Synthesis, Kinetics and Computational Explorations of 4-Phenylpiperazine Bearing N-(Aryl)-3-substituted-benzamides as Auspicious Tyrosinase Inhibitors

In the aimed research study, a new series of N-(aryl)-3-[(4-phenyl-1-piperazinyl)methyl]benzamides was synthesized, which was envisaged as tyrosinase inhibitor. The structures of these newly designed molecules were verified by IR, 1H-NMR, 13C-NMR, EI-MS and CHN analysis data. These molecules were screened against tyrosinase and their inhibitory activity explored that these 3-substituted-benzamides exhibit good to excellent potential, comparative to the standard. The Kinetics mechanism was investigated through Lineweaver-Burk plots which depicted that molecules inhibited this enzyme in a competitive mode. Moreover, molecular docking was also performed to determine the binding interaction of all synthesized molecules (ligands) with the active site of tyrosinase enzyme and the results showed that most of the ligands exhibited efficient binding energy values. Therefore, it is anticipated that these molecules might serve as auspicious therapeutic scaffolds for treatment of the tyrosinase associated skin disorders.

Real-World Challenges of Managing Diffuse Large B-Cell Lymphoma in a Developing Country

PURPOSE

To highlight challenges and cancer care disparities in patients of diffuse large B-cell lymphoma management in resource-constrained settings.

MATERIALS AND METHODS

This multicenter retrospective study included 738 patients from 12 public and private sector hematology-oncology centers across Pakistan. Patients were divided into limited-resource and enhanced-resource settings as per national diffuse large B-cell lymphoma (DLBCL) guidelines.

RESULTS

The median age at diagnosis was 47 years (range, 14-89). Male:female ratio was 2.5:1. Majority of the patients (69.3%) were treated in limited-resource settings. Computed tomography was used as a staging modality in 442 (60%) patients. Limited-stage DLBCL was present in 13.5% of patients, while 86.3% had advanced-stage disease at diagnosis. First-line regimens included rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone in 56% and cyclophosphamide, doxorubicin, vincristine, prednisone in 34% of patients, while 10% of patients received palliative regimens upfront. Of evaluable data, complete remission was documented in 299 (74.4%) patients, 39 (9.8%) had partial response and 63 (13.5%) had progressive disease. Disease-free survival (DFS) and overall survival (OS) status were not available for 345 (46.8%) patients at the time of data collection. Overall study cohort had a median follow-up of 2.2 years with a median OS of 3.6 years (95% CI, 3.1 to 4.1), median DFS of 3.1 years (95% CI, 2.6 to 3.6), and a 5-year OS of 40% and DFS of 36%.

CONCLUSION

Patients from low- and middle-income countries present at an earlier age and have more advanced disease. Patients were frequently lost to follow-up, and record keeping was inadequate more so in patients treated in limited-resource settings. There is a need to establish a national lymphoma registry, improve record keeping, and standardize treatments to ensure improvement in treatment outcomes.

Regulation of cell cycle and differentiation markers by pathogenic, non-pathogenic and opportunistic skin bacteria

Skin is the first line of defense against the physical, chemical and the biological environment. It is an ideal organ for studying molecular responses to biological infections through a variety of skin cells that specialize in immune responses. Comparative analysis of skin response to pathogenic, non-pathogenic, and commensal bacteria would help in the identification of disease specific pathways for drug targets. In this study, we investigated human breast reduction skin responses to Cutibacterium acnes (C. acnes), Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), and TLR1/2 agonist using Affymetrix microarray chips. The Pam3CSK4 solution and bacterial cultures were prepared and inoculated in steel rings, that were placed on the acetone treated epidermis in a petri dish. After 24 h incubation, 8 mm punch biopsies were taken from the center of the ring, and RNA was extracted. The genome-wide expression was then analyzed using Affymetrix HG-133A gene chip microarray. We found that the C. acnes and S. aureus boosted the production of extracellular matrix components and attenuated the expression of differentiation markers. The above responses were mediated through the TLR2 pathway. Skin also responded to S. aureus and C. acnes by inducing the genes of the cell cycle machinery; this response was not TLR2-dependent. S. aureus induced, whereas C. acnes suppressed the genes associated with apoptosis; this was also not TLR2-dependent. Moreover, S. epidermis apparently did not lead to changes in gene expression. We conclude that the breast reduction skin is a very useful model to study the global gene expression in response to bacterial treatments.

