vestibular function.

A new vestibulo-ocular reflex recording system designed for routine vestibular clinical use.

A new vestibulo-ocular reflex (VOR) recording system was developed, which consists of an infrared eye camera, a small velocity sensor and a frequency modulator. Using this system, the head velocity signal was frequency modulated and simultaneously recorded as a sound signal on the audio track of a Hi8 video recorder with eye images. This device enabled recording of the VOR response in routine vestibular clinical practice. The reliability and effectiveness of this system were estimated by recording and analysing the VOR response against manually controlled rotation in normal subjects (n = 22) and in patients with unilateral severe vestibular hypofunction (n = 11). VOR gain on clockwise rotation viewed from the top was defined as R gain, and counterclockwise rotation as L gain. Directional preponderance (DP%) was also calculated. VOR gain towards the diseased side was significantly lower than that towards the intact side, and also significantly lower than that of normal subjects. DP% of unilateral vestibular hypofunction cases was significantly larger than that of normal subjects. These findings indicate that this VOR recording system reliably detects severe unilateral vestibular hypofunction.

The effect of intravenous lidocaine injection on hearing thresholds.

The effect of intravenous injection of lidocaine on hearing thresholds was studied in normal subjects. Continuous and intermittent tones at 1, 4 and 8 kHz were used as stimuli and the threshold change with lidocaine injection was measured using a self-recording audiometer (Békésy audiometer). Both increases and decreases in the threshold were observed. The former occurred more frequently than the latter. In cases of a threshold increase, lidocaine injection exhibited a frequency specific effect; the higher the frequency, the more often the threshold was increased by lidocaine injection. There was no significant difference in threshold changes between continuous and intermittent tones. The present results suggest that lidocaine may act on the inner ear hair cells.

[Serum concentration of laminin in transitional cell carcinoma].

The concentration of laminin in the serum was determined for 45 patients with urinary tract transitional cell carcinoma, and the clinical significance of the findings was considered. The difference between the serum laminin concentrations in the control group and the transitional cell carcinoma patient group was not statistically significant, but the serum laminin level was highest in the transitional cell carcinoma patients with metastatic foci. In many of the patients who had metastatic foci and showed clearly progressive disease, the serum laminin concentration was found to increase with the passage of time. When the transitional cell carcinoma tissues were stained by the fluorescent antibody technique, there was little distribution of laminin in the tumor tissues, contrary to our earlier-reported findings regarding the staining of laminin in renal cell carcinoma tissues. In renal cell carcinoma patients, the serum concentration of laminin had been found to be high even when there were no metastatic foci, and consideration of this fact strongly suggests the possibility that the mechanism for laminin synthesis in urinary tract transitional cell carcinoma is different from that in renal cell carcinoma. It was surmised that the serum laminin concentration has potential for use as a diagnostic indicator of metastasis in patients with urinary tract transitional cell carcinoma.

[Serum concentration of laminin in renal cell carcinoma].

Serum concentration of laminin was measured radioimmunologically in 19 patients with renal cell carcinoma and 71 normal controls. The serum laminin levels of renal cell carcinoma patients were significantly higher than those of normal controls. After nephrectomy the elevated serum levels of laminin showed marked decreases in most of the patients without metastasis. By the immunofluorescent technique with LAM-1, a monoclonal antibody which is specific to laminin A and B chains , strong fluorescence was found in the extracellular matrix in renal cancer tissue. Taken all these facts together, renal cell carcinoma may be a laminin synthetic tumor. The average serum laminin level of the patients with a disseminated disease were significantly higher than that of the patients with a localized disease. The elevated serum level of laminin may play an important role in the process of tumor metastasis. Furthermore, our data suggest that elevated laminin levels may predict the subsequent course of a tumor condition. The monitoring of serum laminin level may be valuable for following-up of the course of renal cell carcinoma.

[Immunohistochemical analysis of extracellular components on the glomerular sclerosis in patients with glomerulonephritis and diabetic nephropathy].

