Craniospinal Irradiation for CNS Leukemia: Rates of Response and Durability of CNS Control

PURPOSE/OBJECTIVE(S)

Craniospinal irradiation (CSI) is used in the management of leukemia patients with central-nervous-system (CNS) involvement, though the data on response and local control are limited. Given the radioresponsiveness of leukemia, we hypothesized that response to CSI would be high, but CNS control would be influenced by control of systemic disease.

MATERIALS/METHODS

This retrospective, single-institution analysis included consecutive pediatric and adult patients between 2009-2021 with leukemia that underwent CSI for CNS involvement, defined as presence of blasts (i.e., >0%) on CSF flow cytometry. Endpoints included CNS response rate (RR), CNS local recurrence (LR), progression-free survival (PFS), and overall survival (OS), which were estimated from start of CSI. The probability of CNS LR was summarized using a cumulative incidence estimate, where death without LR was considered a competing risk. The probabilities of OS and PFS were obtained using Kaplan-Meier estimates.

RESULTS

Among the 39 eligible patients (43% AML, 49% ALL, 8% blast-phase CML), most were male (59%). All had CSF confirmation of disease. Median age at CSI was 31 years (range 7-67). CSI (protons 54%, photons 46%) was utilized early within the CNS disease course (median 0 CNS relapses prior to CSI). Twenty-five patients (64%) received CSI immediately prior to a stem-cell transplant (SCT), of which 21 (84%) had TBI conditioning to a median dose of 12 Gy (range 2-13.2). Patients treated with CSI alone received a higher CSI dose (median 18 Gy; range 10.8-24) than those treated with SCT consolidation (median 12 Gy; range 10.8-24). Fifteen patients had CSF-positive disease immediately prior to CSI; all 14 of those assessed for response (RR 100%) had confirmed clearance of blasts at a median of 23 days (range 7-197) from CSI start. With a median follow-up of 48 months (range 0.4-123) for survivors, 2-year PFS and OS estimates were 32% and 43%, respectively. Only 5 CNS relapses were noted (2-year CNS LR of 14%). All CNS relapses either occurred after (n = 4) or concurrently (n = 1) with a systemic relapse. In Cox regression univariate models, age, sex, time to CNS disease, positive CSF immediately prior to CSI, and SCT did not show demonstrable evidence of association with CNS LR. However, systemic relapse after CSI (HR 5.9, 95% CI 2.5-13.8, P<0.0001) and systemic disease at the time of CSI (HR 3.9, 95% CI 1.6-9.5, P = 0.003) were associated with higher risk of CNS LR. No grade-3+ acute toxicity was seen during CSI.

CONCLUSION

CSI is a well-tolerated and effective treatment option for patients with CNS leukemia. Though CNS local recurrence was modest, there was a high risk of systemic relapse and/or death. Control of systemic disease, both before and after CSI, may be important for CNS local control, and raises consideration that CNS recurrence may reflect reseeding from the systemic space.

A226 SEX-BASED DISPARITY COMPLICATIONS FOLLOWING LIVER TRANSPLANTATION

Background

Sex-based disparity exists in liver transplantation (LT) with women being disadvantaged at every stage of the process starting from assessment to post transplantation (Bryce et al., 2009). The reasons for this are multifactorial and include biological disparities, psychosocial, and allocation inequalities (Burra et al., 2013).

Aims

The purpose of this study was to identify differences in immediate or long-term complications post-LT by sex.

Methods

We analyzed 702 patients who underwent LT at the University of Alberta from 2002 to 2015. Patients aged < 18 years or requiring a repeat or multivisceral transplant were excluded. Renal dysfunction was defined according to the KDIGO criteria. Cardiovascular disease (CVD) was defined as hospitalization for or death from coronary artery disease, cardiac arrest or cerebrovascular disease.

Results

Male patients comprised 69% of the population. Time on the waitlist was similar for men (9.3 ± 11.7 months) and women (9.9 ± 12.3 months; p=0.57). Both sexes were comparable in age (males: 53 ± 10 years; females: 52 ± 11 years; p=0.19), MELD (males: 18 ± 9; females: 19 ± 10; p=0.16) and BMI (males: 27.7 ± 5.7 kg/m²; females: 27.3 ± 6.6 kg/m²; p=0.58). Women had lower creatinine pre-LT (males: 1.1 ± 0.60 mg/dL; females 0.96 ± 0.51 mg/dL; p<0.01). There were no differences in donor age, sex or BMI. Women had significantly longer hospital length of stay (males: 18 days [IQR: 11, 32]; females: 25 days [IQR: 14, 43]; p <0.001). There was no difference in risk of acute kidney injury (OR 1.4 [95% CI: 0.98, 2.1]; p=0.06), infection (OR 1.1 [95% CI: 0.8, 1.5]; p=0.52) or rejection episodes (OR 1.1 [95% CI: 0.8, 1.5]; p=0.74) following LT. Women had a higher risk of CKD post-LT (OR 2.3 [95% CI: 1.6, 3.2]; p<0.0001). There was no difference in de-novo diabetes (males: 22%; females: 16%; p=0.10), hypertension (males: 45%; females: 48%; p=0.41), dyslipidemia (males: 37%; females: 39%; p=0.67) and CVD (males: 20%; females: 19%; p=0.84) post-LT. Graft (males: 11.4 ± 0.4 years; females: 11.8 ± 0.5 years; p=0.32) and patient survival (males: 11.8 ± 0.4 years; females: 12.4 ± 0.5 years; p=0.18) were similar over a median follow up of 6.3 years [IQR: 3.5, 9.9].

Conclusions

Women spend a longer time in hospital and are at an increased risk of CKD following LT. Despite these differences, overall graft and patient survival are comparable. Our data suggest the disparity between sexes likely exists pre-LT and females that undergo LT have similar outcomes to their male counterparts.

Funding Agencies

None

A224 COVID-19 INFECTION IN LIVER TRANSPLANT RECIPIENTS: CLINICAL FEATURES, HOSPITALIZATION, AND MORTALITY FROM A CANADIAN MULTICENTRE COHORT

Background

The COVID-19 pandemic has brought significant challenges to clinicians caring for liver transplant (LT) recipients. Researchers have sought to better understand the risk and clinical outcomes of LT recipients infected with COVID-19 globally, however, there is a paucity of data from within Canada.

Aims

Our multi-center study aims to examine the characteristics and clinical outcomes of LT patients with COVID-19 in Canada.

Methods

We identified a retrospective cohort of adult LT recipients with RT-PCR confirmed COVID-19 from 7 Canadian tertiary care centers between March 2020 and June 2021. Demographic and clinical data were compiled by clinicians within those centers. We identified liver enzyme profile at the time of COVID-19 infection, immunosuppression type and post-infection adjustments, rate of hospitalization, ICU admission, mechanical ventilation, and death.

Results

A total of 49 patients with a history of LT and COVID-19 infection were identified. Twenty nine patients (59%) were male, the median time from LT was 66 months (1, 128) and the median age at COVID-19 infection was 59 years (52, 65). At COVID-19 diagnosis, the median ALT was 37 U/L (21, 41), AST U/L was 34 (20, 37), ALP U/L was 156 (88, 156), Total Bilirubin was 11 umol/L (7, 14), and INR was 1.1 (1.0, 1.1). The majority of patients (92%) were on tacrolimus monotherapy or a combination of tacrolimus and mycophenolate mofetil (MMF); median tacrolimus level at COVID-19 diagnosis was 5.3 ug/L (4.0, 8.1). Immunosuppression was modified in 8 (16%) patients post-infection; either the tacrolimus dose was reduced or MMF was held. One patient developed acute cellular rejection which recovered after re-initiation of the prior regimen. Eighteen patients (37%) required hospitalization, 6 (12%) were treated with dexamethasone, and 3 (6%) required ICU admission and mechanical ventilation. Four patients (8%) died due to complications of COVID-19. On univariate analysis, neither age, sex, co-morbidities nor duration post-transplant were associated with risk of hospitalization.

