Effects of cilostazol on development of experimental diabetic neuropathy: functional and structural studies, and Na+ -K+ -ATPase acidity in peripheral nerve in rats with streptozotocin-induced diabetes

We studied the ability of cilostazol (CL), an antithrombotic and vasodilating agent, to prevent functional, structural and biochemical abnormalities including delayed motor nerve conduction velocity (MNCV), morphological changes in myelinated fibers, and decreased Na(+)-K(+) -ATPase activity in the peripheral nerves of rats with streptozotocin (STZ)-induced diabetes. Cilostazol treatment (30 mg/kg/day p.o.) for 10 weeks significantly prevented the delay in MNCV in the tail nerve, and morphometric analysis of the sural nerves revealed that this dose of cilostazol had a significant effect on reduction of average size of myelinated fibers. In untreated diabetic rats, cyclic AMP content and Na(+)-K(+)-ATPase activity of peripheral nerve were each significantly less than in normal control rats. Cilostazol (30 mg/kg/day) prevented reduction of Na(+)-K(+)-ATPase activity. Decrease in cyclic AMP content was completely prevented with both doses of cilostazol (30 and 10 mg/kg/day). These findings suggest that cilostazol may have beneficial effects in the treatment of diabetic neuropathy, possibly via improvement of nerve Na(+)-K(+) -ATPase activity and cyclic AMP content. Cilostazol may thus be a potent drug for the clinical treatment of diabetic neuropathy.

Response dynamics and receptive-field organization of catfish ganglion cells

Responses from catfish retinal ganglion cells were evoked by a spot or an annulus of light and were analyzed by a procedure identical to the one used previously to study catfish amacrine cells (Sakai H. M., and K.-I. Naka, 1992. Journal of Neurophysiology. 67:430-442.). In two-input white-noise experiments, a response evoked by simultaneous stimulation of the center and surround was decomposed into the components generated by the center and surround through a process of cross-correlation. The center and surround responses were also decomposed into their linear and nonlinear components so that the response dynamics of the linear and nonlinear components could be measured. We found that the concentric organization of the receptive field was determined by linear components, i.e., the first-order kernels generated by the center and surround were of opposite polarity. Both the center and surround generated second-order kernels with similar signatures, i.e., the second-order components formed a monotonic receptive field. The peak response time of the first- and second-order kernels from the surround was longer by approximately 20 ms than that of the center. Except for the DC potential present in the intracellular responses, almost identical first- and second-order kernels for the center and surround were obtained from both the intracellular response and spike discharges. Thus, information on concentric organization of a receptive field is translated into spike discharges with little loss of information. A train of spike discharges carries, simultaneously, at least four kinds of information: two linear and two nonlinear components, which originate in the receptive field center and the surround. A spike train is not a simple signaling device but is a carrier of complex and multiple signals. Victor, J. D., and R. M. Shapley (1979. Journal of General Physiology. 74:671-687.) discovered similarly that, in the cat retina, static second-order nonlinearity is encoded into spike trains. Results obtained in this study support the thesis that signals generated by the preganglionic cells are translated into spike discharges without major modification and that those signals can be recovered from the spike trains (Sakuranaga, M., Y. Ando, and K.-I. Naka. 1987. Journal of General Physiology. 90:229-259.; Korenberg, M. J., H. M. Sakai, and K.-I. Naka. 1989. Journal of Neurophysiology. 61:1110-1120.). Current injection studies have shown that such signal transmission is possible (Sakai, H. M., and K.-I. Naka, 1988a. Journal of Neurophysiology. 60:1549-1567.; 1990. Journal of Neurophysiology. 63:105-119.).