Association of TNF-α polymorphisms (-857, -863 and -1031), TNF-α serum level and lipid profile with acne vulgaris

Background

Acne is an inflammatory condition principally affected by genetic and dietary factors. Investigation into functional polymorphisms of TNF-α gene and their association with acne vulgaris will be helpful in exploring genetic influence on skin immune mediated inflammatory events. In the present study, we analyzed association of TNF-α gene polymorphisms, its expression levels and lipid profiles in a large cohort of acne patients and controls.

Methods

We used PCR-RFLP to study association of TNF-α polymorphisms at −857C/T, −863C/A and −1031 T/C sites with acne vulgaris. Lipid profiles were measured using enzymatic end-point method. The serum levels of TNF-α and apolipoprotein a were measured using ELISA. NIH, LDlink was used to investigate patterns of linkage disequilibrium across south Asian reference genome (Punjabi from Lahore Pakistan).

Results

We found that TNF-α −863 polymorphism is strongly associated with acne in overall population as well as in gender and severity based groups of acne patients. Polymorphisms at −863 and −1031 position were in linkage disequilibrium. Importantly, TNF-α serum level was significantly increased in acne patients with severe disease symptoms. Furthermore, levels of total cholesterol (TC) and triglycerides (TG) were significantly increased, whereas high density lipoprotein cholesterol (HDL-C) level was significantly decreased in acne patients. The levels of apolipoprotein a varied widely in studied populations and no significant difference was found in the analyzed groups.

Conclusion

In conclusion, we found that TNF-α expression increases in acne patients affected by TNF-α polymorphisms, and that the lipid profile is specifically disrupted in acne patients.

Role of resistin genetic variations in knee osteoarthritis pathogenesis, a cross sectional study

Osteoarthritis (OA) is a serious health concern globally and is recognized by degradation of articular cartilage, bone remodeling and synovial inflammation. Resistin is an adipokine that shown to be involved in inflammatory process associated with OA. Aim of the current study was to estimate the link of resistin gene polymorphisms (- 420 C>G, + 299 G>A) with genetic susceptibility of knee OA in a Pakistani population. 280 patients and 308 age and sex matched controls were recruited in this case-control study. Genotype and allele frequencies were evaluated by Polymerase chain reaction-Restriction Fragment Length Polymorphism. Resistin concentration was measured by immunoassay. A significant difference in allele and genotype frequency was observed for both study groups. Resistin - 420 mutant genotype was associated with an increased susceptibility to OA (p = 0.001). Similarly, resistin + 299 GA + AA genotypes showed a relation with an elevated risk of knee OA compared to GG genotype (p = 0.01). Moreover, the mutant alleles frequency was significantly high in patient group as compared to healthy individuals for both loci (p < 0.01). Resistin - 420/+ 299 alleles haplotype analysis demonstrated that mutant alleles were more prevalent in OA affected individuals compared to healthy subjects (p < 0.05). The serum resistin levels were not remarkably different in patient vs. control group (p = 0.9). Further, the circulating resistin level was not found to be influenced by - 420G and + 299A alleles and non significant differences were observed in resistin concentration in mutant vs. wild type genotypes for both SNPs (p > 0.05). Our data suggest an association between investigated resistin genetic variants and knee OA susceptibility in our population. This is the first report to show association between investigated single nucleotide polymorphisms and OA among any population.

