Increased Inhibitor Activity Research Articles

Quantitative Data for Transcutaneous Electrical Nerve Stimulation and Acupuncture Effectiveness in Treatment of Fibromyalgia Syndrome.

Aim. To evaluate the effects of acupuncture and transcutaneous electric nerve stimulation (TENS) applications on the quantitative electroencephalography (qEEG) changes and to evaluate their therapeutic effects in patients with fibromyalgia syndrome (FMS). The study included 42 patients with FMS and 21 healthy volunteers. The patients were randomly assigned to two groups (n=21 in each) to undergo either TENS or acupuncture application. In both acupuncture and TENS groups, baseline electroencephalography (EEG) recording was performed for 10 min and, then, TENS or acupuncture was performed for 20 min, followed by another 10 min EEG recording. Baseline qEEG findings of FMS patients in the TENS and acupuncture groups were similar. Delta and theta powers over the frontal region of FMS patients were lower than controls. Theta powers of right posterior region were also lower than controls. In the TENS group, after the treatment, an increase was observed in the alpha power of the left anterior region as well as a decrease in pain scores. In the acupuncture group, an increase was determined in the alpha power of the right and left posterior regions as well as a decrease in pain score after the treatment. The power of low- and moderate-frequency waves on resting EEG was decreased in the patients with FMS. Decreased pain and increased inhibitor activity were found on qEEG after TENS and acupuncture applications. In conclusion, both TENS and acupuncture applications seem to be beneficial in FMS patients.

Quantitative Data for Transcutaneous Electrical Nerve Stimulation and Acupuncture Effectiveness in Treatment of Fibromyalgia Syndrome

Aim. To evaluate the effects of acupuncture and transcutaneous electric nerve stimulation (TENS) applications on the quantitative electroencephalography (qEEG) changes and to evaluate their therapeutic effects in patients with fibromyalgia syndrome (FMS). The study included 42 patients with FMS and 21 healthy volunteers. The patients were randomly assigned to two groups (n=21 in each) to undergo either TENS or acupuncture application. In both acupuncture and TENS groups, baseline electroencephalography (EEG) recording was performed for 10 min and, then, TENS or acupuncture was performed for 20 min, followed by another 10 min EEG recording. Baseline qEEG findings of FMS patients in the TENS and acupuncture groups were similar. Delta and theta powers over the frontal region of FMS patients were lower than controls. Theta powers of right posterior region were also lower than controls. In the TENS group, after the treatment, an increase was observed in the alpha power of the left anterior region as well as a decrease in pain scores. In the acupuncture group, an increase was determined in the alpha power of the right and left posterior regions as well as a decrease in pain score after the treatment. The power of low- and moderate-frequency waves on resting EEG was decreased in the patients with FMS. Decreased pain and increased inhibitor activity were found on qEEG after TENS and acupuncture applications. In conclusion, both TENS and acupuncture applications seem to be beneficial in FMS patients.

Conformational analysis of yvae peptide derivatives

Active conformations of YVAE peptide derivatives that were competitive inhibitors of 3-hydroxy3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) were determined. A type I beta-turn in N-terminuses of the studied peptides was shown to be present. The steric positioning of active conformations of peptides and statins revealed the structure-function similarity between these compounds. The results agreed with the observed increase of inhibitor activity in the studied series of peptides.