Contrast gain control in the lower vertebrate retinas

Control of contrast sensitivity was studied in two kinds of retina, that of the channel catfish and that of the kissing gourami. The former preparation is dominantly monochromatic and the latter is bichromatic. Various stimuli were used, namely a large field of light, a spot-annulus configuration and two overlapping stimuli of red and green. Recordings were made from horizontal, amacrine, and ganglion cells and the results were analyzed by means of Wiener's theory, in which the kernels are the contrast (incremental) sensitivity. Modulation responses from horizontal cells are linear, in that the waveform and amplitude of the first-order kernels are independent of the depth of modulation. In the N (sustained) amacrine and ganglion cells, contrast sensitivity was low for a large modulation input and was high for a small modulation input, providing an example of contrast gain control. In most of the cells, the contrast gain control did not affect the dynamics of the response because the waveform of the first-order kernels remained unchanged when the contrast sensitivity increased more than fivefold. The signature of the second-order kernels also remained unchanged over a wide range of modulation. The increase in the contrast sensitivity for the second-order component, as defined by the amplitude of the kernels, was much larger than for the first-order component. This observation suggests that the contrast gain control proceeded the generation of the second-order nonlinearity. An analysis of a cascade of the Wiener type shows that the control of contrast sensitivity in the proximal retinal cells could be modeled by assuming the presence of a simple (static) saturation nonlinearity. Such a nonlinearity must exist somewhere between the horizontal cells and the amacrine cells. The functional implications of the contrast gain control are as follows: (a) neurons in the proximal retina exhibit greater sensitivity to input of lower contrast; (b) saturation of a neuronal response can be prevented because of the lower sensitivity for an input with large contrast, and (c) over a large range of modulation depths, the amplitude of the response remains approximately constant.

[Gamma Glutamyltransferase]

Gamma-Glutamyltransferase (GGT), formerly called gamma-glutamyltranspeptidase, is predominantly a membrane-bound enzyme. The estimation of enzyme activity in serum is useful in monitoring hepatobiliary complaints. The electrophoresis with surfactant (Triton X-100) developed by the authors demonstrates five distinct bands of enzyme activity in the serum from patients with hepatitis. These bands are called isoenzyme GGT1 to 5 from anode to cathode, respectively. Four isoenzymes GGT2 to 5, except GGT1 are demonstrated in normal adult serum. The affinity electrophoresis is more variable to identify the hepatoma associated isoenzyme, namely HA-GGT. Concanavalin A used in the method has no affinity with HA-GGT and this isoenzyme is separated from GGT2. The diagnostic sensitivity and specificity for the measurement of HA-GGT were 58% and 83%, respectively.

Localization of matrix metalloproteinase 9 (92-kilodalton gelatinase/type IV collagenase = gelatinase B) in osteoclasts: implications for bone resorption

BACKGROUND

Matrix metalloproteinase 9 (MMP-9, 92-kD gelatinase/type IV collagenase = gelatinase B) is a member of the MMP gene family and implicated in tissue destruction in the various pathophysiologic conditions. Our previous study showed that MMP-9 purified from human fibrosarcoma cells can cleave the cross-link-containing NH(2)-terminal telopeptides of the alpha 2 chain of type I collagen and collagen types III, IV, and V as well as gelatins.

EXPERIMENTAL DESIGN

To investigate the role of MMP-9 in bone resorption we have examined its localization in the human bone tissues by immunohistochemistry and in situ hybridization. The enzymic properties were also biochemically studied.

RESULTS

Immunohistochemistry using monoclonal antibodies against MMP-1 (interstitial collagenase), MMP-2 (72-kD gelatinase/type IV collagenase = gelatinase A), MMP-3 (stromelysin-1), MMP-9, and tissue inhibitor of metalloproteinases-1 demonstrated that MMP-9 is localized exclusively in osteoclasts of the bone tissues from normal subjects and patients with rheumatoid arthritis or metastatic carcinoma whereas some osteoclasts are also labeled by anti-(MMP-1) antibody. Northern blot and in situ hybridizations of rheumatoid bone tissues using a RNA probe for MMP-9 exhibited strong signals for the mRNA within osteoclasts. MMP-9 depolymerized acid-insoluble polymers of type I collagen and digested collagen fibrils in the demineralized bone. The gelatinolytic activity of the proteinase was optimal at pH 7.5, but 50 to 80% of the full activity was retained at pH 5.5 to 6.0. It was also 90% active in the presence of 100 mM Ca2+. Degradation of acid-soluble and -insoluble type I collagens by MMP-9 was enhanced at higher concentrations of Ca2+. The zymogen of MMP-9 was activated up to approximately 85% of full activity by incubation at pH 2.3.