Interplay of N acetyl cysteine and melatonin in regulating oxidative stress-induced cardiac hypertrophic factors and microRNAs

Early and specific diagnosis of oxidative stress linked diseases as cardiac heart diseases remains a major dilemma for researchers and clinicians. MicroRNAs may serve as a better tool for specific early diagnostics and propose their utilization in future molecular medicines. We aimed to measure the microRNAs expressions in oxidative stress linked cardiac hypertrophic condition induced through stimulants as Endothelin and Isoproterenol. Cardiac hypertrophic animal models were confirmed by BNP, GATA4 expression, histological assays, and increased cell surface area. High oxidative stress (ROS level) and decreased antioxidant activities were assessed in hypertrophied groups. Enhanced expression of miR-152, miR-212/132 while decreased miR-142-3p expression was observed in hypertrophic condition. Similar pattern of these microRNAs was detected in HL-1 cells treated with H₂O₂. Upon administration of antioxidants, the miRNAs expression pattern altered from that of the cardiac hypertrophied model. Present investigation suggests that oxidative stress generated during the cardiac pathology may directly or indirectly regulate anti-hypertrophy pathway elements through microRNAs including antioxidant enzymes, which need further investigation. The down-regulation of free radical scavengers make it easier for the oxidative stress to play a key role in disease progression.

Current Trends of Cardiovascular Risk Determinants in Pakistan

We carried out a case control study to determine the prevalence of various cardiovascular risk factors in a Pakistani population. A total of 835 patients (555 males and 280 females) and 794 control subjects (486 males and 308 females) were recruited in this study. Patients with documented history of coronary artery disease (CAD) were included. We assessed major risk factors such as age, body mass index (BMI), hypertension and dyslipidemia, using pre-specified definitions. A comparative analysis of the biochemical and clinical parameters was carried out between controls and patients using student's t test. We observed that the cardiovascular disease (CVD) risk factors were more prominent in the patient group as compared to the controls (P < 0.05). In the whole studied population females had increased levels of total cholesterol (TC) (P = 0.01), triglyceride (TG) (P = 0.02), and very low density lipoprotein cholesterol (vLDL-C) (P = 0.02) as compared to males. Among patients group all the risk factors were significantly higher and more prevalent in females when compared with male patients (P < 0.05). The study population was also analyzed according to the smoking status and BMI to study the effect of these risk factors independently. The smokers and study subjects with raised BMI had significantly raised blood pressure and cholesterol levels. The role of age as a risk factor was also investigated in the current study. The persons with age ≤45 years had the highest levels of lipid profile including TC, TG, low density lipoprotein cholesterol (LDL-C), vLDL-C and high density lipoprotein cholesterol (HDL-C) among the three (≤45, 46-55, ≥56 years) groups (P < 0.05). In conclusion, the present study demonstrates an increased propensity of CVD risk factors at a younger age with female preponderance. Moreover, hypertension and dyslipidemia are the most prominent of the risk factors.

Variants of resistin gene and the risk of idiopathic dilated cardiomyopathy in Pakistan

BACKGROUND

In cardiovascular disease phenotypes, a genetic factor is an important determinant of both familial and non-familial dilated cardiomyopathies. Resistin is a novel adipocyte derived peptide, associated with inflammation and suggested to be involved in contractile abnormalities of cardiomyocytes.

METHODS

In this study, we examined the association of the RETN SNPs in - 420 and + 299 in patients with idiopathic dilated cardiomyopathy (IDCM). Patients with IDCM (n = 250) and healthy controls (n = 250) were enrolled in this study. RETN genotyping was performed by using PCR-RFLP method.

RESULTS

RETN - 420C > G and + 299G > A polymorphisms were significantly more prevalent in patient group vs. controls (P < 0.0001 and P = 0.0007, respectively). GG genotype at - 420 and AA genotype at + 299 were higher in the patient group compared with healthy controls (OR = 11.4, P < 0.0001, and OR = 2.3, P = 0.030, respectively). We found that the - 420G allele increased the risk of developing IDCM in patients (P < 0.0001). Moreover, there was a significant difference between G and A alleles at RETN + 299 from IDCM cases and controls (P = 0.0032). The RETN - 420G and + 299A haplotypes were more prevalent in the patient vs. control group (P < 0.0001).

CONCLUSION

The results suggest that the RETN - 420C > G and + 299G > A polymorphisms may have a role in the pathogenesis of IDCM.

