Inhibitory action of protein kinase Cβ inhibitor on tetrodotoxin-resistant Na+ current in small dorsal root ganglion neurons in diabetic rats

Experimental evidence has been presented to suggest that protein kinase Cbeta isoform-selective inhibitor LY333531 is effective at alleviating diabetic hyperalgesia. In the present study, we isolated small (< or =25 microm in soma diameter) dorsal root ganglion (DRG) neurons from control and streptozocin (STZ)-induced diabetic rats, and examined the acute action of LY333531 (1-1000 nM) on the tetrodotoxin-resistant Na(+) current (TTX-R I(Na)), which plays an essential role in transmitting nociceptive impulses, using the whole-cell patch-clamp method. TTX-R I(Na) in diabetic DRG neurons was enhanced in amplitude (71.5+/-3.6pA/pF, n=10 versus 41.2+/-3.3pA/pF, n=8) and was activated at more negative potentials (V(1/2), -15.1+/-1.3 mV versus -9.6+/-1.4 mV), compared with that in control neurons. Bath application of LY333531 acutely inhibited TTX-R I(Na) in both control and diabetic DRG neurons, and the degree of inhibition by the drug at concentrations of 1, 10 and 100 nM was significantly greater in diabetic DRG neurons than in control DRG neurons. Thus, TTX-R I(Na), which is upregulated in the diabetic state, is likely to be more potently inhibited by submicromolar concentrations of LY333531. These results suggest that an acute inhibition of TTX-R I(Na) by LY333531 attenuates the exaggerated excitability of DRG neurons in the diabetic state, which appears to be related at least partly to anti-hyperalgesic actions of the drug in diabetic neuropathy.

Unbalanced translocation der(1;7)(q10;p10) defines a unique clinicopathological subgroup of myeloid neoplasms

The unbalanced translocation, der(1;7)(q10;p10), is one of the characteristic cytogenetic abnormalities found in myelodysplastic syndromes (MDS) and other myeloid neoplasms. Although described frequently with very poor clinical outcome and possible relationship with monosomy 7 or 7q- (-7/7q-), this recurrent cytogenetic abnormality has not been explored fully. Here we analyzed retrospectively 77 cases with der(1;7)(q10;p10) in terms of their clinical and cytogenetic features, comparing with other 46 adult -7/7q- cases without der(1;7)(q10;p10). In contrast with other -7/7q- cases, where the abnormality tends to be found in one or more partial karyotypes, der(1;7)(q10;p10) represents the abnormality common to all the abnormal clones and usually appears as a sole chromosomal abnormality during the entire clinical courses, or if not, is accompanied only by a limited number and variety of additional abnormalities, mostly trisomy 8 and/or loss of 20q. der(1;7)(q10;p10)-positive MDS cases showed lower blast counts (P<0.0001) and higher hemoglobin concentrations (P<0.0075) at diagnosis and slower progression to acute myeloid leukemia (P=0.0043) than other -7/7q- cases. der(1;7)(q10;p10) cases showed significantly better clinical outcome than other -7/7q cases (P<0.0001). In conclusion, der(1;7)(q10;p10) defines a discrete entity among myeloid neoplasms, showing unique clinical and cytogenetic characteristics.

Effect of protein kinase C?? inhibitor on Ca2+ homeostasis in diabetic sensory neurons

To elucidate the direct effect of selective protein kinase Cbeta inhibitor LY333531 on diabetic sensory neurons, we examined intracellular Ca(2+) concentration in isolated rat dorsal root ganglion neurons using the fluorescent Ca(2+) indicator fura-2. The duration of calcium transients induced by high (50 mM) extracellular K in small diabetic dorsal root ganglion neurons was significantly prolonged compared with that in control neurons. This prolonged intracellular Ca concentration elevation in diabetic neurons was normalized rapidly and reversibly by LY333531 in a dose-dependent manner, and the effect of LY333531 was completely abolished by pretreating the neurons with mitochondrial calcium uniporter inhibitor, Ruthenium 360. These results suggest that LY333531 has an ameliorating effect on calcium homeostasis of diabetic sensory neurons via mitochondrial calcium buffering.