Conclusions

In our national retrospective study, approximately 40% of patients required hospitalization with a mortality rate of &lt; 10%. Previous studies have shown proximity to LT as an independent factor for mortality with COVID-19; the median time from LT for our patients was 5 years, which may explain the lower mortality rate. Of note, the median tacrolimus levels were much lower in comparison to the target of 8–10 ug/L used in the first year post-transplant. As the landscape of COVID-19 changes with vaccination, evolving treatments, and increasing rates of variant transmission, additional studies are required to continue identifying trends in clinical outcomes.

Funding Agencies

None

Erratum to "A Novel Method for Extraction of Galegine by Molecularly Imprinted Polymer (MIP) Technique Reinforced with Graphene Oxide and Its Evaluation Using Polarography"

[This corrects the article DOI: 10.1155/2020/3646712.].

A21 VITAMIN D DEFICIENCY AND ITS ASSOCIATION WITH CLINICAL OUTCOMES IN PRIMARY SCLEROSING CHOLANGITIS

Background

Primary sclerosing cholangitis (PSC) is a progressive cholestatic disease involving chronic inflammation and fibrosis of intra- and extra-hepatic ducts. Vitamin D is a secosteroid implicated in anti-inflammatory and anti-fibrotic pathways, and its deficiency has been associated with worse outcomes in chronic liver disease. Vitamin D status may also influence the course of PSC but studies evaluating this link are scarce.

Aims

To determine the association of vitamin D deficiency with the development of cirrhosis, mortality, and need for liver transplantation in patients with PSC.

Methods

Ninety-four patients with the diagnosis of PSC were evaluated and followed by the autoimmune liver disease clinic at the University of Alberta, Edmonton, Canada. Clinical data were recovered from medical charts. Vitamin D status was defined by the serum concentration of 25-hydroxyvitamin D3. Patients with levels &lt;50 nmol/L (10 ng/ml) were defined as deficient. Univariate and multivariate analyses were constructed using the Cox proportional hazards regression models. Event-free survival was defined as time from vitamin D assessment to the time of liver transplant or death.

Results

Mean age at PSC diagnosis was 32±14 years, with 67% of patients being male. The mean vitamin D level was 69±33 nmol/L (range, 4–163 nmol/L) and 26 patients (28%) had vitamin D deficiency (&lt;50 nmol/L). Among 85 patients without cirrhosis at diagnosis, 43 patients (51%) developed cirrhosis. By univariate Cox analysis, serum ALP, albumin, bilirubin and vitamin D deficiency were predictors of cirrhosis development. Vitamin D deficiency was independently associated with higher risk of developing cirrhosis (HR 2.11, 95% CI 1.002–4.44, P=0.049) after adjusting for other predictors. Median time to develop cirrhosis was shorter in patients with vitamin D deficiency (6.8 years; 95% CI, 1.7–11.8) compared to those without (10.8 years; 95% CI, 9.2 -12.4; P=0.007). Over a median follow-up period of 5.6 years, adverse outcomes (liver transplant or death) were observed in 34 patients (36%). Serum levels of albumin, ALP, bilirubin, INR, platelet count, ascites, variceal bleeding and vitamin D deficiency were associated with adverse outcomes in univariate analysis. Vitamin D deficiency was independently associated with higher risk of adverse endpoints (HR 2.87, 95% CI, 1.16–7.12, P=0.02) after adjusting for confounding factors. Event-free survival was shorter in the patients with vitamin D deficiency compared to those without deficiency (7.1 years; 95% CI, 2.4–11.9 vs. 11.4 years; 95% CI, 8.9–13.9, P=0.03, Figure 1).

Conclusions

Vitamin D deficiency was frequent in patients with PSC and was associated with higher risk of progression to cirrhosis, as well as decreased time to death and liver transplantation. The possibility of improving outcomes in PSC by vitamin D supplementation awaits further investigation.

Funding Agencies

Food and Health Innovation Initiative (Vitamin Fund), University of Alberta

Reduction in asymmetric dimethylarginine plasma levels by coenzyme Q10 supplementation in patients with type 2 diabetes mellitus

AIM

According to many studies, supplementation with Coenzyme Q10 (CoQ10) yields beneficial results in terms of endothelial function in type 2 diabetes mellitus. Despite these promising results, data elucidating the effect of CoQ10 on plasma levels of asymmetric dimethylarginine (ADMA), as a recently discussed cardiovascular risk factor, is lacking. This study was designed to investigate the effect of CoQ10 supplementation on endothelial function, specifically by evaluating plasma ADMA levels.

METHODS

Sixty-four type 2 diabetic patients were randomly assigned to two groups; either receiving 200mg/d oral dose of CoQ10 (N.=31) or receiving placebo (N.=33) for 12 weeks. Clinical and biochemical assessments were performed before and after the trial for evaluating ADMA, serum nitrite and nitrate (NOx), hemoglobin A1c and lipid profile.

RESULTS

The intervention resulted in a significant improvement in ADMA, NOx , low-density lipoprotein and hemoglobin A1c levels in CoQ10 compared to placebo group. Interestingly, difference in changes of these parameters were also significant (P=0.01, 0.03, 0.04 and 0.03, respectively).

CONCLUSION

Supplementation with CoQ10 yields beneficial effects on ADMA levels, leading to decreased diabetic cardiovascular events.

The comparative effect of pioglitazone and metformin on serum osteoprotegerin, adiponectin and intercellular adhesion molecule concentrations in patients with newly diagnosed type 2 diabetes: a randomized clinical trial

AIM

The etiologic role of inflammatory pathways in the development of diabetic complications, especially cardiovascular events, has been established. The anti-inflammatory role of metformin and pioglitazone has been described; however, no study to date has compared the efficacy of these common oral agents in this regard. In this study, the authors aimed to compare the anti-inflammatory properties of pioglitazone and metformin, with respect to their effect on serum concentrations of highly sensitive C-reactive protein (hsCRP), osteoprotegerin (OPG), intercellular adhesion molecule-1 (ICAM-1) and adiponectin.

METHODS

In an open-label randomized clinical trial, 117 patients with newly diagnosed type 2 diabetes mellitus were visited; 84 fulfilled the inclusion criteria, and were randomly allocated to 2 arms receiving either 1,000 mg/d metformin or 30 mg/d pioglitazone, respectively. Biochemical assessments were made at baseline and the end of the 3 months trial.

RESULTS

Significant reduction in FPG, insulin and HbA1c in women and men of both arms were observed. Log-hsCRP values significantly decreased in both arms. A decreasing, but non-significant trend in log-OPG levels was observed in women of the metformin arm (p=0.063). A greater reduction in log-ICAM levels was identifiable in men receiving pioglitazone compared to the other arm (p=0.008); in addition, the same trend was observed in log-OPG values (p=0.029). Nonetheless, reduction in log-ICAM and log-OPG levels was comparable between the 2 arms. A significant increase in adiponectin was observed in both men and women in the pioglitazone arm (p<0.001), whereas changes were non-significant in the metformin arm.

CONCLUSION

Remarkably, patients receiving pioglitazone revealed more significant reduction in inflammatory markers.

Electrodeposited p-type Co3O4 with high photoelectrochemical performance in aqueous medium

Electrofabricated p-Co₃O₄ based electrodes have shown efficient photoelectrochemical performance at low bias potentials in aqueous medium (∼6.5 mA cm⁻²vs. SCE at −0.3 V).

Comparative effects of metformin and pioglitazone on YKL-40 in type 2 diabetes: a randomized clinical trial

PURPOSE

Metformin and pioglitazone are believed to exert their long-term benefits by means of amelioration of chronic low-grade inflammation, a key event in development of diabetes and its long-term complications. The present trial was designed to investigate the comparative efficacy of the two anti-diabetes medications on serum concentrations of YKL-40, a novel marker of inflammation.

METHODS

In a parallel-group, open-label, randomized trial setting (ClinicalTrials.gov Identifier No. NCT01521624), 84 newly diagnosed, medication-naïve type 2 diabetes patients were assigned to metformin 1,000 mg daily (n = 42) or pioglitazone 30 mg daily (n = 42). Serum concentrations of YKL-40, along with highly sensitive C-reactive protein, indices of glycemic control and lipid profile were measured at baseline and after 3 months.