Dyslipidemia in chronic kidney disease: Causes and consequences

Cardiovascular risk increases with each decrement in renal function. Abnormalities in plasma lipoprotein composition among patients with end-stage renal disease represent a change both in lipoprotein level and structure. Low-density lipoprotein (LDL) cholesterol is not increased and LDL level is not strongly correlated with outcome. In contrast, high-density lipoprotein (HDL) levels are decreased and are inversely associated with cardiovascular risk. HDL is decreased because of an increased rate of catabolism associated with a predominance of small dense HDL. HDL fails to mature normally as a result of decreased lecithin cholesterol ester (CE) transfer protein (lecithin:cholesterol acyltransferase), leaving CE poor, triglyceride (TG) rich HDL3, and pre β HDL. Chronic kidney disease (CKD) also causes insulin resistance, and this may also contribute to low HDL levels. Plasma TG levels are increased and TGs are found in an expanded intermediate density lipoprotein (IDL) pool. These are composed of chylomicron and very low-density lipoprotein remnants resulting from delayed lipolysis on the endothelium and impaired hepatic uptake. IDL in contrast to LDL is associated with vascular disease in dialysis patients. Lipoprotein (a) (Lp (a)) levels are also increased. In patients without renal disease. The concentration of Lp (a) is inversely associated with the size of the apolipoprotein (a) isoform inherited; Lp (a) levels are increased in patients with kidney disease as a consequence of increased concentrations, primarily of the high molecular weight isoform. Lp (a) levels are also associated with cardiovascular outcome among dialysis patients.

Effect of A23187 or angiotensin II on ovarian metalloproteinase inhibitors and steroidogenesis in rats.

The present study examined the effect of the calcium ionophore A23187 or angiotensin II (AII) on the expression of ovarian metalloproteinase inhibitor and activity in rat granulosa cells and intact ovaries. Granulosa cells were collected from rats primed with pregnant mares' serum gonadotrophin (PMSG) and cultured for 24 h with A23187, AII, or the AII receptor antagonist, saralasin, in the presence or absence of LH. Metalloproteinase inhibitor activity and progesterone concentrations were determined in the media. In the A23187 experiment, addition of A23187 to granulosa cells, cultured without LH, decreased inhibitor activity, especially at the concentrations of 10 and 100 mumol l-1 (decrease to 33 +/- 7% and 31 +/- 5% of control culture values, respectively). Addition of LH to the media increased inhibitor activity 3.04 +/- 0.39 times compared with the control; however, A23187 (10 and 100 mumol l-1), in the presence of LH, decreased inhibitor activity by approximately 67%. The ionophore had disparate effects on progesterone production. Without LH, A23187 increased progesterone production by 2.96 +/- 0.47 times at 10 mumol l-1 and by 5.53 +/- 0.65 times at 100 mumol l-1. However, in LH-stimulated cells, progesterone was inhibited by A23187 at 1 and 10 mumol l-1 but was unchanged at 100 mumol l-1. In the angiotensin experiment, addition of AII (0-10,000 nmol l-1) or saralasin (1 mumol l-1) did not affect inhibitor activity or progesterone concentrations compared with control values in the absence or presence of LH. For the angiotensin experiment in vivo, PMSG-primed rats were injected with hCG followed by saralasin (10 mmol l-1) 1 or 3 h later and killed at 4, 8, or 12 h after hCG. Expression of the ovarian tissue inhibitor of metalloproteinase-1 (TIMP-1) increased by 1.7 times at 4 h, 3.3 times at 8 h, and 3.0 times at 12 h after hCG compared with values in ovaries collected at the time of hCG injection. Administration of saralasin at 1 or 3 h after hCG had no effect on expression of TIMP-1 or on serum concentrations of progesterone or oestradiol. In summary, A23187 decreased granulosa cell-derived inhibitor activity, whereas All had no effect. We propose that calcium may play a role in modulating proteolysis associated with ovulation, while AII does not appear to regulate ovarian metalloproteinase inhibitor activity.

Hormonal regulation of tissue inhibitors of metalloproteinases during follicular development in the rat ovary