Cytosolic Ca2+ under high glucose with suppressed Na+/K+ pump activity in rat sensory neurons

Cytosolic Ca2+ concentration ([Ca2+]i) was measured in isolated rat dorsal root ganglion (DRG) neurons using the fluorescent Ca2+ indicator fura-2. Exposure to high (50 mM) extracellular K+ evoked a robust increase in [Ca2+]i, which was almost totally abolished by concomitant presence of nisoldipine (10 microM) and omega-conotoxin GVIA (10 microM). Whereas either high (30 mM) D-glucose alone or ouabain (100 microM) alone did not appreciably affect the high K+-induced [Ca2+]i elevation, neurons pretreated with high D-glucose together with ouabain exhibited a significantly larger [Ca2+]i response to high K+ stimulation, which was almost completely inhibited by nisoldipine and omega-conotoxin GVIA. These results suggest that a combination of high glucose and suppressed Na+/K+ pump activity potentiates the [Ca2+]i elevation stimulated by activation of the voltage-gated Ca2+ channels in rat DRG neurons.

MR angiography for the evaluation of non-systemic vasculitic neuropathy

Peripheral neuropathy due to vasculitis without any complications of vasculitis in other organs was first reported in 1987. This condition was termed non-systemic vasculitic neuropathy (NSVN). Although vasculitis is believed to develop in small arteries and arterioles in this disease, the level of vascular involvement has not been fully established. We present a case of NSVN followed up by MR angiography, which was thought to be useful to assess the level as well as the state of vascular lesions in this condition.

Properties of the Na+/K+ pump current in small neurons from adult rat dorsal root ganglia

1 The present investigation was undertaken to characterize the Na(+)/K(+) pump current in small ( Collapse

Key Words

• na⁺/k⁺ pump current
• dorsal root ganglion
• neuron
• ouabain
• α1 isoform
• α3 isoform

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MESH Headings

• Animals
• Cell Size/drug effects
• Cell Size/physiology
• Cells, Cultured
• Dose-Response Relationship, Drug
• Ganglia, Spinal/cytology
• Ganglia, Spinal/drug effects
• Ganglia, Spinal/physiology
• Male
• Membrane Potentials/drug effects
• Membrane Potentials/physiology
• Neurons/cytology
• Neurons/drug effects
• Neurons/physiology
• Ouabain/pharmacology
• Rats
• Rats, Sprague-Dawley
• Sodium-Potassium-Exchanging ATPase/physiology

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Amelioration of retarded neurite outgrowth of dorsal root ganglion neurons by overexpression of PKCdelta in diabetic rats

To examine which isoform of protein kinase C (PKC) may be associated with impaired nerve regeneration in diabetes, we compared neurite outgrowth of isolated dorsal root ganglion (DRG) neurons in streptozocin (STZ)-induced diabetic and control rats. Neurite outgrowth was significantly retarded in diabetic neurons. Rottlerin, a PKCdelta specific inhibitor, significantly retracted neurite outgrowth whereas Gö6976, an inhibitor specific for classical PKCs, had no effect, suggesting a significant role of PKCdelta in neurite outgrowth of DRG neurons. The expression of phosphorylated PKCdelta, but not total PKCdelta, in DRGs was decreased in diabetic rats. When this reduced expression was restored by overexpressing the PKCdelta in isolated DRG neurons, retardation of neurite outgrowth was significantly reversed in diabetic rats. These results suggest that a decrease in phosphorylated PKCdelta is at least in part responsible for impaired neurite outgrowth in diabetes, and that PKCdelta plays a significant role in the pathogenesis of diabetic neuropathy. This observation provides a useful clue for the treatment of diabetic neuropathy.

Diabetic neuropathy and nerve regeneration

Diabetic neuropathy is the most common peripheral neuropathy in western countries. Although every effort has been made to clarify the pathogenic mechanism of diabetic neuropathy, thereby devising its ideal therapeutic drugs, neither convinced hypotheses nor unequivocally effective drugs have been established. In view of the pathologic basis for the treatment of diabetic neuropathy, it is important to enhance nerve regeneration as well as prevent nerve degeneration. Nerve regeneration or sprouting in diabetes may occur not only in the nerve trunk but also in the dermis and around dorsal root ganglion neurons, thereby being implicated in the generation of pain sensation. Thus, inadequate nerve regeneration unequivocally contributes to the pathophysiologic mechanism of diabetic neuropathy. In this context, the research on nerve regeneration in diabetes should be more accelerated. Indeed, nerve regenerative capacity has been shown to be decreased in diabetic patients as well as in diabetic animals. Disturbed nerve regeneration in diabetes has been ascribed at least in part to all or some of decreased levels of neurotrophic factors, decreased expression of their receptors, altered cellular signal pathways and/or abnormal expression of cell adhesion molecules, although the mechanisms of their changes remain almost unclear. In addition to their steady-state changes in diabetes, nerve injury induces injury-specific changes in individual neurotrophic factors, their receptors and their intracellular signal pathways, which are closely linked with altered neuronal function, varying from neuronal survival and neurite extension/nerve regeneration to apoptosis. Although it is essential to clarify those changes for understanding the mechanism of disturbed nerve regeneration in diabetes, very few data are now available. Rationally accepted replacement therapy with neurotrophic factors has not provided any success in treating diabetic neuropathy. Aside from adverse effects of those factors, more rigorous consideration for their delivery system may be needed for any possible success. Although conventional therapeutic drugs like aldose reductase (AR) inhibitors and vasodilators have been shown to enhance nerve regeneration, their efficacy should be strictly evaluated with respect to nerve regenerative capacity. For this purpose, especially clinically, skin biopsy, by which cutaneous nerve pathology including nerve regeneration can be morphometrically evaluated, might be a safe and useful examination.