CONCLUSIONS

These results demonstrate that MMP-9 is produced by osteoclasts in the human bone tissues and suggest that it can degrade bone collagens in concert with MMP-1 and cysteine proteinases in the subosteoclastic microenvironment. This proteinase may play a role in the normal bone remodeling and pathologic bone resorption in the human diseases.

Nicardipine may impair glucose metabolism in hypertensive diabetic patients

The respective effects of 6 month's administration of beta-blockers (atenolol, metoprolol, carteolol and arotinolol), calcium-channel blockers (nicardipine, diltiazem) and angiotensin converting enzyme inhibitor (enalapril) on hemoglobin A1c (HbA1c) levels were evaluated in hypertensive patients with non-insulin-dependent diabetes mellitus (NIDDM), using a retrospective method. NIDDM patients with stable HbA1c and body weight were selected for this study. The following results were obtained. (1) The administration of nicardipine or beta-blockers significantly elevated HbA1c levels. (2) The administration of diltiazem or enalapril did not have any influence on HbA1c levels. These findings suggest that not only beta-blocker but nicardipine (dihydropyridine type calcium-channel blocker) may cause deterioration in glucose metabolism in NIDDM patients.

Measurements of urinary adipic acid and suberic acid using high-performance liquid chromatography

A sensitive and specific method was developed for measuring medium-chain dicarboxylic acids (adipic and suberic acid) in urine. These acids were extracted from urine with diethyl ether and converted into fluorescent derivatives with 9-anthryldiazomethane, which can be separated by high-performance liquid chromatography. The reproducibility was high and the recovery from urine was above 90%. Urinary concentrations of adipic acid in streptozotocin-induced diabetic rats were significantly higher than those in control rats. In diabetic patients, both adipic acid and suberic acid tended to be high, but not significantly. This method should be useful for measuring dicarboxylic acids in urine.

Quantitative analysis of Lewis antigens on erythrocytes by flow cytometry

We have developed a method for the quantitative analysis of Lewis antigens on human red blood cells (RBC) using immunofluorescence labeling and flow cytometry. Initially, Lewis a and Lewis b (Le(a) and Le(b)) antigens were labeled with monoclonal anti-Le(a) or anti-Le(b) antibodies followed by labeling with the fluorescein isothiocyanate (FITC)-conjugated second antibody. This method was not sensitive enough to identify the Lewis antigens on RBC, although the FITC method is very commonly used for antigens on white blood cells. Next, we selected the enhanced labeling technique using the avidin-biotin procedure. Biotinylated anti-mouse IgM was used for the second label and the reaction with R-phycoerythrin (RPE)-conjugated streptavidin followed to produce the fluorescence. The method was found to be effective for our objectives. From the results analyzed by the enhanced labeling technique, differences were not found in either the levels of the antigen-positive percentage and the peak mean channel of Le(a) antigens on RBC in the groups of blood type O and A (in ABO system). On the other hand, both the levels of Le(b) antigens on RBC were higher in the groups of blood type O than in those of blood type A. We found both Le(a) and Le(b) antigens on RBC from a few blood type O subjects. We conclude that enhanced labeling and flow cytometry constitute a useful technique for the determination of Lewis antigens on RBC and that this method enables the precise quantification of such antigens.

Significant predictors for readmission of the severely mentally ill to a provincial hospital: is the efficacy of community care explicit or implicit?