Tissue inhibitors of metalloproteinases (TIMPs) are membres of a multigene family of proteinase inhibitors that regulate the activity of metalloproteinases. To test the hypothesis that TIMPs regulate connective tissue remodeling during follicular development, rats were injected with PMSG (20 IU, sc), and ovaries and serum were collected at the time of pregnant mare serum gonadotropin at the time of pregnant mare serum gonadotropin (PMSG) administration (0 h) and at 6, 12, 24, 36, and 48 h later for analysis of TIMP expression, metalloproteinase inhibitor activity, and steroidogenesis. Serum estradiol levels increased from 20.9 pg/mL at 0 h to 461 pg/mL at 48 h. Northern analysis was performed for analysis of TIMP-1, TIMP-2, and TIMP-3 expression (N = 4). For TIMP-1, PMSG stimulated a 2.4- to 2.5-fold increase in TIMP-1 mRNA at 6 and 12 h compared to ovaries collected at the time of PMSG administration (i.e., 0 h control). TIMP-1 mRNA returned to control levels within 24 h and remained unchanged through 48 h. In contrast to TIMP-1, TIMP-3 mRNA decreased by approx 2.5-fold at 6 h following PMSG administration, and expression remained decreased through 48 h. For TIMP-2, the expression of the 3.5-kb transcript decreased at 24 h after PMSG, whereas expression of the 1 kb transcript was unchanged. There was no change in metalloproteinase inhibitor activity in whole ovarian extracts between 0 and 36 h. However, there was an increase in inhibitor activity at 48 h. These findings are the first demonstration of hormonal regulation of TIMPs during the follicular phase. The differential regulation of the TIMPs by gonadotropins, for example, an increase in TIMP-1 and a concomitant decrease in TIMP-3 expression, may reflect different roles, sites of action, or enzyme specificity for the inhibitors as the follicle grows.

Regulation of granulosa cell-derived ovarian metalloproteinase inhibitor(s) by prolactin.

Increased prolactin concentrations are known to inhibit the ovarian proteolytic enzyme cascade associated with follicular rupture. It is not known whether there is also an effect of prolactin on endogenous proteinase inhibitors such as the tissue inhibitors of metalloproteinases (TIMPs). We sought to study the effect of prolactin on ovarian metalloproteinase inhibitors in cultured rat granulosa cells. Granulosa cells were cultured for 24 h with prolactin (0-1000 ng ml-1) in the absence or presence of LH. Metalloproteinase inhibitor activity in the conditioned culture media was measured by a colorimetric assay. Prolactin at 1000 ng ml-1 increased inhibitor activity by 2.86 +/- 0.63 times. Expression of mRNA encoding TIMP-1 measured by Northern analysis increased by 2.34 +/- 0.34 times with 100 ng prolactin ml-1 and by 2.43 +/- 0.42 times with 1000 ng prolactin ml-1 compared with control cultures (no LH, no prolactin). In the presence of LH, expression of mRNA encoding TIMP-1 and inhibitor activity increased by 2.60 +/- 0.6 and 4.60 +/- 0.54 times, respectively. However, no further change in mRNA expression or inhibitor activity was apparent with the addition of prolactin to LH-treated cultures. Prolactin had no effect on expression of mRNA encoding TIMP-3 in the absence or presence of LH, although LH stimulated a 1.7-fold increase in mRNA encoding TIMP-3 compared with controls. Addition of prolactin had no effect on media concentrations of oestradiol or progesterone. These data demonstrate that metalloproteinase inhibitor activity increases with increasing doses of prolactin; however, when LH was added, this effect was no longer seen. With an increase in metalloproteinase inhibitor activity, tissue metalloproteinase action could be decreased, providing a possible explanation for the local inhibition on pre- and peri-ovulatory pathways by hyperprolactinaemia.

The effects of probucol and clofibrate alone and in combination on hepatic cholesterol metabolism in the male rat.