Increase in intracellular Ca(2+) and calcitonin gene-related peptide release through metabotropic P2Y receptors in rat dorsal root ganglion neurons

We examined the effects of the activation of metabotropic P2Y receptors on the intracellular Ca(2+) concentration and the release of neuropeptide calcitonin gene-related peptide (CGRP) in isolated adult rat dorsal root ganglion neurons. In small-sized dorsal root ganglion neurons (soma diameter<30 microm) loaded with fura-2, a bath application of ATP (100 microM) evoked an increase in intracellular Ca(2+) concentration, while the removal of extracellular Ca(2+) partly depressed the response to ATP, thus suggesting that the ATP-induced increase in intracellular Ca(2+) concentration is due to both the release of Ca(2+) from intracellular stores and the influx of extracellular Ca(2+). Bath application of uridine 5'-triphosphate (UTP; 100 microM) also caused an increase in intracellular Ca(2+) concentration in small-sized dorsal root ganglion neurons and the P2 receptor antagonists suramin (100 microM) and pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS; 10 microM) virtually abolished the response, indicating that the intracellular Ca(2+) elevation in response to UTP is mediated through metabotropic P2Y receptors. This intracellular Ca(2+) increase was abolished by pretreating the neurons with thapsigargin (100 nM), suggesting that the UTP-induced increase in intracellular Ca(2+) is primarily due to the release of Ca(2+) from endoplasmic reticulum Ca(2+) stores. An enzyme-linked immunosorbent assay showed that an application of UTP (100 microM) significantly stimulated the release of CGRP and that suramin (100 microM) totally abolished the response, suggesting that P2Y receptor-mediated increase in intracellular Ca(2+) is accompanied by CGRP release from dorsal root ganglion neurons. These results suggest that metabotropic P2Y receptors contribute to extracellular ATP-induced increase in intracellular Ca(2+) concentration and subsequent release of neuropeptide CGRP in rat dorsal root ganglion neurons.

Postmenopausal hormone replacement therapy use and risk of endometrial cancer in Japanese women

The relationship between the risk of endometrial cancer and the use of noncontraceptive estrogens by Japanese postmenopausal women was investigated in a hospital-based case-control study of 1025 women with endometrial cancer and 1267 with other conditions. The overall odds ratio (OR) for estrogen use with or without progestins, compared with never use of any type of estrogens, was 0.917 (95% confidence interval (CI) 0.622-1.353), suggesting that hormone replacement therapy is not a causative agent for endometrial cancer in Japanese women, and that a recent increase in the incidence of endometrial cancer in Japanese women may be related to changes in their life-style. However, although not statistically significant, women who used estrogen without progestin for 12 or more months had an OR of 2.552 (CI 0.231-28.192), while those who used estrogen with progestin for 12 or more months had an OR of 0.425 (CI 0.086-2.113). These results indicate that the addition of a progestin should be considered for reducing the risk of endometrial cancer in Japanese women.

Estrogen replacement therapy in postmenopausal women augments reactive hyperemia in the forearm by reducing angiotensin converting enzyme activity