The tumor necrosis factor-α -238G/A and IL-6 -572G/C gene polymorphisms and the risk of idiopathic dilated cardiomyopathy: a meta-analysis of 25 studies including 9493 cases and 13,971 controls

BACKGROUND

Inflammation plays an imperative role in the etiology of cardiovascular diseases (CVD). The role of cytokines in the development and progression of idiopathic dilated cardiomyopathy (IDCM) is still uncertain. The current study was conducted to evaluate the association of tumor necrosis factor-α (TNF-α) -238G/A and IL-6 -572G/C gene polymorphism with IDCM in a Pakistani population.

METHODS

IDCM cases (n=250) and healthy controls (n=300) were genotyped using PCR-RFLP.

RESULTS

The variant genotypes of both the loci showed significant differences between patients and controls (p<0.05). However, -238G/A polymorphism did not show association with the disease in the presence of covariates. We also conducted a meta-analysis of both the loci with regards to CVD in accordance with the Prisma checklist. No significant relation of the TNF-α -238G/A polymorphism with CVD was found; however, this single nucleotide polymorphism (SNP) showed an association with the disease in the Asian population after subgroup analysis (p=0.01). Whereas, the IL-6 -572G/C polymorphism showed that the variant genotype (GC+CC) was associated with higher risk of CVD in contrast to the GG genotype. Furthermore, subgroup meta-analysis demonstrated a significant association of the -572 polymorphism with CVD in Asians, but no association was observed among Western populations with this SNP.

CONCLUSIONS

Our findings support an association between the IL-6 -572G/C polymorphism and IDCM risk. The role of the TNF-α -238G/A polymorphism in IDCM is still unclear. Further studies are warranted to determine the serum cytokine levels in relation to the cytokines' SNP in diverse ethnic groups to ascertain the molecular basis of the disease pathology.

Association between tumour necrosis-α gene polymorphisms and acne vulgaris in a Pakistani population

BACKGROUND

The cytokine tumour necrosis factor (TNF)-α is a well-studied potent candidate mediator that is systemically involved in a variety of inflammatory diseases. Several single nucleotide polymorphisms (SNPs) of the TNF-α gene have been studied with regard the pathogenesis of acne vulgaris, but the results have been inconclusive.

AIM

This case-control study investigated the association of the TNF -308 G>A and -238 G>A SNPs with acne vulgaris in a high-risk Pakistani population.

METHODS

In total, 160 healthy controls and 140 patients with acne were enrolled in this study. Polymorphisms were determined by PCR and restriction fragment length polymorphism analysis.

RESULTS

Our data showed that the TNF -308 G>A and TNF -238 G>A SNPs were present at a significantly higher rate in cases than in controls (P < 0.01 and P < 0.02; respectively). There was a significant difference between the G and A alleles from patients with acne and controls for -308 G>A (OR = 1.5, 95% CI = 1.07-2.19, P < 0.02) and -238 G>A (OR=1.6, 95% CI = 1.06-2.44, P = 0.02) genotype. Moreover, the severity of acne was significantly associated with TNF genotype (TNF -308 G>A: χ² = 34.6, P < 0.001; TNF -238 G>AL χ² = 12.9, P < 0.01).

CONCLUSION

Our data suggest that the TNF -308 G>A and TNF -238 G>A SNPs may contribute to the pathogenesis of acne in the study population. Furthermore, patients with severe acne showed an increased frequency of mutant TNF genotypes at -308 and -238 compared with patients with less severe acne.

N-Acetyl Cysteine Inhibits Endothelin-1-Induced ROS Dependent Cardiac Hypertrophy through Superoxide Dismutase Regulation

Objective

Oxidative stress down regulates antioxidant enzymes including superoxide dismutase (SOD) and contributes to the development of cardiac hypertrophy. N-Acetyl cysteine (NAC) can enhance the SOD activity, so the aim of this study is to highlight the inhibitory role of NAC against endothelin-1 (ET-1)-induced cardiac hypertrophy.

Materials and Methods

In this experimental study at QAU from January, 2013 to March, 2013. ET-1 (50 µg/kg) and NAC (50 mg/kg) were given intraperitoneally to 6-day old neonatal rats in combination or alone. All rats were sacrificed 15 days after the final injection. Histological analysis was carried out to observe the effects caused by both drugs. Reactive oxygen species (ROS) analysis and SOD assay were also carried out. Expression level of hyper- trophic marker, brain natriuretic peptide (BNP), was detected by western blotting.