RESULTS

In the analyzed sample (metformin = 40, pioglitazone = 42), both medications were equally effective with regard to control of hyperglycemia, and hsCRP reduction (p > 0.05). However, metformin caused a significant decline in weight (p = 0.005), BMI (p = 0.004), and total cholesterol levels (p = 0.028) of the patients. Metformin also significantly reduced YKL-40 concentrations after 3 months (1.90 ± 17 vs. 1.66 ± 0.15 µg/L, p = 0.019). The amount of change in the pioglitazone arm did not reach statistical significance (2.18 ± 0.14 vs. 2.25 ± 0.16 µg/L, p = 0.687). When compared, metformin was significantly more effective than pioglitazone with respect to YKL-40 reduction in both univariate (p = 0.020, effect size = 6.7%) and multivariate models (p = 0.047, effect size = 5.7%).

CONCLUSIONS

Metformin is more effective in reduction of YKL-40 concentration in short term and the effect seems to be independent of degree of glycemic control, or hsCRP reduction.

Adrenocortical carcinoma presenting with heterosexual pseudoprecocious puberty shortly after birth: case report and review

Adrenocortical tumour is rare in children. We report on a female infant with adrenocortical carcinoma presenting with pseudoprecocious puberty at the age of two. She had a history of gradually increasing public hair growth after birth. Physical examination showed signs of virilisation such as pubic hair growth and hirsutism with evidence of facial hair growth. On biochemical evaluation, DHEA-S, 17-OH progesterone, and testosterone levels were elevated. An abdominopelvic spiral computed tomography (CT) scan with intravenous contrast identified a well-defined heterogeneously enhanced mass with areas of necrosis in the right adrenal gland and downward displacement of the underlying kidney. There was no evidence of distant metastasis on CT imaging. An exploratory laparotomy was performed in which a large, haemorrhagic and necrotic mass in the right adrenal gland with pressure effect on right liver lobe and signs of thrombosis in the inferior vena cava was detected. Pathologic examination confirmed the adrenocortical carcinoma. She received eight cycles of adjuvant chemotherapy with Carboplatin, Etoposide, and Doxorubicin regimens and underwent follow-up visits thereafter in which no sign of recurrence was observed. In conclusion, adrenocortical carcinomas are rare in children, but they should be considered in any child presenting with signs of pseudoprecocious puberty.

The synthesis and subcellular distribution of pyridoxal phosphate in rat and bovine retinas

In the absence of any known studies dealing with status of vitamin B(6) metabolism in mammalian retinas, the concentration of pyridoxal phosphate and the activity of its synthesizing enzyme pyridoxal kinase were determined in rat retina and bovine retina and its subcellular compartments. In bovine retina, the highest concentration of pyridoxal phosphate (148 pmol/mg protein) was present in pellet 2 fraction containing synaptosomes comparable to those isolated from brain. The second highest concentration of pyridoxal phosphate (91 pmol/mg protein) was present in pellet 1 fraction containing large synaptosomes resembling photoreceptor cell terminals. The concentrations of pyridoxal phosphate in pellets 1 and 2 fractions were approx 3- to 6-fold higher than that found in the whole retina. The concentration of pyridoxal phosphate and the activity of pyridoxal kinase in the rat retina were considerably higher than those observed in the bovine retina. In general, no apparent correlation existed between the concentrations of pyridoxal phosphate and the activities of pyridoxal kinase in bovine retina and its subcellular compartments.

Prevalence of HCV and HGV infections in Iranian liver transplant recipients

BACKGROUND

Infections with hepatitis C virus (HCV) and the familially related hepatitis G virus (HGV) threaten survival of liver transplant recipients. The prevalence and pathogenic effects of these hepatitis virus infections, in particular HGV, on clinical outcome and the need for surveillance are controversial. The present study examined the prevalence of HCV and HGV infections using polymerase chain reaction-based molecular methods in Iranian patients who had undergone orthotopic liver transplantation (oLT).

MATERIALS AND METHODS

Between 2007 and 2010, 202 EDTA-treated blood samples were obtained before and after liver transplantation in 106 patients. An optimized qualitative in-house multiplex reverse transcription polymerase chain reaction protocol was used for simultaneous diagnosis of HCV and HGV infections.

RESULTS

Hepatitis C virus molecular infection was diagnosed in 13 of 202 plasma samples (6.4%) in 10 of 106 patients (9.4%) before and after oLT. Eleven of 202 plasma samples (5.4%) from 10 of 106 patients (9.4%) demonstrated HGV genome infection before and after oLT.

CONCLUSION

Detection of moderate prevalence of HCV and especially HGV infection in liver transplant recipients suggests potential importance of HCV infection in liver dysfunction and supports the hypothesis that HGV infection has a pathogenic role in liver-related clinical complications.

Growth and production optimization of tropane alkaloids in Datura stramonium cell suspension culture

Abstract: A number of physicochemical conditions such different concentration of glucose, sucrose, potassium nitrate, ammonium nitrate, calcium chloride and temperatures were tested to optimize growth and production of tropane alkaloids from Datura stramonium (Solanaceae) plants. Cell suspension from semi-clear calli of leave explants developed in MS medium containing kinetin (0.5 mg L(-1)) and NAA (2 mg L(-1)) hormones was used to measure biomass and total alkaloids and comparison of treatments. The results showed that 30 and 40 g L(-1) glucose led to the highest level of alkaloids and biomass productions, respectively. 20 and 40 g L(-1) sucrose concentrations resulted in order the most rates of alkaloids and biomass productions. The results showed that increasing of nitrate concentration led to the reduction of the alkaloids. The best concentration of potassium nitrate for the production of tropane alkaloids and biomass were in order 9.4 and 3.76 mM. Also it was evinced that the optimized concentration of ammonium nitrate for alkaloids production was 10.3 mM and for the biomass was 41.22 mM. The best concentration of calcium chloride for growth and production of the alkaloids was 7.92 mM. Testing different temperature specified that the best condition for production of the alkaloids was 20 degrees C whereas it was 25 degrees C for biomass production. The results of this study could be recommended to farmers involved in production of D. stramonium for tropain alkaloids at industrial and semi-industrial scales.

Coenzyme Q10 inhibits mitochondrial complex-1 down-regulation and nuclear factor-kappa B activation

We have used control-homozygous weaver mutant, and -heterozygous weaver mutant mice in order to explore the basic molecular mechanism of neurodegeneration and the neuroprotective potential of coenzyme Q(10). Homozygous weaver mutant mice exhibited progressive neurodegeneration in the hippocampus, striatum, and cerebellum, and a reduction in the striatal levels of dopamine and coenzyme Qs (Q(9) and Q(10)) without any significant changes in norepinephrine and serotonin. Mitochondrial complex-1 was down regulated; whereas nuclear factor-kappa B was up regulated in homozygous weaver mutant mice. Rotenone inhibited complex-1, enhanced nuclear factor-kappa B, and caused apoptosis in human dopaminergic (SK-N-SH) neurons; whereas nuclear factor-kappa B antibody suppressed rotenone-induced apoptosis, suggesting that enhancing coenzyme Q(10) synthesis and suppressing the induction of NF-kappa B, may provide neuroprotection.