The aim of our study was to determine the factors pertaining to the seriously mentally ill patients who were forewarned of readmission to a provincial mental hospital in Vancouver, British Columbia. It is well known that, compared to the psychiatric care delivery systems in Japan, Vancouver and its metropolitan area provide the seriously mentally ill with a much wider range of community mental health programs. Our sample was 161 first admission DSM-II schizophrenic patients to a provincial hospital, who had been followed for five years. A discriminant analysis showed that of the 11 predictive factors selected, such socio-cultural factors as living situations and country of birth were the most significant predictors.

Electrochemical assay system with single-use electrode strip for measuring lactate in whole blood

We have developed an assay system for measuring lactate in whole blood, consisting of a single-use strip of an enzyme-coated electrode and a small meter. The electrode strip is made of three plastic films: a cover sheet, a spacer, and an insulation layer printed with electrodes that are coated with lactate oxidase (EC 1.1.3.x) and ferricyanide as an electron mediator. The meter measures the magnitude of the anodic current of the reduced mediator by the enzymatic reaction and displays the lactate concentration 60 s after a blood sample (5 microL) is applied. The calibration curve was linear up to 20 mmol/L, and the between-run CVs at three concentrations were 1.7-8.4%. Lactate concentrations determined by this method (y) in blood samples from healthy individuals before and after exercise agreed with the results obtained by the conventional enzymatic method (x): y = 0.97x - 0.3, Sy/x = 0.7. This assay provides a rapid and convenient test for measuring blood lactate concentrations.

Electrochemical assay system with single-use electrode strip for measuring lactate in whole blood

We have developed an assay system for measuring lactate in whole blood, consisting of a single-use strip of an enzyme-coated electrode and a small meter. The electrode strip is made of three plastic films: a cover sheet, a spacer, and an insulation layer printed with electrodes that are coated with lactate oxidase (EC 1.1.3.x) and ferricyanide as an electron mediator. The meter measures the magnitude of the anodic current of the reduced mediator by the enzymatic reaction and displays the lactate concentration 60 s after a blood sample (5 microL) is applied. The calibration curve was linear up to 20 mmol/L, and the between-run CVs at three concentrations were 1.7-8.4%. Lactate concentrations determined by this method (y) in blood samples from healthy individuals before and after exercise agreed with the results obtained by the conventional enzymatic method (x): y = 0.97x - 0.3, Sy/x = 0.7. This assay provides a rapid and convenient test for measuring blood lactate concentrations.

Communication between patients and physicians about terminal care: a survey in Japan

We assessed patient-physician communication about terminal care in Japan by examining the accuracy of physicians' estimation of their patients' preferences as regards (1) information about diagnosis and prognosis, (2) the place of death and (3) the therapeutic strategy at terminal stage (life prolongation vs pain control). We conducted a questionnaire survey on inpatients (n = 201) in three hospitals; two in rural areas (Nagano and Okinawa) and one in an urban area (Tokyo). Simultaneously we asked physicians (n = 40) in charge of the patients to estimate their attitudes. The accuracy of physicians' estimation was assessed by correct estimation rate (CER) and kappa coefficient. (1) Approximately 80% of the patients preferred to have candid information about diagnosis and prognosis, regardless of the nature of their disease. The physicians were correct in estimation only in about half of the cases. About one sixth of the physicians' guesses were in opposite direction, while about one third failed to make any estimation at all. Thus, the overall CER was 42%, 57% and 62% in Nagano, Okinawa and Tokyo respectively. (2) While 70% of the patients wished to meet their death at home, the physicians estimated this fact correctly in less than half of the cases. The physicians frequently could not make any estimation (CER: 21%, 36% and 40% respectively). (3) Two thirds of the patients preferred pain control over life prolongation. Again, CER remained in the neighborhood of 50% (CER: 49%, 49% and 64% respectively). The analysis by kappa coefficients showed that the concordance between patients' preferences and physicians' estimation was not far from a figure expected by chance alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Matrix metalloproteinase 9 (92-kDa gelatinase/type IV collagenase) from HT 1080 human fibrosarcoma cells. Purification and activation of the precursor and enzymic properties