Results

Our findings showed that ET-1-induced cardiac hypertrophy leading towards heart failure was due to the imbalance of different parameters including free radical-induced oxidative stress and antioxidative enzymes such as SOD. Furthermore NAC acted as an antioxidant and played inhibitory role against ROS-dependent hypertrophy via regulatory role of SOD as a result of oxidative response associated with hypertrophy.

Conclusion

ET-1-induced hypertrophic response is associated with increased ROS production and decreased SOD level, while NAC plays a role against free radicals-induced oxidative stress via SOD regulation.

Transcriptional changes associated with resistance to inhibitors of epidermal growth factor receptor revealed using metaanalysis

BACKGROUND

EGFR is important in maintaining metabolic homeostasis in healthy cells, but in tumors it activates downstream signaling pathways, causing proliferation, angiogenesis, invasion and metastasis. Consequently, EGFR is targeted in cancers using reversible, irreversible or antibody inhibitors. Unfortunately, tumors develop inhibitor resistance by mutations or overexpressing EGFR, or its ligand, or activating secondary, EGFR-independent pathways.

METHODS

Here we present a global metaanalysis comparing transcriptional profiles from matched pairs of EGFR inhibitor-sensitive vs. -resistant cell lines, using 15 datasets comprising 274 microarrays. We also analyzed separately pairs of cell lines derived using reversible, irreversible or antibody inhibitors.

RESULTS

The metaanalysis identifies commonalities in cell lines resistant to EGFR inhibitors: in sensitive cell lines, the ontological categories involving the ErbB receptors pathways, cell adhesion and lipid metabolism are overexpressed; however, resistance to EGFR inhibitors is associated with overexpression of genes for ErbB receptors-independent oncogenic pathways, regulation of cell motility, energy metabolism, immunity especially inflammatory cytokines biosynthesis, cell cycle and responses to exogenous and endogenous stimuli. Specifically in Gefitinib-resistant cell lines, the immunity-associated genes are overexpressed, whereas in Erlotinib-resistant ones so are the mitochondrial genes and processes. Unexpectedly, lines selected using EGFR-targeting antibodies overexpress different gene ontologies from ones selected using kinase inhibitors. Specifically, they have reduced expression of genes for proliferation, chemotaxis, immunity and angiogenesis.

CONCLUSIONS

This metaanalysis suggests that 'combination therapies' can improve cancer treatment outcomes. Potentially, use of mitochondrial blockers with Erlotinib, immunity blockers with Gefitinib, tyrosine kinase inhibitors with antibody inhibitors, may have better chance of avoiding development of resistance.

Insulin over expression induces heart abnormalities via reactive oxygen species regulation, might be step towards cardiac hypertrophy

Insulin is known to regulate blood&mdash;glucose level and promote its utilization as an energy source in cardiac tissues under normal physiological conditions as well as stimulates signaling pathways that involved cell growth and proliferation. Although recently insulin generated free radicals via NAD(P)H has been documented but the molecular mechanism is still under investigation. The aim of present study is to elucidate the reactive oxygen species (ROS) dependent possible role of insulin in cardiac abnormalities, including hypertrophy by regulation of antioxidants enzyme (SOD) activity. In the current study, 60 cardiac patients and 50 healthy individuals as well as the rat model with insulin administration were under investigation. Oxidant, anti&mdash;oxidant biochemical assays, hypertrophic marker expression via immunobloting and histopathology were performed. We observed statistically significant elevation of the reactive oxygen species level in the serum of patients as well as in the insulin administrated rat model, a mild expression of cardiac marker in experimental models along with abnormal histopathology of hearts. However, super oxide dismutase free radical scavenger activity was down regulated upon insulin treatment compared to control rats. Conclusively, the present study showed that over expression of insulin might stimulate cardiac hypertrophic signal via up regulation of free radicals and down regulation of antioxidants enzymes including SOD activity.