Identification of dopamine transporter in bovine pineal gland using [3H]GBR 12935

The mammalian pineal gland contains several neurotransmitters and receptors for amino acids, biogenic amines, and peptides. Some of these, such as D1 and D2 dopamine receptors, have been previously identified and characterized in the bovine pineal gland by our group. As a matter of fact, the density of D1 dopamine receptors in the pineal gland is higher than that of corpus striatum, suggesting that this organ must possess a high affinity dopamine transporter, which has been identified in this study by using [3H]GBR 12935 as a radiological ligand and nomifensine to determine non-specific binding. The association rate of [3H]GBR 12935 binding to the pineal membrane was examined as a function of time. The binding reached equilibrium within 45 min of incubation at 25 degrees C. The specific binding was reversible and saturable. The dissociation time course of the specific [3H]GBR 12935 binding from the bovine pineal membrane was also studied. A half-life (t1/2) of 14-min was obtained. The saturation analysis of the [3H]GBR 12935 binding revealed a dissociation equilibrium constant (Kd) of 6.0 +/- 0.9 nm and a receptor density (Bmax) of 6.9 +/- 0.3 pmol/mg protein, which were comparable with those values obtained from bovine striatum and frontal cortex. In competitive experiments, the concentrations of drugs required to inhibit 50% of the binding (IC50) were in descending order GBR 12909 > GBR 12935 > trans-flupenthixol > nomifensine > cis-flupenthixol > amitriptyline > imipramine > desipramine > dopamine > fluoxetine > fuvoxamine > d-amphetamine. However, nisoxetine, SCH 23390, norepinephrine, and serotonin were unable to displace [3H]GBR binding. These results show that drugs capable of blocking dopamine transporters were effective in displacing [3H]GBR binding; whereas specific norepinephrine and serotonin transporter inhibitors were less effective or ineffective. In addition, the dopamine transporter is ion-dependent as sodium increased [3H]GBR binding in a concentration related manner. These results indicate that a high affinity dopamine transporter exists in the bovine pineal, which may exhibit circadian periodicity, and whose physiological functions need to be delineated and characterized in future investigations.

Insulin-like growth factor I (IGF-1) supplementation prevents diabetes-induced alterations in coenzymes Q9 and Q10

Diabetes, which causes enhanced oxidative stress, is a multifactorial disease that leads to deleterious effects in many organ systems within the body. Ubiquinones (coenzyme Q(9) and Q(10)) are amphipathic molecular components of the electron transport chain that function also as endogenous antioxidants and attenuate the diabetes-induced decreases in antioxidant defense mechanisms. Insulin-like growth factor 1 (IGF-1) is considered to be an "essential surviving factor", the level and function of which are compromised in diabetes. This study investigated the impact of IGF-1 supplementation on ubiquinone levels in a rat model of type I diabetes. Adult male Sprague-Dawley rats were divided into four groups: control, control plus IGF-1, diabetic and diabetic plus IGF-1. Diabetic animals received a single intravenous injection of streptozotocin (STZ, 55 mg/kg). IGF-1 supplementation groups received a daily intraperitoneal dose of 3 mg IGF-1 per kilogram body weight for 7 weeks. Coenzyme Q(9) and Q(10) levels were assessed by ultraviolet detection on high pressure liquid chromatography. STZ caused a significant reduction in body weight and an elevation in blood glucose level, which were not prevented by IGF-1 supplementation. In addition Q(9) and Q(10) levels in diabetic liver were significantly elevated. IGF-1 supplementation prevented liver alterations in Q(10) but not Q(9) levels. Q(9) and Q(10) levels in diabetic kidney were significantly depressed, and these deleterious effects were abolished by IGF-1 treatment. These data suggest that IGF-1 antagonizes the diabetes-induced alterations in endogenous antioxidants including coenzyme Q(10), and hence may have a therapeutic role in diabetes.

Deferoxamine attenuates iron-induced oxidative stress and prevents mitochondrial aggregation and alpha-synuclein translocation in SK-N-SH cells in culture

One of the defining characteristics of neurodegenerative diseases, including Parkinson's disease, is an abnormal accumulation of iron in the affected brain areas. By using SK-N-SH, a dopaminergic cell line, we have found that iron (100-250 microM FeSO(4)) decreased cell viability, increased lipid peroxidation, and the said effects were blocked by deferoxamine (DFO: 10 microM). Furthermore, DFO, in the absence of iron, enhanced the level of adenosine triphosphate (ATP), but caused chromatin condensation and cell death. Morphological studies revealed that iron (50-100 microM) altered mitochondrial morphology, disrupted nuclear membrane, and translocated alpha-synuclein from perinuclear region into the disrupted nucleus. The results of these studies suggest that DFO is able to block and attenuate iron-mediated oxidative stress. However, in the absence of excess iron, DFO itself may have deleterious effects on the morphology and hence integrity of dopaminergic neurons.

Distribution of coenzyme Q homologues in brain

Ubiquinone (coenzyme Q10), in addition to its function as an electron and proton carrier in mitochondrial electron transport coupled to ATP synthesis, acts in its reduced form (ubiquinol) as an antioxidant, inhibiting lipid peroxidation in biological membranes and protecting mitochondrial inner-membrane proteins and DNA against oxidative damage accompanying lipid peroxidation. Tissue ubiquinone levels are subject to regulation by physiological factors that are related to the oxidative activity of the organism: they increase under the influence of oxidative stress, e.g. physical exercise, cold adaptation, thyroid hormone treatment, and decrease during aging. In the present study, coenzyme Q homologues were separated and quantified in the brains of mice, rats, rabbits, and chickens using high-performance liquid chromatography. In addition, the coenzyme Q homologues were measured in cells such as NG-108, PC-12, rat fetal brain cells and human SHSY-5Y and monocytes. In general, Q1 content was the lowest among the coenzyme homologues quantified in the brain. Q9 was not detectable in the brains of chickens and rabbits, but was present in the brains of rats and mice. Q9 was also not detected in human cell lines SHSY-5Y and monocytes. Q10 was detected in the brains of mice, rats, rabbits, and chickens and in cell lines. Since both coenzyme Q and vitamin E are antioxidants, and coenzyme Q recycles vitamins E and C, vitamin E was also quantified in mice brain using HPLC-electrochemical detector (ECD). The quantity of vitamin E was lowest in the substantia nigra compared with the other brain regions. This finding is crucial in elucidating ubiquinone function in bioenergetics; in preventing free radical generation, lipid peroxidation, and apoptosis in the brain; and as a potential compound in treating various neurodegenerative disorders.

Neuroprotective actions of selegiline

Selegiline, a selective inhibitor of monoamine oxidase-B (MAO-B), was one of the first adjunct therapies in clinical neurology. A retrospective analysis of data from patients with Parkinson's disease found a significant increase in survival in those treated with selegiline plus L-dopa compared with L-dopa alone. The mechanism of action of selegiline is complex and cannot be explained solely by its MAO-B inhibitory action. Pretreatment with selegiline can protect neurons against a variety of neurotoxins, such as 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP), 6-hydroxydopamine, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), methyl-beta-acetoxyethyl-2-chloroethylamine (AF64A), and 5,6-dihydroxyserotonin, which damage dopaminergic, adrenergic, cholinergic, and sertoninergic neurons, respectively. Selegiline produces an amphetamine-like effect, enhances the release of dopamine, and blocks the reuptake of dopamine. It stimulates gene expression of L-aromatic amino acid decarboxylase, increases striatal phenylethylamine levels, and activates dopamine receptors. Selegiline reduces the production of oxidative radicals, up-regulates superoxide dismutase and catalase, and suppresses nonenzymatic and iron-catalyzed autooxidation of dopamine. Selegiline compensates for loss of target-derived trophic support, delays apoptosis in serum-deprived cells, and blocks apoptosis-related fall in the mitochondrial membrane potential. Most of the aforementioned properties occur independently of selegiline's efficacy to inhibit MAO-B.