Matrix metalloproteinase 9 (MMP-9) has been purified as an inactive zymogen of M(r) 92,000 (proMMP-9) from the culture medium of HT 1080 human fibrosarcoma cells. The NH2-terminal sequence of proMMP-9 is Ala-Pro-Arg-Gln-Arg-Gln-Ser-Thr-Leu-Val-Leu-Phe-Pro, which is identical to that of the 92-kDa type IV collagenase/gelatinase. The zymogen can be activated by 4-aminophenylmercuric acetate, yielding an intermediate form of M(r) 83,000 and an active species of M(r) 67,000, the second of which has a new NH2 terminus of Met-Arg-Thr-Pro-Arg-(Cys)-Gly-Val-Pro-Asp-Leu-Gly-Arg-Phe-Gln-Thr- Phe-Glu. Immunoblot analyses demonstrate that this activation process is achieved by sequential processing of both NH2- and COOH-terminal peptides. TIMP-1 complexed with proMMP-9 inhibits the conversion of the intermediate form to the active species of M(r) 67,000. The proenzyme is fully activated by cathepsin G, trypsin, alpha-chymotrypsin, and MMP-3 (stromelysin 1) but not by plasmin, leukocyte elastase, plasma kallikrein, thrombin, or MMP-1 (tissue collagenase). During the activation by MMP-3, proMMP-9 is converted to an active species of M(r) 64,000 that lacks both NH2- and COOH-terminal peptides. In addition, HOCl partially activates the zymogen by reacting with an intermediate species of M(r) 83,000. The enzyme degrades type I gelatin rapidly and also cleaves native collagens including alpha 2 chain of type I collagen, collagen types III, IV, and V at undenaturing temperatures. These results indicate that MMP-9 has different activation mechanisms and substrate specificity from those of MMP-2 (72-kDa gelatinase/type IV collagenase).

[Urinary trypsin inhibitor as an acute phase reactant]

Early in this century, trypsin inhibiting activity has already been recognized in patients with acute infection or renal disease. In addition to these, conditions such as coronary thrombosis, surgical operation, artificial fever by heat-killed bacilli, malignancy, leukemia, later stage of normal pregnancy, etc. have been known to cause the elevated excretion of UTI in urine. Typically, maximal excretion of UTI has been observed within one or two days after the onset. It appears that recent studies have overcome the complexity of UTI molecule. Automated measurement of urinary trypsin inhibitor (UTI) in urine sample was carried out by either enzymic or immunologic method. UTI as well as erythrocyte sedimentation rate and C-reactive protein enables us to monitor acute phase response, being confirmed in cases of abdominal surgery.

Localization of matrix metalloproteinase 3 (stromelysin) in osteoarthritic cartilage and synovium

Degradation of proteoglycans is an initial change in osteoarthritic cartilage. Matrix metalloproteinase-3 (MMP-3; stromelysin) capable of degrading cartilage proteoglycans and type IX collagen was immunolocalized in osteoarthritic and normal cartilage. Immunohistochemical studies showed MMP-3 in chondrocytes of the superficial and transition zones in approximately 90% of osteoarthritic cartilage (60 of 67 samples) and in 31% of those of the superficial zone in some normal cartilage (4 of 13 samples). MMP-3 staining correlated directly with the histological histochemical scores of Mankin and with proteoglycan depletion, up to a certain grade of severity. Chondrocytes in the deep radial zone, clusters, and osteophytes were immunostained only when proteoglycan depletion and fissures affected them. Culture media from osteoarthritic cartilage contained significantly higher levels of metalloproteinase activity that was identified as MMP-3 by immunoblotting and lower amounts of tissue inhibitor of metalloproteinases compared with those in the control samples. MMP-3 was also immunolocalized in the lining cells of most osteoarthritic synovium (20 of 23 specimens, 87%) with a direct correlation with scores of inflammatory cell infiltration in the synovium, but it was not detected in the normal synovium. Light and electron microscopic studies demonstrated that MMP-3 digests proteoglycan aggregates in human articular cartilage. Treatment of normal and osteoarthritic cartilage slices with tumor necrosis factor-alpha and/or interleukin-1 alpha increased the number of MMP-3-immunoreactive chondrocytes and the intensity of the staining. These data suggest that MMP-3 produced by the chondrocytes and synovial lining cells under stimulation with these cytokines may be important in proteoglycan degradation in human ostoearthritic cartilage.