TNF-alpha-308G>A polymorphism and the risk of familial CAD in a Pakistani population

A case-control and trio-families study was performed to establish a potential association between TNF-alpha gene promoter SNPs at -308 and -238, and occurrence of CAD in a Pakistani population. In the first phase, 150 patients and 150 controls were enrolled in the case-control association study. In the second phase, heritability of susceptible alleles was investigated from 88 trio-families with CAD affected offspring. Biochemical analysis of lipids and hs-CRP was carried out spectrophotometrically, while serum TNF-alpha concentrations were determined by enzyme-linked immunosorbent assay. Genotyping of the TNF-alpha SNPs were determined by PCR-RFLP method. Elevated serum TNF-alpha and hs-CRP were observed from CAD vs. controls (P<0.0001; for both). The evaluation of TNF-alpha-308G>A polymorphism in case-control study revealed that the said SNP was significantly associated with the increased risk of CAD. The findings demonstrated a significant link between the TNF-alpha variant allele A at -308 and CAD (P=0.0035), whereas the -238 SNP was not associated with the disease. Haplotype A-G of the TNF-alpha gene at -308G>A and -238G>A showed higher frequency in the patient group compared with controls (P<0.05). Moreover, data showed preferential transmission of the disease susceptible allele A at TNF-alpha-308 from parent to affected offspring in a trio-family study (P<0.0001). The current research leads to conclusion that the TNF-alpha-308G>A polymorphism is associated with CAD in the study population. Furthermore, for the first time, we showed that the TNF-alpha-308A allele was significantly associated with the familial CAD in our high risk population.

The interleukin-6 and interleukin-1A gene promoter polymorphism is associated with the pathogenesis of acne vulgaris

Acne vulgaris is a skin disorder with a complex pathogenesis. Better treatment strategies require comprehensive knowledge of molecular factors contributing to the acne pathophysiology. Recent studies are focused on investigating the influence of inflammatory cytokines on the disease. This case-control study investigated the association of IL-6-572 G/C and IL-1A-889 C/T gene polymorphisms with acne in a Pakistani population. Pakistani subjects (380 healthy controls and 430 acne patients) were enrolled in this study. Polymorphism in the promoter region of IL-6-572 and IL-1A-889 was determined by polymerase chain reaction and restriction fragment length polymorphism. The IL-6-572 and IL-1A-889 variant genotypes were significantly associated with the acne pathogenesis. The IL-6-572C and the IL-1A-889T alleles were significantly high in the patient vs. control group (p < 0.0001 for both loci). The IL-6-572 G/C and IL-1A-889 C/T variant allele haplotypes showed significantly high prevalence in patients with acne; G-T (P = 0.0014), C-C (P < 0.0001), and C-T (P < 0.0001). This is the first report on the association between the IL-6-572 G/C polymorphism and acne among any population. The IL-1A-889 C/T polymorphism is also significantly linked with acne in the study population; the -889 C/T association with acne has been reported in one ethnic group previously. Our findings suggest that the IL-6-572C and IL-1A-889T alleles may contribute to the pathogenesis of acne in a Pakistani population. Further studies are required to verify these findings in other populations.

Gender differences in normal left ventricle of adult FVB/N mice due to variation in interleukins and natriuretic peptides expression levels

This study examined the sex differences for physical, morphological, histological, mRNA, and protein expression levels changes for interleukins and natriuretic peptides in left ventricle (LV) of two groups of adult FVB/N mice; males (WM) and females (WF). LV morphological, histological, reverse transcription and quantitative real-time PCR (RT-PCR), and immunohistochemical (IHC) alterations were determined in FVB/N mice at 34-35 weeks on gender basis. Confirming the gender dimorphism, FVB/N males (WM) illustrated a significant reduction in ANP and IL1-A levels as well as significantly increased body weight (BW (gm)), tibia length (TL (mm)), heart weight (HW (mg)), heart weight-to-body weight (HW/BW (mg/gm)) ratio, heart weight-to-tibia length (HW/TL (mg/mm)) ratio, left ventricle weight (LV (mg)), left ventricle-to-body weight (LV/BW (mg/gm)) ratio, and left ventricle-to-tibia length (LV/TL (mg/mm)) ratio, left ventricular (LV) cardiomyocyte diameter, high BNP, NPRA, IL-1B, and IL1R1 expression in comparison with FVB/N females (WF). Gender differences in relation to left ventricle (LV) may be due to differences in the interleukins and natriuretic peptides levels as an outcome of sex related hormones.