Ubiquinone (Coenzyme Q10) and Mitochondria in Oxidative Stress of Parkinson’s Disease

Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease affecting approximately1% of the population older than 50 years. There is a worldwide increase in disease prevalence due to the increasing age of human populations. A definitive neuropathological diagnosis of Parkinson's disease requires loss of dopaminergic neurons in the substantia nigra and related brain stem nuclei, and the presence of Lewy bodies in remaining nerve cells. The contribution of genetic factors to the pathogenesis of Parkinson's disease is increasingly being recognized. A point mutation which is sufficient to cause a rare autosomal dominant form of the disorder has been recently identified in the alpha-synuclein gene on chromosome 4 in the much more common sporadic, or 'idiopathic' form of Parkinson's disease, and a defect of complex I of the mitochondrial respiratory chain was confirmed at the biochemical level. Disease specificity of this defect has been demonstrated for the parkinsonian substantia nigra. These findings and the observation that the neurotoxin 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP), which causes a Parkinson-like syndrome in humans, acts via inhibition of complex I have triggered research interest in the mitochondrial genetics of Parkinson's disease. Oxidative phosphorylation consists of five protein-lipid enzyme complexes located in the mitochondrial inner membrane that contain flavins (FMN, FAD), quinoid compounds (coenzyme Q10, CoQ10) and transition metal compounds (iron-sulfur clusters, hemes, protein-bound copper). These enzymes are designated complex I (NADH:ubiquinone oxidoreductase, EC 1.6. 5.3), complex II (succinate:ubiquinone oxidoreductase, EC 1.3.5.1), complex III (ubiquinol:ferrocytochrome c oxidoreductase, EC 1.10.2.2), complex IV (ferrocytochrome c:oxygen oxidoreductase or cytochrome c oxidase, EC 1.9.3.1), and complex V (ATP synthase, EC 3.6.1.34). A defect in mitochondrial oxidative phosphorylation, in terms of a reduction in the activity of NADH CoQ reductase (complex I) has been reported in the striatum of patients with Parkinson's disease. The reduction in the activity of complex I is found in the substantia nigra, but not in other areas of the brain, such as globus pallidus or cerebral cortex. Therefore, the specificity of mitochondrial impairment may play a role in the degeneration of nigrostriatal dopaminergic neurons. This view is supported by the fact that MPTP generating 1-methyl-4-phenylpyridine (MPP(+)) destroys dopaminergic neurons in the substantia nigra. Although the serum levels of CoQ10 is normal in patients with Parkinson's disease, CoQ10 is able to attenuate the MPTP-induced loss of striatal dopaminergic neurons.

Salivary melatonin response to acute pain stimuli

Evidence for a relationship between melatonin, nociception, and analgesia in humans is based on data that are only linked by association and simultaneous occurrence. Studies have reported inverse correlation of the circadian melatonin rhythm with nociception latency and enhancement of opioid analgesia by simultaneous administration of melatonin in animals. This study examines the response of salivary melatonin to acute pain stimuli in 18 healthy subjects ranging in age from 19 to 50 years. A biphasic melatonin response following an acute pain stimulus of 36 V was observed, F(8, 8) = 17.839, P < 0.001. Within 5 min of the stimulus, melatonin decreased and reached a plateau of 36 pg/mL below baseline by 20 min. This decrease was followed by an increase of 5 pg/mL. Melatonin levels subsequently decreased until they had reached levels similar to those anticipated for the time of day and did not vary thereafter. The magnitude of the melatonin response was not related to age or gender. There was no association between voltage and magnitude of the melatonin responses observed at 15 min (r =0.185, P=0.51) or at 30 min (r = 0.468, P = 0.09). This study provides the first evidence of melatonin utilization and subsequent pineal gland synthesis following acute pain episodes in humans.

SKF-38393, a dopamine receptor agonist, attenuates 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity

Parkinson's disease (PD) is characterized by progressive degeneration of nigrostriatal dopaminergic neurons. Several factors such as inhibition of the mitochondrial respiration, generation of hydroxyl radicals and reduced free radical defense mechanisms causing oxidative stress, have been postulated to contribute to the degeneration of dopaminergic neurons. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treated animals is a useful experimental model of PD, exhibiting most of the clinical features, as well as the main biochemical and pathologic symptoms of the disease. In the present study, we have examined a dopaminergic (D1) receptor agonist, SKF-38393 HCl (SKF) for its possible neuroprotective action against MPTP-induced insults on dopaminergic neurons. MPTP is converted by monoamine oxidase-B (MAO-B) to its neurotoxic metabolite 1-methyl-4-phenyl-pyridinium (MPP+), which is then taken up into the dopaminergic neurons. SKF-38393 had no effects either on total or monoamine oxidase B in the striatum. SKF-38393 blocked the MPTP-induced depletion of glutathione and attenuated MPTP-induced depletion of dopamine. Furthermore, it enhanced the activity of superoxide dismutase and hence mimicked the action of selegiline. The results of these studies are interpreted to suggest that SKF-38393 may prove a valuable drug in the treatment of Parkinson's disease.

Introduction. Oxidative stress in mitochondria disorders of aging

These special issues of Biological Signals and Receptors are intended to describe mitochondrial DNA damage, oxidative stress and human diseases, including neurodegenerative and neuromuscular diseases, disorders associated with aging, and ischemia-perfusion injury. Traditionally, mitochondria have been viewed as the 'powerhouse' of the cell, i.e., the site of the oxidative phosphorylation machinery involved in adenosine triphosphate (ATP) production. Consequently, much of the research conducted on mitochondria over the past 4 decades has focused on elucidating both those molecular events involved in ATP synthesis by oxidative phosphorylation and those involved in the biogenesis of the oxidative phosphorylation machinery. While monumental achievements have been made, and continue to be made, in the study of these remarkable but extremely complex processes essential for the life of most animal cells, it has been only in recent years that a large body of biological and biomedical scientists have come to recognize that mitochondria participate in other important processes. Two of these are cell death and aging which, not surprisingly, are related processes both involving, in part, the oxidative phosphorylation machinery. This new awareness has sparked a new and growing area of mitochondrial research that has become of great interest to a wide variety of scientists ranging from those involved in elucidating the role of mitochondria in cell death and aging to those interested in either suppressing or facilitating these processes as it relates to identifying new therapies or drugs for human disease.

Free radical scavenging actions of hippocampal metallothionein isoforms and of antimetallothioneins: an electron spin resonance spectroscopic study

The high concentration of zinc in the hippocampal mossy fiber axon boutons is localized in the vesicles and is mobilized by exocytosis of the zinc-laden vesicles. Furthermore, the mammalian hippocampi contain metallothionein (MT) isoforms which regulate the steady state concentration of zinc, an important antioxidant. Indeed, zinc deprivation leads to an increased lipid peroxidation, reduces the activity of Cu++-Zn++ superoxide dismutase, and protect against oxidative stress such as exposure to ultraviolet A irradiation. By employing electron spin resonance (ESR) spectroscopy, we have demonstrated that rat hippocampal MT isoforms 1 and 2 were able to scavenge 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), hydroxyl radicals (*OH) generated in a Fenton reaction, and superoxide anions (O2*-) generated by the hypoxanthine and xanthine oxidase system. In addition, MT-1 isoform protected the isolated hepatocytes from lipid peroxidation as determined by thiobarbituric acid bound malondialdehyde. MT antibodies scavenged DPPH radicals, hydroxyl radicals and reactive oxygen species but not superoxide anions. The results of these studies suggest that although both isoforms of MT are able to scavenge free radicals, the MT-1 appears to be a superior scavenger of superoxide anions and 1,1-diphenyl-2-picrylhydrazyl radicals. Moreover, antibodies formed against MT isoform retain some, but not all, free radical scavenging actions exhibited by MT-1 and MT-2.

MPTP decreases MT-I mRNA in mouse striatum

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a drug that induces parkinsonism in humans and non-human primates. Free radicals are thought to be involved in its mechanism of action. Recently, metallothionein has been proposed to play a role as a scavenger of free radicals. In the present work, we studied the effect of MPTP neurotoxicity on brain metallothionein-I (MT-I) mRNA expression. Male C-57 black mice were treated with MPTP (30 mg/kg, i.p., daily) for 3 or 5 days. All animals were killed by cervical dislocation 7 days after the last MPTP dose. The brains were removed quickly and immediately frozen, and quantitative in situ hybridization was performed using MT-I cDNA probe. MT-I mRNA content in striatum, a region which is known to be highly predisposed and sensitive to MPTP-induced oxidative stress, decreased by 30% (3 days) and 39% (5 days) respectively, after the last MPTP administration. These results suggest that MT-I gene expression is decreased in MPTP neurotoxicity. It is suggested that the reduction of MT, an anti-oxidant and a free radical scavenger, in the striatum by MPTP enables the neurotoxin to exert maximal oxidative damage to the striatum.