Response dynamics and receptive-field organization of catfish amacrine cells

1. We have applied Wiener analysis to a study of response dynamics of N (sustained) and C (transient) amacrine cells. Stimuli were a spot and an annulus of light, the luminance of which was modulated by two independent white-noise signals. First- and second-order Wiener kernels were computed for each spot and annulus input. The analysis allowed us to separate a modulation response into its linear and nonlinear components, and into responses generated by a receptive-field center and its surround. 2. Organization of the receptive field of N amacrine cells consists of both linear and nonlinear components. The receptive field of linear components was center-surround concentric and opposite in polarity, whereas that of second-order nonlinear components was monotonic. 3. In NA (center-depolarizing) amacrine cells, the membrane DC potentials brought about by the mean luminance of a white-noise spot or a steady spot were depolarizations, whereas those brought about by the mean luminance of a white-noise annulus or a steady annulus were hyperpolarizations. In NB (center-hyperpolarizing) amacrine cells, this relationship was reversed. If both receptive-field center and surround were stimulated by a spot and annulus, membrane DC potentials became close to the dark level and the amplitude of modulation responses became larger. 4. The linear responses of a receptive-field center of an N amacrine cell, measured in terms of the first-order Wiener kernel, were facilitated if the surround was stimulated simultaneously. The amplitude of the kernel became larger, and its peak response time became shorter. The same facilitation occurred in the linear responses of a receptive-field surround if the center was stimulated simultaneously. 5. The second-order nonlinear responses were not usually generated in N amacrine cells if the stimulus was either a white-noise spot or a white-noise annulus alone. Significant second-order nonlinearity appeared if the other region of the receptive field was also stimulated. 6. Membrane DC potentials of C amacrine cells remained at the dark level with either a white-noise spot or a white-noise annulus. The cell responded only to modulations. 7. The major characteristics of center and surround responses of C amacrine cells could be approximated by second-order Wiener kernels of the same structure. The receptive field of second-order nonlinear components of C amacrine cells was monotonic.(ABSTRACT TRUNCATED AT 400 WORDS)

Lactate analyzer with continuous blood sampling for monitoring blood lactate during physical exercise

To monitor changes in the concentration of blood lactate during physical exercise, we used an automated lactate analyzer based on an electro-enzymatic method with continuous blood sampling through a catheter. The lactate concentration was measured every 2 min; between measurements, the instrument was calibrated with a lactate standard. Ascorbic acid, bilirubin, hemoglobin, creatinine, uric acid, and glucose did not interfere with the measurements. The lactate concentrations in blood samples from apparently healthy subjects before and after exercise correlated well (r = 0.993) with results by the conventional enzymatic method. We measured the blood lactate concentrations in nine apparently healthy volunteers during exercise on a treadmill with an increasing workload. The point at which lactate concentrations started to increase was detected easily. Thus, the lactate analyzer is suitable for monitoring changes in blood lactate concentrations during exercise.