Polymorphisms of tumor necrosis factor-alpha and interleukin-6 gene and C-reactive protein profiles in patients with idiopathic dilated cardiomyopathy

BACKGROUND AND OBJECTIVES

The tumor necrosis factor-alpha (TNF-a) and interleukin (IL)-6 gene polymorphism has a controversial role in the pathogenesis of cardiovascular disease among different populations. The effect of the cytokine's gene polymorphism on idiopathic dilated cardiomyopathy (IDCM) is still unresolved. The current study aimed to evaluate the association of the TNF-a -308 G/A and IL-6 -174 G/C polymorphism with IDCM in a Pakistani population.

DESIGN AND SETTINGS

Blood samples for this case-control study were collected from the cardiology out.patient department of multiple cardiology centers of Rawalpindi/Islamabad, Pakistan, between July 2012 and December 2012.

PATIENTS AND METHODS

IDCM cases (number [n]=250) and healthy controls (n=300) were genotyped using polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

The TNF-a -308 variant genotypes GA and AA were more prevalent in patients compared with the control group (P < .0001). Similarly, the IL-6 -174 variant genotypes GC and CC showed a high prevalence in patients with IDCM compared with healthy controls (P=.0019). IDCM cases had a higher prevalence of the TNFa-308A (P < .0001) and the IL-6 -174C (P=.0008) mutant alleles than did the control group. The IDCM cases bearing the TNF-a-308 and IL-6 variant genotypes revealed elevated levels of high-sensitivity C-reactive protein (hs-CRP) when compared with the corresponding controls (P < .05).

CONCLUSION

The TNF-a -308 G/A and IL-6 -174 G/C gene polymorphisms and high levels of hs-CRP may be associated with the pathogenesis of IDCM in the study population.

Interplay of Phosphorylated Apoptosis Repressor with CARD, Casein Kinase-2 and Reactive Oxygen Species in Regulating Endothelin-1-Induced Cardiomyocyte Hypertrophy

OBJECTIVE(S)

The role of the Apoptosis repressor with caspase recruitment domain (ARC) in apoptosis and in certain hypertrophic responses has been previously investigated, but its regulation of Endothelin-1 induced cardiac hypertrophy remains unknown. The present study discusses the inhibitory role of ARC against endothelin-induced hypertrophy.

RESULTS

In present study Endothelin treated cardiomyocytes were used as a hypertrophic model, that were subsequently treated with adenovirus ARC and its mutant at different multiplicity of infections. Casein-kinase-2 inhibitors were used to produce dephosphorylated ARC and to study its effect on hypertrophy. Hypertrophy was assessed by cell surface area measurement, Atrial-natriuretic-Factor mRNA analysis and total protein assay. Reactive oxygen species analysis was carried out using the dichlorofluorescin-diacetate (DCFH-DA) assay. Over expression of ARC significantly inhibits Endothelin-induced cardiomyocyte hypertrophy. The nonphosphorylated mutant ARC (T149 A) remained unable to control endothelin-induced hypertrophy, suggesting a vital role for ARC phosphorylation in regulation of its activity. Sensitization study has been carried out to check the role of endogenous ARC using casein-kinase inhibitors. Finally, the significant role of ARC in regulating reactive oxygen species -mediated control of endothelin induced hypertrophy has also been assessed. Conclusion : Conclusively, present study showed the vital and potential therapeutic interventional role of ARC in preventing endothelin-1-induced cardiomyocyte hypertrophy. The regulation of hypertrophic pathway by ARC relies on blunting the reactive oxygen species attack. This study further suggests a mediatory role of casein-kinase-2 in Endothelin-induced hypertrophy, mainly through its phosphorylation of ARC.