Changes of metallothionein I + II proteins in the brain after 1-methyl-4-phenylpyridinium administration in mice

1-methyl-4-phenylpyridinium (MPP+) is a drug that induces a Parkinson's-like syndrome in several species. Oxidative stress resulting from either excess generation or reduced scavenging of free radicals has been proposed to play a role in its neurotoxicity. It has been suggested that metallothionein (MT) protects against oxidative damage of the central nervous system produced by overproduction of free radicals. This study examined the effect of MPP+ on metallothionein I+II protein content in different brain regions. NIH mice were injected with MPP+ (4.5, 9.0 or 18 microg/3 microl) into their right lateral ventricle. Corpus striatum, cerebellum, midbrain, frontal cortex and hippocampus were dissected out and their metallothionein concentrations were analyzed by radioimmunoassay. MPP+ reduced the concentration of MT I+II proteins (38%) only in the striatum. The results suggest that changes in MT I+II content may be associated with MPP+ neurotoxicity.

Free radical scavenging actions of metallothionein isoforms I and II

By employing electron spin resonance spectroscopy, we examined the free radicals scavenging effects of hepatic metallothionein (MT) isoforms I and II (MTs-I and II) on four types of free radicals. Solutions of 0.15 mM of MT-I and 0.3 mM of MT-II were found to scavenge the 1,1-diphenyl-2-picrylhydrazyl radicals (1.30 x 10(15) spins/ml) completely. In addition, both isoforms exhibited total scavenging action against the hydroxyl radicals (1.75 x 10(15) spins/ml) generated in a Fenton reaction. Similarly, 0.3 mM of MT-I scavenged almost 90% of the superoxide (2.22 x 10(15) spins/ml) generated by the hypoxanthine and xanthine oxidase system, while a 0.3 mM MT-II solution could only scavenge 40% of it. By using 2,2,6,6-tetramethyl-4-piperidone as a "spin-trap" for the reactive oxygen species (containing singlet oxygen, superoxide and hydroxyl radicals) generated by photosensitized oxidation of riboflavin and measuring the relative signal intensities of the resulting stable nitroxide adduct, 2,2,6,6-tetramethyl-4-piperidine-1-oxyl, we observed that MT-II (0.3 mM) could scavenge 92%, while MT-I at 0.15 mM microl/ml concentrations could completely scavenge all the reactive species (2.15 x 10(15) spins/ml) generated. The results of these studies suggest that although both isoforms of MT are able to scavenge free radicals, the MT-I appears to be a superior scavenger of superoxide and 1,1 diphenyl-2-picrylhydrazyl radicals.

Metallothionein, neurotrophins and selegiline in providing neuroprotection in Parkinson's disease

The finding that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) elicits parkinsonism in human beings suggests that endogenous or xenobiotic neurotoxic compounds may be involved in the etiology of Parkinson's disease (PD). We have shown that cerebrospinal fluid (CSF) of newly diagnosed and drug untreated patients with PD contains a low molecular weight substance(s) which inhibits the growth and function of dopaminergic neurons in culture. In addition, selegiline in a dosage below the level that inhibits monoamine oxidase B (MAO-B), protects dopaminergic neurons in culture against toxic factor(s) present in the CSF of patients with PD, and the said effect is mediated via elaboration of brain-derived neurotrophic factor (BDNF). In view of the fact that 6-hydroxydopamine (6-OHDA) or MPTP causes parkinsonism by generating free radicals, and inducers of metallothionein (MT) isoforms avert the said neurotoxicity, we intended to learn whether MT isoforms were capable of scavenging free radicals. By employing electron spin resonance spectroscopy (ESR), we examined for the first time the free radical scavenging effects of MT-I and MT-II isoforms on four types of free radicals. Solutions of 0.15 mM of MT-I and 0.3 mM of MT-II scavenged the 1,1-diphenyl-2-picrylhydrazyl radicals completely. Furthermore, they were able to scavenge hydroxyl radicals generated in a Fenton reaction. Moreover, MT-I scavenged almost 90% of the superoxide generated by the hypoxanthine and xanthine oxidase system, while MT-II could only scavenge 40%. By using 2,2,6,6-tetramethyl-4-piperidone as a "spin-trap" for the reactive oxygen species (containing singlet oxygen, superoxide and hydroxyl radicals) generated by photosensitized oxidation of riboflavin, and measuring the relative signal intensities of the resulting stable nitroxide adduct, 2,2,6,6-tetramethyl-4-piperidone-1-oxyl, we observed that MT-II could scavenge 92%, while MT-I could completely scavenge all the reactive species generated. The results of this investigation are interpreted to suggest that selegiline by preventing the generation of free radicals, MT isoforms by scavenging free radicals, and neurotrophins by rescuing dopaminergic neurons are capable of attenuating oxidative stress and of providing neuro-protection in PD.

Manipulation of metallothionein expression in the regenerating rat liver using antisense oligonucleotides

Metallothioneins (MTs) are low molecular weight, zinc-binding proteins that by activating zinc metalloenzymes participate in the regulation of growth and development. The present study was designed to examine the roles of MTs in cell proliferation using an in vivo model of liver regeneration following partial hepatectomy (PH) in rats. The levels of MT-I and MT-II were studied with respect to regulation of proliferative potential, cell cycle checkpoint activity, and oxidative stress in the rat PH model. We synthesized a 17-mer antisense phosphorothioate oligodeoxynucleotide (S-ODN), named aMT, complimentary to the start site of the MT-I mRNA sequence and an appropriate control. Both S-ODNs were administered intraperitoneally at the dose of 5 mg/kg following 70% PH. MT became induced 57.4 +/- 9.8-fold following PH and the said effect became attenuated dramatically following administration of aMT. In addition, PH rats treated with aMT exhibited decreased rate of liver regeneration as measured by expression of proliferating cell nuclear antigen and elevated cell cycle checkpoint activity as determined by expression of p53. The results of these studies suggest that MT isoforms with their high thiol contents do play an important role in cellular functions and especially during stressful states induced by a broad range of mediators generating free radicals.

Opioidergic innervation of the tree shrew pineal gland: an immunohistochemical study

The tree shrew (Tupaia glis) has been described as a missing link relating primate to insectivore stock. The pineal gland of the tree shrew consists of a superficial pineal and a deep pineal, which are connected by a long and slender pineal stalk. A monoclonal antibody against leu-enkephalin was used in an immunohistochemical investigation of the tree shrew pineal gland. A moderate innervation of leu-enkephalin immunoreactive nerve fibers has been demonstrated in both superficial and deep pineal gland of the tree shrew. The density of the nerve fibers was slightly higher in the superficial pineal than that of the deep one. The number of immunoreactive nerve fibers were observed in the capsule of the pineal gland from where they entered the pineal parenchyma. Only a few immunoreactive fibers were found in the habenular area and the area rostral to the pineal recess, connecting the habenula and the deep pineal. Furthermore, some positive fibers were located in the pineal stalk. There was no evidence of leu-enkephalin immunoreactive intrapineal cells as seen in the other species of mammal. Therefore, the interspecies variation of opioidergic innervation among the mammals may exist. The lack of intrapineal perikarya is interpreted to indicate that the sources of leu-enkephalin nerve fibers were outside the gland. The anatomical location of the leu-enkephalin immunoreactive nerve fibers in the tree shrew pineal gland supports to both central and peripheral pinealopetal pathways in this species.

Pineal opioid receptors and analgesic action of melatonin

Physicians have noted since antiquity that their patients complained of less pain and required fewer analgesics at night times. In most species, including the humans, the circulating levels of melatonin, a substance with analgesic and hypnotic properties, exhibit a pronounced circadian rhythm with serum levels being high at night and very low during day times. Moreover, melatonin exhibits maximal analgesic effects at night, pinealectomy abolishes the analgesic effects of melatonin, and mu opioid receptor antagonists disrupt the day-night rhythm of nociception. It is believed that melatonin, with its sedative and analgesic effects, is capable of providing a pain free sleep so that the body may recuperate and restore itself to function again at its peak capacity. Moreover, in conditions when pain is associated with extensive tissue injury, melatonin's ability to scavenge free radicals and abort oxidative stress is yet another beneficial effect to be realized. Since melatonin may behave as a mixed opioid receptor agonist-antagonist, it is doubtful that a physician simply could potentiate the analgesic efficacy of narcotics such as morphine by coadministering melatonin. Therefore, future research may synthesize highly efficacious melatonin analogues capable of providing maximum analgesia and hopefully being devoid of addiction liability now associated with currently available narcotics.