Male rats were fed for 10 days on a diet supplemented with either probucol or clofibrate, alone or in combination, and the effects of the drugs on hepatic cholesterol metabolism studied. Plasma triacylglycerols were significantly lowered (15.6%, P < 0.05) by the drugs in combination but not individually whereas plasma cholesterol levels were reduced by probucol alone (22.4%, P < 0.05) and the combined treatment effected a further decrease leading to a total reduction of 50.6% (P < 0.001). Probucol reduced hepatic cellular triacylglycerols (20.0%, P < 0.05) and cholesterol (15.3%, P < 0.05) but cholesteryl esters were unaffected. In combination with clofibrate, probucol accentuated the reductions in both cellular cholesterol and cholesteryl esters produced by clofibrate alone and lowered their levels by 22.8%, P < 0.01 and 38.5%, P < 0.001, respectively. Although probucol, on its own, did not affect the activity of acyl-coenzyme A:cholesterol acyltransferase (ACAT), its combination with clofibrate caused less inhibition (43.5%, P < 0.01) of this enzyme activity than clofibrate alone (65.7%, P < 0.001). Probucol had a similarly moderating effect on the clofibrate-induced reductions in microsomal cholesterol and cholesteryl esters. Neither the microsomal nor the cytosolic neutral cholesteryl ester hydrolase was affected by probucol alone although both enzymes were dramatically increased (between 350% and 550%) by clofibrate and the combined treatment. The activity of the hepatic cytosolic inhibitor of cholesteryl ester hydrolase was unaffected by clofibrate or probucol individually but the two drugs in combination increased the total activity of the inhibitor by 52.1%, P < 0.01. When allowance was made for this increased inhibitor activity, it was clear that probucol accentuated the stimulatory effect of clofibrate on the cytosolic nCEH.

Inhibitor of antagonist binding to the muscarinic receptor is elevated in Alzheimer's brain

The 100,000× g supernatant fraction of human brain contains endogenous inhibitors of antagonist binding to the muscarinic receptor. Significantly greater inhibition was observed with Alzheimer's than non-demented control supernatant fractions. Low molecular weight inhibitor was separated from larger inhibitor species by membrane dialysis (3,500 dalton cut-off). The activity of low molecular weight inhibitor was greatly increased by sulfhydryl reducing agents. While the low molecular weight inhibitor was stable to heat, acid and base for short time periods (< 20 min), it was inactivated by acid hydrolysis (50% loss after 16 h, 100% loss after 96 h). The low molecular weight inhibitor activity is elevated approximately three-fold in Alzheimer's brain. The low molecular weight inhibitor from Alzheimer's brain was found to be a non-competitive inhibitor. This is the first report of endogenous inhibitors in human brain of ligand binding to the muscarinic receptor and of increased inhibitor activity in Alzheimer's disease.

Role of protein synthesis, prostaglandins, and estrogen in rat ovarian metalloproteinase inhibitor production.

Matrix metalloproteinases and their inhibitors regulate follicular connective tissue remodeling associated with ovulation. We examined the control of metalloproteinase inhibitor activity and gene expression by various treatments in cultured rat granulosa cells and intact whole ovaries. Cells were isolated from preovulatory follicles of immature eCG-primed rats and cultured with various treatments for 24 h. Metalloproteinase inhibitor activity was measured in the media. The addition of LH or the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) increased inhibitor activity 2.5- and 2.6-fold above that in control cultures, respectively. Cycloheximide treatment blocked basal and LH- and TPA-stimulated inhibitor activity, suggesting that the increase in granulosa cell inhibitor activity resulted from de novo protein synthesis. Indomethacin, a prostaglandin synthase inhibitor, had no effect on basal or LH-induced granulosa cell inhibitor activity. Addition of the antiestrogen tamoxifen citrate or an aromatase inhibitor, 10-propargylestr-4-ene-3,17-dione, did not affect basal or LH-stimulated inhibitor activity, implying that estrogen is not involved in the signal transduction pathway leading to increased inhibitor activity. Northern analysis demonstrated the presence of mRNA for a tissue-derived metalloproteinase inhibitor, TIMP-1, which increased with LH stimulation, in rat granulosa cells. Similarly, an hCG stimulus increased TIMP-1 mRNA in periovulatory ovaries to the highest levels prior to ovulation. Neither cycloheximide nor indomethacin altered hCG-stimulated TIMP mRNA levels in periovulatory ovaries. The present study demonstrates that the LH- and TPA-induced increase in inhibitor activity resulted from de novo protein synthesis; however, de novo protein synthesis does not appear necessary for the increase in TIMP mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