Lactate analyzer with continuous blood sampling for monitoring blood lactate during physical exercise

To monitor changes in the concentration of blood lactate during physical exercise, we used an automated lactate analyzer based on an electro-enzymatic method with continuous blood sampling through a catheter. The lactate concentration was measured every 2 min; between measurements, the instrument was calibrated with a lactate standard. Ascorbic acid, bilirubin, hemoglobin, creatinine, uric acid, and glucose did not interfere with the measurements. The lactate concentrations in blood samples from apparently healthy subjects before and after exercise correlated well (r = 0.993) with results by the conventional enzymatic method. We measured the blood lactate concentrations in nine apparently healthy volunteers during exercise on a treadmill with an increasing workload. The point at which lactate concentrations started to increase was detected easily. Thus, the lactate analyzer is suitable for monitoring changes in blood lactate concentrations during exercise.

The messages in optic nerve fibers and their interpretation

Spike discharges are the principal carriers of information in the nervous system. Although both the ionic and the molecular mechanisms of spike generation have been studied extensively, the methods for analyzing a spike train that are currently employed have not changed much from those in use 20 years ago. There is an apparent need for a refinement of the methods used to analyze spike trains. We present here a summary of our recent results of an analysis of spike trains from retinal ganglion cells that is based on Wiener's theory of non-linear analysis or white-noise analysis. We found that spike trains carry, at least to a second-order approximation, as much information as is carried by the ganglion cell's postsynaptic potential (PSP). There is no loss of information when an analog signal, PSP, is converted into a point process, namely, spike discharges. It is indeed possible to predict the cell's PSP from a spike train. This finding has two important implications. First, the neuron network in the retina produces a PSP, the dynamics of which are optimal for triggering a spike discharge, or conversely, the spike-generation mechanism is optimized to match the dynamics of the network. The external stimulus that is optimal for production of a ganglion-cell discharge is represented as the cell's PSP. Second, there is structure encoded within the spike train; information on a second-order non-linearity is encoded by the relative timing of two consecutive spike discharges. Coding of non-linearity into a spike train is an efficient means of signal compression and is an important aspect of neurophysiology.

Sensitivity transformation for vertebrate vision

The visual response to a flash given in the dark is known to saturate according to the Michaelis-Menten relationship. Nevertheless, the incremental response from increasing levels of mean luminance tends to follow a Weber-Fechner relationship well into the saturation range determined from the Michaelis-Menten results. This sensitivity transformation from Michaelis-Menten to Weber-Fechner is an important characteristic of light adaptation in the vertebrate retina. Recent studies concerning the role of calcium in photoreceptor adaptation have shown that the relaxation from peak to plateau in the response of isolated photoreceptors was absent under conditions in which adaptation was blocked. Comparing the pronounced relaxation from peak to plateau in turtle horizontal cells with the absence of such relaxation in the catfish response, we noted also that turtle incremental sensitivity shows a Weber-Fechner relationship while catfish incremental sensitivity more closely follows the local slope of the Michaelis-Menten relation. Based on these observations, we have obtained an expression to relate the relaxation from peak to plateau with the sensitivity transformation. We assume that adaptation shifts the half-maximum point of the Michaelis-Menten curve so that the light response relaxes to a plateau value equal to a specified fraction phi of the peak response. We show that this manipulation alone results in a transformation from Michaelis-Menten kinetics to Weber-Fechner sensitivity.

Clinical significance of urinary laminin P1 in diabetic patients

The urinary concentrations of laminin fragment P1 (L-P1), a major component of laminin, were determined in diabetic patients without diabetic nephropathy and healthy controls. In the control subjects, urinary L-P1 increased with age, especially over 60 years of age. A significant increase of urinary L-P1 was observed in diabetics aged less than 50 years. Neither urinary albumin nor N-acetyl-beta-D-glucosaminidase correlated to the urinary L-P1 level. We used immunohistochemistry to locate L-P1 in the cortex of human kidneys. In non-diabetic kidneys, the glomerular and tubular basement membranes, mesangium, and Bowman's capsule were stained. In the diabetic kidney, more was stained, including the mesangial expansion and the thickened capillary basement membranes.