Existence and function of opioid receptors on mammalian pinealocytes

Previous studies in our laboratories have identified a single population of opioid receptors in bovine pineal gland, which we have chosen to characterize further on pinealocytes isolated from the cow and rat pineal gland. The bovine pinealocytes isolated by trypsinization or mechanical manipulation revealed receptor density (Bmax) values of 206.95 +/- 131.15 and 220.34 +/- 11.80 fmol/mg protein, respectively, and dissociation equilibrium constant (Kd) values of 1.93 +/- 0.48 and 1.96 +/- 0.21 nM, respectively. The rat pinealocytes cultured for 7 days exhibited a [3H]diprenorphine binding site of 56 fmol/10(6) cells. Morphine (100 microM) enhanced the activity of N-acetyltransferase and the level of melatonin in rat pineal gland in culture incubated for 21 hr. The results of these studies suggest that opioidergic receptors exist on pinealocytes and they are involved in stimulating the activity of N-acetyltransferase and the synthesis of melatonin, thereby regulating the physiology of mammalian pineal gland.

Stable interaction between G-actin and neurofilament light subunit in dopaminergic neurons

Excessive accumulation of neurofilaments in the cell bodies and proximal axons of motor neurons is a major pathological hallmark of motor neuron diseases. In this communication we provide evidence that the neurofilament light subunit (68 kDa) and G-actin are capable of forming a stable interaction. Cytochalasin B, a cytoskeleton disrupting agent that interrupts actin-based microfilaments, caused aggregation of neurofilaments in cultured mesencephalic dopaminergic neurons, suggesting a possible interaction between neurofilaments and actin; which was tested further by using crosslinking reaction and affinity chromatography techniques. In the cross-linking experiment, G-actin interacted with individual neurofilament subunits and covalently cross-linked with disuccinimidyl suberate, a homobifunctional cross-linking reagent. Furthermore, G-actin was extensively cross-linked to the light neurofilament subunit with this reagent. The other two neurofilament subunits showed no cross-linking to G-actin. Moreover, neurofilament subunits were retained on a G-actin coupled affinity column and were eluted from this column by increasing salt concentration. All three neurofilament subunits became bound to the G-actin affinity column. However, a portion of the 160 and 200 kDa neurofilament subunits did not bind to the column, and the remainder of these two subunits eluted prior to the 68 kDa subunit, suggesting that the light subunit exhibited the highest affinity for G-actin. Moreover, neurofilaments demonstrated little or no binding to F-actin coupled affinity columns. The phosphorylation of neurofilament proteins with protein kinase C reduced its cross-linking to G-actin. The results of these studies are interpreted to suggest that the interaction between neurofilaments and actin, regulated by neurofilament phosphorylation, may play a role in maintaining the structure and hence the function of dopaminergic neurons in culture.

Identification of metallothionein receptors in human astrocytes

Metallothionein (MT) isoforms are low molecular weight (6000-7000 Da) zinc binding proteins containing 60-68 amino acid residues, 25-30% cysteine, no aromatic amino acids, and binding between 5-7 g zinc/mol of protein. Since the synthesis of MT is induced by endotoxin, cytokines, and glucocorticoids, MT is now considered to be an acute phase protein protecting against oxygen radicals and oxidative damages caused by inflammation, tissue injury, and stress to the central nervous system. By postulating that a specific mechanism must exist to foster the induction of MTs I and II by numerous and diversified factors, we searched for and identified for the first time, MT receptors on U373MG cell membrane preparations, by using fluoresceinated MT I isoform probe; and by employing cysteine, glutathione, and four MT isoforms to determine high affinity and specific binding. MT receptors revealed a Kd value of 0.84 nM and a Bmax of 99.82 fmol/mg protein. Moreover, MT receptors were found in greater density on the surface of aggregated astrocytes. We postulate that conditions or agents generating reactive oxygen species may influence the expression of MT receptors.

Tumor cell growth is inhibited by suppressing metallothionein-I synthesis

The effect of metallothionein (MT)-I antisense oligodeoxynucleotide (ODN) on the growth of three kinds of tumor cells was studied, since MTs may be involved in cell growth. When MT-I antisense ODN was added to leukemia P388 cells, cell growth was inhibited in a manner dependent on the dose and incubation time. MT-I antisense ODN was also inhibitory for other tumor cell lines, i.e. Ehrlich carcinoma and sarcoma 180. A significant decrease in the level of MT, but not of Zn, was observed in MT-I antisense ODN-treated cells. On the other hand, control ODN did not inhibit the cell growth appreciably. These results indicate that MT-I expression may be necessary for the growth and survival of these tumor cells.

Neurotrophins and their receptors in nerve injury and repair

Cytokines are a heterogenous group of polypeptide mediators that have been associated with activation of numerous functions, including the immune system and inflammatory responses. The cytokine families include, but are not limited to, interleukins (IL-I alpha, IL-I beta, ILIra and IL-2-IL-15), chemokines (IL-8/ NAP-I, NAP-2, MIP-I alpha and beta, MCAF/MCP-1, MGSA and RANTES), tumor necrosis factors (TNF-alpha and TNF-beta), interferons (INF-alpha, beta and gamma), colony stimulating factors (G-CSF, M-CSF, GM-CSF, IL-3 and some of the other ILs), growth factors (EGF, FGF, PDGF, TGF alpha, TGF beta and ECGF), neuropoietins (LIF, CNTF, OM and IL-6), and neurotrophins (BDNF, NGF, NT-3-NT-6 and GDNF). The neurotrophins represent a family of survival and differentiation factors that exert profound effects in the central and peripheral nervous system (PNS). The neurotrophins are currently under investigation as therapeutic agents for the treatment of neurodegenerative disorders and nerve injury either individually or in combination with other trophic factors such as ciliary neurotrophic factor (CNTF) or fibroblast growth factor (FGF). Responsiveness of neurons to a given neurotrophin is governed by the expression of two classes of cell surface receptor. For nerve growth factor (NGF), these are p75NTR (p75) and p140trk (referred to as trk or trkA), which binds both BDNF and neurotrophin (NT)-4/5, and trkC receptor, which binds only NT-3. After binding ligand, the neurotrophin-receptor complex is internalized and retrogradely transported in the axon to the soma. Both receptors undergo ligand-induced dimerization, which activates multiple signal transduction pathways. These include the ras-dependent pathway utilized by trk to mediate neurotrophin effects such as survival and differentiation. Indeed, cellular diversity in the nervous system evolves from the concerted processes of cell proliferation, differentiation, migration, survival, and synapse formation. Neural adhesion and extracellular matrix molecules have been shown to play crucial roles in axonal migration, guidance, and growth cone targeting. Proinflammatory cytokines, released by activated macrophages and monocytes during infection, can act on neural targets that control thermogenesis, behavior, and mood. In addition to induction of fever, cytokines induce other biological functions associated with the acute phase response, including hypophagia and sleep. Cytokine production has been detected within the central nervous system as a result of brain injury, following stab wound to the brain, during viral and bacterial infections (AIDS and meningitis), and in neurodegenerative processes (multiple sclerosis and Alzheimer's disease). Novel cytokine therapies, such as anticytokine antibodies or specific receptor antagonists acting on the cytokine network may provide an optimistic feature for treatment of multiple sclerosis and other diseases in which cytokines have been implicated.