The Anatomical Distribution of Plasma Fibrinolytic Activity in Man During Cardiac Catheterisation

Regional circulating plasma levels of fibrinolytic activity were assessed in 15 patients undergoing cardiac catheterisation. The euglobulin clot lysis time (ECLT) was longer in the abdominal aorta (AA) than the inferior vena cava (IVC), (median difference -17.5 min, p = 0.008). This was associated with higher inhibition of plasminogen activator activity (PAI) in the AA than IVC, -1.75 IU/ml, p = 0.002. In the venous circulation the ECLT was higher in the peripheral venous sample than in the IVC, -25.5 min, p = 0.003, with higher PAI peripherally than in the IVC, -1.9 IU/ml, p = 0.001. There were no differences in ECLT, PAI, PAI-1:Ag or t-PA:Ag throughout the arterial circulation. These results demonstrate higher fibrinolytic activity with lower inhibitor activity in the venous compared to the arterial circulation. Within the venous circulation fibrinolytic activity is lower peripherally with increased inhibitor activity.

Hormonal Regulation of Matrix Metalloproteinase Inhibitors in Rat Granulosa Cells and Ovaries*

Metalloproteinases, such as collagenase or gelatinase, and their associated inhibitors appear to control connective tissue remodeling during follicular rupture. We examined the regulation of metalloproteinase inhibitor activity by various treatments in cultured rat granulosa cells. Granulosa cells were harvested from immature PMSG-primed rats and cultured with LH, the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA), cAMP, or forskolin. Inhibitor activity was measured in the medium. Increasing concentrations of either LH (0.1-1000 ng/ml) or TPA (2.5-100 nM) resulted in a dose-dependent increase in metalloproteinase inhibitor activity (2.9- and 2.4-fold increases above control, respectively). There was also a time-dependent induction of inhibitor activity in cells incubated in the presence of LH (100 ng/ml) for 6, 12, 18, or 24 h. Forskolin (0.1 mM) or cAMP (1 mM) treatment increased inhibitor activity 2.8- and 1.6-fold above that in control cultures. LH and TPA treatment in combination resulted in an additive increase in inhibitor activity compared to LH or TPA treatment alone. This finding suggested that the granulosa cell inhibitor activity might be induced through separate intracellular pathways. The inhibitor present in conditioned medium was isolated by chromatographic separation on a Sepharose 6B mol wt exclusion column. The inhibitor present was approximately 28,000 mol wt, which is consistent with the size of tissue inhibitor of metalloproteinase (TIMP). In addition to the granulosa cell experiments, changes in ovarian mRNA levels for TIMP were determined. There was a preovulatory increase in TIMP mRNA from whole rat ovaries, with the highest levels detected 12 h after hCG administration. The present study establishes that metalloproteinase inhibitor activity from rat granulosa cells is induced through separate pathways: a LH-cAMP-dependent protein kinase-A pathway and a cAMP-independent protein kinase-C pathway. Furthermore, a TIMP-like protein is observed in granulosa cell-conditioned medium, while TIMP mRNA is present in rat ovaries and increases before ovulation, suggesting that the granulosa cell metalloproteinase inhibitor is TIMP. We propose that TIMP acts in part to control the site and extent of follicular connective tissue remodeling associated with ovulation.

Tissue distribution of an endogenous inhibitor of calcium-activated neutral protease and age-related changes in its activity in rats

1. 1. The distribution of an endogenous inhibitor of calcium-activated neutral protease (CANP) and age-related changes in its activity were studied in male and female rats of different ages by a fluorometric assay on tissue extracts after heat treatment. 2. 2. Ubiquitous distribution of CANP inhibitor in brain, cardiac muscle, lung, spleen, liver, skeletal muscle, kidney and testis and its abundance in spleen, liver and kidney was demonstrated. 3. 3. Comparison in terms of units/ml of crude extracts showed that the level of CANP inhibitor exceeded that of CANP in most tissues and that the relative content of CANP inhibitor to mCANP and μCANP differed greatly among tissues. 4. 4. Sex and species differences in CANP inhibitor activity in each tissue were of little significance. 5. 5. Changes in CANP inhibitor during aging from 6 to 12 months was not obvious but senescent rats showed a tendency toward increased inhibitor activity. This increase was especially evident in the testis.