Immunofluorescence and immunoperoxidase staining were carried out to determine the correlations between the progression of glomerular sclerosis and changes in the amount and distribution of glomerular extracellular components, such as Type I, III, IV, V, VI collagen, laminin (LN) and fibronectin (FN) in patients with various types of glomerulonephritis and diabetic nephropathy. Six patients with IgA nephropathy, four patients with membrano-proliferative glomerulonephritis, four patients with rapidly progressive glomerulonephritis and six patients with diabetic nephropathy were examined. The intensity and distribution of Type IV collagen, LN and FN were similar between the glomeruli from normal individuals and patients with mild stages of glomerulonephritis and diabetic nephropathy. However, staining of Type I, III or V collagen was not observed in the glomeruli from normal individuals and such patients. In more advanced stages of glomerulonephritis and diabetic nephropathy, the amounts of Types IV and VI collagen, LN and FN were increased markedly in the mesangium, and their distribution extended along the glomerular capillary walls. The intensity of Type IV collagen, LN or FN in the nodular sclerotic lesions of glomeruli was decreased significantly in patients with glomerulonephritis and diabetic nephropathy. On the other hand, staining of Types I, III and V collagen was observed focally in the sclerotic or hyalinotic glomeruli and around such glomeruli in these patients. In light microscopic examinations, the patients who had marked staining of Type I, III or V collagen by immunofluorescence showed severe damage of the basement membrane in Bowman's capsules. It is concluded that hyperproduction and/or infiltration of interstitial collagens, i.e. Types I, III and V collagen, is closely linked to the progression of glomerular sclerosis and hyalinosis in patients with various types of glomerulonephritis and diabetic nephropathy.

Immunohistochemical studies of glomerular extracellular components in repeated renal biopsies of patients with IgA nephropathy.

Immunohistochemical and light microscopic examinations were carried out to assess the correlation between the progression of glomerular lesions and changes in the intensity of glomerular extracellular components such as type IV and I collagens, laminin and fibronectin, and of IgA deposits in repeated renal biopsies of patients with IgA nephropathy. By light microscopy, the percentage of glomeruli showing glomerular mesangial expansion or sclerosis was found to be significantly higher in the second renal biopsy. Type IV collagen, laminin and fibronectin were also marked in the expanded glomerular mesangium in the second biopsy. Although these components were not observed in the global sclerotic glomeruli, type I collagen was detected in such areas of patients with IgA nephropathy. Patients who revealed high percentages of glomerular sclerosis associated with marked type IV collagen, laminin, fibronectin and/or type I collagen, had high levels of proteinuria and progressive deterioration of renal function. It is concluded that hyperproduction of the above extracellular components mainly in the glomerular mesangium is closely linked to the progression of glomerular lesions in patients with IgA nephropathy.

Increased remission of early stage membranous nephropathy on long-term treatment with corticosteroid.

Sixty-five patients with primary membranous nephropathy were examined in order to assess the effects of long-term treatment with corticosteroid. The observation period varied from 8 to 279 months (average, 95 months). The patients were treated with corticosteroid alone or with combinations of corticosteroid and immunosuppressants, nonsteroidal anti-inflammatory drugs (NSAID) and/or dipyridamole. At 6 months after treatment, only 14% of the patients had achieved complete remission. At 24 months after treatment, 46% of the patients showed complete remission. The rate of clinical remission, i.e. complete and incomplete remission, was markedly increased in stage I and II patients with membranous nephropathy by Ehrenreich and Churg's classification but not in stage III patients. The actuarial survival curve indicated that 84% of the patients were alive at 10 years after onset. These data suggest that active treatment with corticosteroid is beneficial for patients with primary membranous nephropathy.

[Comparative studies of clinicopathological findings in patients with adult and juvenile onset of IgA nephropathy].

Comparative studies of clinicopathological findings were carried out in 89 patients with adult and juvenile onset of IgA nephropathy. Among 89 patients with IgA nephropathy, there were 42 patients with juvenile onset, i.e less than 19 years old, and 47 patients with adult onset, i.e. more than 35 years old. Clinical activities of both groups were examined as follows; urinary protein, mean blood pressure renal function (PSP 15 min, Ccr) and serum IgA (s-IgA). The histology of renal tissues was also examined by light microscopy and immunofluorescence in both groups. The levels of mean blood pressure or s-IgA in patients with adult onset group were significantly higher than those in patients with juvenile onset group (p less than 0.001). The levels of Ccr in patients with adult onset group were markedly decreased. The patients with more than 1.0g/day of proteinuria and more than 110 mmHg of mean blood pressure showed severe proliferative glomerular injuries by light microscopy. It is suggested that the patients with adult onset of IgA nephropathy show severe progressive and/or exacerbating factors during the clinical course.