The antioxidant properties of zinc and metallothionein

Support for the hypothesis that metallothionein isoforms participate in intracellular defense against reactive oxygen and nitrogen species is derived from observations that substances causing oxidative stress, such as ethanol and iron, and agents involved in inflammatory processes, such as interleukin-1 and tumour necrosis factor alpha, induce the synthesis of metallothionein. Moreover, animals deficient in metallothionein isoforms exhibit greater susceptibility to oxidative stress; metallothionein genes are transcriptionally activated in cells and tissues during oxidative stress; and over expression of metallothionein reduces the sensitivity of cells and tissues to free radical-induced injury. In this study, we have shown that the i.c.v. administration of ZnSO4 increases the synthesis of metallothionein I mRNA and metallothionein II mRNA. In addition, the i.c.v. administration of ZnSO4 enhances the concentration of zinc and in direct proportion the synthesis of metallothionein mRNAs. Agents known to generate free radicals and to cause oxidative stress such as 6-hydroxydopamine, iron, hydrogen peroxide, and various alcohols lead to induction of metallothionein in the hippocampal neurons in primary culture and in Chang liver cells in culture. In view of the fact that zinc and 6-hydroxydopamine induce the level of brain metallothionein and its mRNAs and zinc and metallothionein concentrations vary in different regions of the brain, it is postulated that metallothionein may play a major role in nullifying the iron-mediated generation of free radicals and in protecting against oxidative stress in the brain.

Amino acid composition, immunoreactivity, sequence analysis, and function of bovine hippocampal metallothionein isoforms

The high concentration of zinc in the hippocampal mossy fiber axon boutons is localized in the vesicles and is mobilized by exocytosis of the zinc-laden vesicles. Because "free" zinc in excess is a neurotoxic substance inhibiting an extensive number of sulfhydryl-containing enzymes and receptor sites, we hypothesized that low-molecular-weight zinc binding proteins must exist in the hippocampus to regulate the steady-state concentration of zinc. In this communication, we report that the bovine hippocampus synthesizes metallothionein (MT) isoforms that are similar, but not identical, to those of the rat brain MT isoforms and cross-react poorly with antibodies formed against the hepatic MT isoforms, suggesting that the immunologically dominant regions of hippocampal MT (residues 1-29) are not conserved. A comparative sequence analysis of bovine hippocampal MTs and bovine hepatic MT isoforms I and II revealed a 90% sequence identity, being mostly different in residues 1-29. The results of these studies suggest that the hippocampal MT isoforms, which are synthesized on a continuous basis, may play a role in regulating the transport, accumulation, and compartmentation of zinc in the hippocampus.

Oxidative stress and antioxidant therapy in Parkinson's disease

Parkinson's disease, known also as striatal dopamine deficiency syndrome, is a degenerative disorder of the central nervous system characterized by akinesia, muscular rigidity, tremor at rest, and postural abnormalities. In early stages of parkinsonism, there appears to be a compensatory increase in the number of dopamine receptors to accommodate the initial loss of dopamine neurons. As the disease progresses, the number of dopamine receptors decreases, apparently due to the concomitant degeneration of dopamine target sites on striatal neurons. The loss of dopaminergic neurons in Parkinson's disease results in enhanced metabolism of dopamine, augmenting the formation of H2O2, thus leading to generation of highly neurotoxic hydroxyl radicals (OH.). The generation of free radicals can also be produced by 6-hydroxydopamine or MPTP which destroys striatal dopaminergic neurons causing parkinsonism in experimental animals as well as human beings. Studies of the substantia nigra after death in Parkinson's disease have suggested the presence of oxidative stress and depletion of reduced glutathione; a high level of total iron with reduced level of ferritin; and deficiency of mitochondrial complex I. New approaches designed to attenuate the effects of oxidative stress and to provide neuroprotection of striatal dopaminergic neurons in Parkinson's disease include blocking dopamine transporter by mazindol, blocking NMDA receptors by dizocilpine maleate, enhancing the survival of neurons by giving brain-derived neurotrophic factors, providing antioxidants such as vitamin E, or inhibiting monoamine oxidase B (MAO-B) by selegiline. Among all of these experimental therapeutic refinements, the use of selegiline has been most successful in that it has been shown that selegiline may have a neurotrophic factor-like action rescuing striatal neurons and prolonging the survival of patients with Parkinson's disease.

Selegiline protects dopaminergic neurons in culture from toxic factor(s) present in the cerebrospinal fluid of patients with Parkinson's disease

The cerebrospinal fluid (CSF) of patients with Parkinson's disease (PD) contains substance(s) that inhibit the growth and functions of dopaminergic neurons. Further, selegiline, a monoamine oxidase B (MAO) inhibitor (0.125-0.250 microM) enhanced the number of tyrosine hydroxylase (TH)-positive neurons, augmented the high affinity uptake of dopamine (DA), and averted the neurotoxic effects of CSF of PD patients on rat mesencephalic neurons in culture. The neuroprotective effects of selegiline may be related either to its ability to inhibit MAO B, preventing the generation of free radicals, or to neuronal rescue property due to unknown mechanisms.

Expression and regulation of brain metallothionein

Many, but not all, zinc-containing neurons in the brain are a subclass of the glutamatergic neurons, and they are found predominantly in the telencephalon. These neurons store zinc in their presynaptic terminals and release it by a calcium-dependent mechanism. These "vesicular" pools of zinc are viewed as endogenous modulators of ligand- and voltage-gated ion channels. Metallothioneins (MTs) are low molecular weight zinc-binding proteins consisting of 25-30% cysteine, with no aromatic amino acids or disulfide bonds. The areas of the brain containing high contents of zinc such as the retina, the pineal gland, and the hippocampus synthesize unique isoforms of MT on a continuous basis. The four MT isoforms are thought to provide the neurons and glial elements with mechanisms to distribute, donate, and sequester zinc at presynaptic terminals; or buffer the excess zinc at synaptic junctions. In this cause, glutathione disulfide may participate in releasing zinc from MT. A similar nucleotide and amino acid sequence has made it difficult to obtain cDNA probes and antibodies capable of distinguishing indisputably among MT isoforms. MT-I and MT-II isoforms are found in the brain and in the peripheral tissues; MT-III isoform, possessing an additional seven amino acids, is expressed mostly in the brain and to a very minute extent in the intestine and pancreas; whereas MT-IV isoform is found in tissues containing stratified squamous epithelial cells. Since MTs are expressed in neurons that sequester zinc in their synaptic vesicles, the regulation of the expression of MT isoforms is extremely important in terms of maintaining the steady-state level of zinc and controlling redox potentials. The concentration of zinc has been shown to be altered in an extensive number of disorders of the central nervous system, including alcoholism. Alzheimer-type dementia, amyotrophic lateral sclerosis, Down's syndrome, epilepsy, Friedreich's ataxia, Guillaine-Barré syndrome, hepatic encephalopathy, multiple sclerosis, Parkinson's disease, Pick's disease, retinitis pigmentosa, retinal dystrophy, schizophrenia, and Wernicke-Korsakoff syndrome. The status of MT isoforms and other low molecular weight zinc-binding proteins in these conditions, diseases, disorders, or syndromes is being delineated at this time. Since several of these disorders, such as amyotrophic lateral sclerosis, are associated with oxidative stress, and since MT is able to prevent the formation of free radicals, it is believed that cytokine-induced induction of MT provides a long-lasting protection to avert oxidative damage.

Metallothionein in carcinogenesis and cancer chemotherapy

1. Despite considerable progress, cancer continues to remain the number one health threat to human beings. Currently, the targeted antineoplastic therapy is based on an understanding of the molecular mechanisms that govern the normal proliferation and functioning of the cellular elements. Furthermore, the gene-directed therapies and antibody-based approaches are also based on modulating specific signalling processes influencing growth factors and oncogenes that alter cellular proliferation. 2. The intracellular level of metallothionein, a low molecular weight metal binding protein consisting of 25-30% cysteine, containing no aromatic amino acids or disulfide bonds and binding between 5 and 7 g atoms of group II B heavy metals per mole protein, may play an important role in regulating cellular responsiveness to DNA interactive antineoplastic agents. For example, cells with acquired resistance to cisplatin or chlorambucil overexpress metallothionein, which tends to bind these alkylating agents to a higher extent than the non-resistant cells. Since humans synthesize several isoforms of metallothionein. It is not certain which isoforms are increased in cells with acquired resistance to anti-cancer drugs. In addition to sequestering electrophilic anti-cancer drugs, metallothionein, by regulating the activities of zinc-requiring metalloenzymes or scavenging radical species, may alter the therapeutic efficacy of antineoplastic agents.