Inhibitors of Crystal Growth of Hydroxyapatite: A Constant Composition Approach

Pyrophosphate, citrate and magnesium, inhibitors of hydroxyapatite crystal growth, were studied using a seeded crystal growth system of constant composition at pH 5.80, 6.60 and 7.40. With this technique, crystal growth was studied at constant supersaturation at different pH values without the induction of other calcium phosphate phases. One inhibitor unit (that concentration of material that results in a reduction of 50 per cent in the growth rate from control) was calculated using the Langmuir adsorption isotherm. Pyrophosphate and citrate increased inhibitor activity with decreasing pH, whereas magnesium increased inhibitor activity with increasing pH. These data suggest that, at the urinary concentrations of these inhibitors, pyrophosphate is the most potent inhibitor, citrate less, and magnesium least. Pooled urine collections were studied using the same system and were found to have decreased inhibitor activity as pH decreased. This suggests that other modulators of hydroxyapatite, either promoters or inhibitors, are active in this system at the pH values studied.

Radiation Injury in Rat Lung: III. Plasminogen Activator and Fibrinolytic Inhibitor Activities

The mechanism of reduced fibrinolysis in lungs of rats whose right hemithorax had been exposed to a single dose of 25 Gy of 60Co gamma rays was determined, and fibrinolytic changes were correlated with perfusion and morphologic alterations. Reduced fibrinolytic activity in the irradiated lung was evident after 1 month, and decreased further at 2 months. From 2 to 6 months postirradiation, right lung fibrinolytic activity reached a plateau at about half of the activity in the shielded left lung or in sham-irradiated control lungs. The reduced fibrinolytic activity was largely due to decreased plasminogen activator activity, rather than to increased inhibitor activity. Changes in fibrinolytic activity of the irradiated lung closely paralleled changes in arterial perfusion. Mild ultrastructural changes in the irradiated lung (endothelial blebbing and interstitial edema) preceded fibrinolytic and perfusion defects. In contrast, marked changes such as fibrin deposition in the alveolar space and interstitial hypercellularity and fibrosis occurred after pulmonary fibrinolytic activity and perfusion were reduced.

Age-related and distributional changes in the trypsin inhibitor activity of bovine lens

Age-related changes in the bovine lens trypsin inhibitor activity were measured by assaying water soluble extracts of 10 concentric slices from the periphery to the center of the lens. Inhibitor assays were carried out at pH 7·0 and 7·9 using prenatal, calf and mature lenses. The inhibitor at pH 7·0 remained constant throughout the lens but the pH 7·9 activity decreased sharply in the lens nucleus. This was particularly true for the prenatal and calf lenses. Agarose A-15 m gel filtration of the water soluble inhibitor activity showed a decrease in inhibitor in the α-crystallin region and a corresponding increase in inhibitor activity in the HMW protein peak. Inhibitor assays were carried out on the water insoluble fractions following solubilization in 6·0 m-urea. Little or no inhibitor activity was seen in the outer cortical fractions but the inner cortex and nucleus contained high levels of inhibitor activity in the water insoluble fraction with specific activities 7- to 10-fold higher than the comparable crude lens extracts. These data suggest that the lens inhibitor activity at pH 7·0 and 7·9 aggregate into a HMW complex and with time preferentially enter the water insoluble fraction. The distribution of a purified 5·5 K inhibitor protein between the water soluble and the water insoluble fraction was measured. In the periphery all of this inhibitor was in the water soluble fraction, but toward the center of the lens this inhibitor began shifting to the water insoluble fraction. Slices taken from the lens nuclear region showed that all the inhibitor was in the water insoluble fraction as detected by both activity measurements and SDS-PAGE.