The precise mechanism of the vasoprotective effect of estrogen replacement therapy in postmenopausal women is not fully understood. The present study sought to determine the role of nitric oxide (NO) and angiotensin-converting enzyme (ACE) in the vasodilator response of the forearm vessels induced by estrogen administration to postmenopausal women. Subjects were divided into two groups. One group received conjugated equine estrogen (0.625 mg daily) orally for 3 months (n=26), while the other received no treatment (control group, n=10). Forearm blood flow was measured by strain-gauge plethysmography. The concentrations of nitrite/nitrate (metabolites of NO), ACE activity, and lipid parameters were measured. Basal forearm blood flow, body weight, blood pressure, and heart rate were similar at baseline in both groups. After 3 months of estrogen administration, the maximal forearm blood flow response during reactive hyperemia and the serum level of nitrite/nitrate each showed a significant increase over baseline values: from 23.6+/-2.0 to 36.5+/-3.1 ml/min per 100 ml tissue (P<0.01), and from 24.8+/-2.3 to 38.6+/-3.6 micromol/l (P<0.01), respectively. Plasma levels of ACE activity were significantly reduced from baseline after 3 months of estrogen treatment (from 12.2+/-0.6 to 10.9+/-0.6 IU/l, P<0.01). No changes were seen in controls. The change in forearm blood flow after sublingual nitroglycerin was similar at baseline versus after 3 months of estrogen administration. The increase in the serum level of nitrite/nitrate after 3 months of estrogen therapy showed a significant inverse correlation (r=0.52, P<0.01) with the reduction in the plasma level of ACE activity. There was no significant correlation between the increase in serum nitrite/nitrate and any change in serum lipids, blood pressure, or other parameters. The administration of oral estrogen to postmenopausal women for 3 months increased the NO-mediated forearm endothelium-dependent vasodilatation. This was likely due, at least in part, to ACE inhibition. The latter may be one mechanism by which ERT provides its well-known cardiovascular benefit.

[Aggressive NK cell leukemia/lymphoma: an autopsy case]

A 67-year-old man was admitted with erythematous skin papules, lymphadenopathy and liver dysfunction. The bone marrow was filled with atypical lymphoid cells, and a skin biopsy showed diffuse dermal infiltration of neoplastic cells, which were positive for CD2, CD8, CD56, TIA-1, Granzyme B and EBER (ISH), but negative for CD3, CD4, CD16 and CD57. Molecular analysis showed a germline configuration for T-cell receptor beta, gamma chain genes, and monoclonal integration of Epstein-Barr virus. The THP-COP regimen was not effective and the patient died of severe metabolic acidosis 2 months later. Autopsy revealed diffuse infiltration of neoplastic cells in almost all organs. Apoptosis of tumor cells and proliferation of hemophagocytic macrophages were remarkable. Neither angiocentricity nor necrosis was observed. The findings in this patient were indistinguishable from advanced-stage nasal-type NK cell lymphoma. However, the diagnosis of aggressive NK cell leukemia/lymphoma may be justified because of the marked involvement of the marrow at onset, fulminant clinical course and diffuse infiltration of tumor cells evident at autopsy.

Leukemia blast-induced T-cell anergy demonstrated by leukemia-derived dendritic cells in acute myelogenous leukemia

OBJECTIVE

To elucidate the mechanism of immunologic escape of leukemia cells and establish an effective anti-leukemia immunotherapy, we attempted to generate dendritic cells from leukemia cells in patients with acute myelogenous leukemia (AML). Using these leukemia-derived dendritic cells, we investigated leukemia cell-associated T-cell anergy.

MATERIALS AND METHODS

Leukemia cells of 30 patients with AML were cultured with granulocyte-macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-alpha. Cultured leukemia cells were evaluated for antigen-presenting ability by mixed leukocyte culture (MLC). Normal lymphocytes, which were cocultured with leukemia blasts in the first MLC, were cultured with leukemia-derived dendritic cells in the second MLC.

RESULTS

In cultures of leukemia cells from 21 of 30 patients examined, cells with stellate morphology and cell fractions with CD1a(+) and/or CD83(+) were present. Autologous MLC using lymphocytes obtained in remission phase as responders as well as allogeneic MLC demonstrated antigen-presenting ability in leukemia-derived dendritic cells. Leukemia cells of FAB-M0, M1, M2, M3, or M6 morphology/phenotype gave rise to dendritic cells as well as leukemia cells of M5. The leukemic origin of dendritic cells was suggested by in situ hybridization. By coculture with CD80(-) leukemia blasts, the response of normal lymphocytes to leukemia-derived dendritic cells cultured from the same individual as that of leukemia blasts was markedly reduced, compared with the lymphocytes cultured with leukemia blasts from a different individual as leukemia blasts.

CONCLUSIONS

Escape of leukemia cells from anti-leukemia immunity may be associated with T-cell anergy caused by leukemia blasts. The results of the present study suggest that leukemia-derived dendritic cells can be applied efficiently in anti-leukemia immunotherapy.

Phenotype of apolipoprotein E influences the lipid metabolic response of postmenopausal women to hormone replacement therapy

OBJECTIVES

We investigated whether the phenotype of apolipoprotein E (apo E) would influence the response of postmenopausal Japanese women to hormone replacement therapy (HRT).

METHODS

We measured the plasma levels of lipoprotein and apolipoprotein in 242 postmenopausal women at baseline and again after 12 months of HRT. Patients were divided into three groups according to apo E phenotype: E2+ (E2/2 and E2/3, n=21), E3/3 (n=176), E4+ (E3/4 and E4/4, n=45).

RESULTS

We found that the E4+ group had the highest levels of total and low density lipoprotein (LDL) cholesterol and apolipoprotein B, being significantly higher than in the E2+ group at baseline. The plasma levels of total and LDL cholesterol showed a significant decrease only in the E2+ and E3/3 groups after 12 months of HRT (E2+ group, total cholesterol -8.9% and LDL cholesterol -21.5%; E3/3 group, total cholesterol -2.9% and LDL cholesterol -9.5%). No significant difference in the reduction of total and LDL cholesterol was found in the E4+ group. Other lipid parameters did not differ in the three groups.

CONCLUSIONS

These data show that the apo E phenotype influenced the response of lipid metabolism in postmenopausal women to HRT, especially in the reduction of LDL cholesterol. Therefore, apo E phenotyping may be important in predicting the cholesterol-lowering effect of HRT.

Relationship between the angiotensin-converting enzyme genotype and the forearm vasodilator response to estrogen replacement therapy in postmenopausal women

OBJECTIVES

We sought to evaluate the relationship between the angiotensin-converting enzyme (ACE) genotype and the change in forearm vasoreactivity in response to a three-month course of oral estrogen in postmenopausal women.

BACKGROUND

The ACE genotype is a known predictor of the response to an ACE inhibitor drug; however, it is not clear whether it can modify the effect of estrogen replacement therapy (ERT) on endothelial function in postmenopausal women.

METHODS

Fifty-five postmenopausal women received 0.625 mg of conjugated equine estrogen daily for three months. Forearm blood flow (FBF) was measured by strain-gauge plethysmography.

RESULTS

Twenty-one, 25 and 9 patients had the insertion/deletion (ID), II and DD genotypes, respectively. Plasma ACE activity was significantly higher at baseline in patients with either the DD or ID genotype than in those with the II genotype (p < 0.05). A significant decrease in plasma ACE activity with ERT was seen in the ID and II genotypes (p < 0.05), but not in the DD genotype. There were no significant differences in the FBF responses to reactive hyperemia at baseline between the three groups. Estrogen replacement therapy did not alter the FBF response to reactive hyperemia in the DD genotype (4.0 +/- 1.3%), although ERT significantly increased the FBF response in the ID and II genotypes (32.6 +/- 7.5% and 30.6 +/- 6.5%, respectively; p < 0.05). Forearm blood flow after administration of sublingual nitroglycerin did not change over three months in any of the three groups.

CONCLUSIONS

These findings suggest that the effect of ERT in postmenopausal women on forearm endothelial function may be determined in part by the genotype of the ACE gene.

Oral estrogen replacement therapy increases forearm reactive hyperemia accompanied by increases in serum levels of nitric oxide in postmenopausal women

The present study sought to determine the correlation between the vasodilator response of forearm resistance vessels and the circulating levels of nitric oxide (NO) after the administration of oral estrogen for 12 weeks to postmenopausal women. We classified postmenopausal women into two groups: those treated with conjugated equine estrogen (0.625 mg daily) orally for 12 weeks (n = 24) or those who received no treatment (control group, n = 8). Forearm blood flow was measured using strain-gauge plethysmography during hyperemia to evaluate endothelium-dependent vasodilation, and after sublingual nitroglycerin administration to evaluate endothelium-independent vasodilation. Serum levels of nitrite/nitrate (metabolites of NO) and lipid parameters were measured. Basal forearm blood flow, body weight and heart rate were similar in each group. After 12 weeks of estrogen administration, the maximal forearm blood flow response during reactive hyperemia and the serum level of nitrite/nitrate each showed a significant increase from 26.9 +/- 1.9 to 37.9 +/- 3.5 ml/min per 100 ml tissue (p < 0.01), and from 25.2 +/- 2.2 to 37.5 +/- 3.7 mumol/l (p < 0.05), respectively. No increases were seen in controls. The changes in forearm blood flow after sublingual nitroglycerin were similar before and after 12 weeks of estrogen administration. The increase in maximal forearm blood flow with reactive hyperemia was significantly correlated with the increase in nitrite/nitrate in the group administered estrogen (r = 0.48, p < 0.05). There was no significant correlation between maximal forearm blood flow with reactive hyperemia, nor any change in serum lipids, blood pressure or other parameters. In conclusion, the 12-week administration of oral estrogen increased forearm reactive hyperemia in postmenopausal women, probably via an increase in the production of NO.