Investigations of trypsin inhibitors in leaves of four North American prairie grasses

Leaves of four important North American prairie grasses (Agropyron smithii, Andropogon gerardii, A. scoparius, and Bouteloua gracilis) were examined for the presence of trypsin inhibitors which are thought to protect some plant species from herbivory. Leaves of all four species had significant inhibitor activity at levels comparable to those in tomato leaves. Our evidence suggests that part of the inhibitor activity was proteinaceous and part may have been polyphenolic. Young leaves ofA. Smithii had more inhibitory activity than old leaves, but no leaf age differences were observed inB. gracilis. Mechanical wounding of leaves ofA. Smithii caused no consistent increase in inhibitor activity, in contrast to reports for some plant species. Plants ofA. smithii collected from areas heavily grazed by prairie dogs had trypsin inhibitor levels comparable to those in plants collected from a grazing exclosure. Thus, the ecological role of proteinase inhibitors in these Great Plains dominants remains to be demonstrated.

Differences in the behavior of SH-protease inhibitor of rat epidermis on cathepsins B and H

1. 1. SH-protease inhibitor was purified from newborn rat epidermis and its activity against cathepsins B and H compared using α-N- benzoyl- dl-arginine -2- napthylamide as a substrate. 2. 2. Preincubation of the inhibitor with the enzymes at 37°C resulted in increased inhibitor activity for cathepsin B but not for cathepsin H: pH 7.0 was more effective than the lower pH for the increase. 3. 3. The inhibition was noncompetitive regardless of the preincubation conditions and the inhibition was greater for cathepsin H than cathepsin B. 4. 4. These findings suggest that there is an SH-protease inhibitor of newborn rat epidermis which has different biological behavior against cathepsins B and H.

Activity of Excitor and Inhibitor Claw Motor Neurones During Habituation and Dishabituation of the Crayfish Defence Response

ABSTRACT The activity of the opener excitor and inhibitor motor neurones was recorded during habituation and dishabituation of the defensive claw opening response in partially restrained crayfish (Astacus sp.). Claw opening evoked by brief tactile stimulation of the thorax undergoes habituation if the stimulation is repeated at 30 s or 1 min intervals. This habituation is accompanied by a progressive decrease in evoked excitor activity, while the activity of the inhibitor remains unchanged. The habituated claw opening response can be dishabituated by tactile stimulation of the claw or head, or by visual stimulation. Dishabituation is accompanied by both an increase in evoked excitor activity and a decrease in evoked inhibitor activity. Dishabituation is also accompanied by potentiation of claw opening: that is, the same number of excitor and inhibitor spikes produce greater claw opening following dishabituating stimulation. The potentiation of claw opening following dishabituation is due in part to post-tetanic potentiation (PTP) at the excitor neuromuscular junction. PTP was demonstrated with physiological parameters of stimulation in isolated claw preparations, and is of sufficient magnitude and duration to account for the observed potentiation. These results contradict the conclusion from an earlier study (see Schone, 1961) that habituation of the claw opening response is due to an increase in inhibitor activity. They also provide new evidence for a role in dishabituation of both disinhibition and PTP.

Studies of a factor from dystrophic mouse muscle inhibitory towards protein synthesis.

A substance inhibitory to protein synthesis was purified from mouse skeletal muscle by gel filtration and ion-exchange chromatography, as well as by centrifugation on sucrose gradients. The molecular weight of the inhibitor, determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, was 71000. The inhibitory activity was insensitive to ribonuclease A, deoxyribonuclease I and phospholipase C. It was sensitive to Pronase treatment but insensitive to heat-treatment and trypsin degradation. The present results, taken together with previous studies, indicate that the site of action of the inhibitor is not on the initiation phase of protein synthesis but rather at a step after the binding of aminoacyl-tRNA to ribosomes. The increased inhibitor activity found in dystrophic muscle is discussed.