Diameter-controlled synthesis of α-Mn2O3 nanorods and nanowires with enhanced surface morphology and optical properties

Single crystalline α-Mn(2)O(3) nanorods, and nanowires with and without nanoparticles on them have been successfully synthesized by a template-free hydrothermal route. The variation in hydrothermal temperature has not only affected the diameter of the nanostructure but also noticeably affected the morphology and optical properties of the α-Mn(2)O(3) nanostructure. The influence of temperature on the diameter, crystallinity, surface morphology and optical properties of the α-Mn(2)O(3) nanostructure have been characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, transmission electron microscopy, high resolution transmission electron microscopy, Raman spectroscopy and UV-visible spectroscopy and photoluminescent (PL) spectroscopy. The results showed in our experimental conditions that single crystalline nanorods of the α-Mn(2)O(3) were obtained at a temperature of 180 °C, while single crystalline nanowires were obtained by increasing the temperature to 240 and 300 °C. Nanowires with nanoparticles on them were obtained by increasing the temperature to 240 °C and nanowires without nanoparticles on them were obtained by increasing the temperature to 300 °C. The nanorods and nanowires obtained had a well-defined morphology. The nanowires synthesized at 300 °C exhibited an intense orange band PL spectrum.

Resistin gene promoter region polymorphism and the risk of hypertrophic cardiomyopathy in patients

Resistin, a novel cytokine, is associated with an inflammatory process and is suggested to induce hypertrophy in rat cardiomyocytes. Resistin gene expression has not been investigated in patients with hypertrophic cardiomyopathy (HCM). This study investigates resistin levels in HCM patients and healthy controls and the molecular basis for the regulation of the resistin gene (RETN) in a Pakistani population. Patients with HCM (n = 105) and healthy individuals (n = 110) were enrolled in this investigation. Serum resistin levels were determined by enzyme-linked immunosorbent assay (ELISA). RETN genotyping was performed by polymerase chain reaction (PCR) and DNA sequencing. Our data showed a statistically significant increase in resistin levels from HCM patients compared with healthy subjects (6.3 +/- 2.7 ng/mL in patients vs 3.4 +/- 2.1 ng/mL in controls, P < 0.0001). The RETN -420 C > G polymorphism was significantly high in patients with HCM compared with the control group (P < 0.001). There was a significant difference between the C and G alleles from HCM cases and controls (odds ratio [OR] = 3.54, 95% confidence interval [CI] = 2.36-5.30, P < 0.0001). Logistic-regression analysis showed that the increased resistin levels, and the RETN-420 C > G polymorphism were significantly associated with HCM. Our data suggest that the elevated resistin levels and the RETN -420 C > G polymorphism may be associated with cardiac hypertrophy in the study population.

In vitro evaluation of vascular endothelial growth factor (VEGF)-eluting stents

BACKGROUND

Vascular endothelial growth factor (VEGF) is a specific endothelial cell mitogen. It promotes re-endothelialisation of the damaged vessel surface seen after stenting. Stent thrombosis and in-stent restenosis are partly related to endothelial denudation caused by stent implantation. We propose using hydrocarbon polymer-coated stents immersed in VEGF to speed re-endothelialisation and reduce the risk of stent thrombosis and restenosis.

METHODS

Stents (3 x 20 mm) were immersed in VEGF solutions and maximal VEGF absorption calculated. VEGF release from these stents was measured in a perfusion circuit. Delivery of VEGF to arterial wall was measured. Sterile VEGF-loaded stents were cultured with human umbilical vein endothelial cells.

RESULTS

18.5 +/- 4.1 microg VEGF was absorbed, 80% of which was released over 9 days; 11 +/- 6.8% of the initial VEGF loaded was delivered to the vessel wall. Cells exposed to VEGF-eluting stents showed an 11% increase in growth relative to controls.

CONCLUSION

VEGF may be a candidate for stent-based delivery and may increase the rate of endothelialisation in vivo.

Vascular endothelial growth factor (VEGF)-eluting stents: in vivo effects on thrombosis, endothelialization and intimal hyperplasia

Local drug delivery by stent can reduce in-stent restenosis. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen. After stenting, the arterial wall is almost denuded of endothelium. This loss of endothelium contributes to the smooth muscle cell (SMC) proliferation seen in restenosis, since the endothelium actively inhibits SMC hyperplasia. Over time, the endothelium recovers and SMC hyperplasia is arrested. The capacity of VEGF-coated stents to accelerate re-endothelialization, and to therefore reduce restenosis and thrombosis, was tested in this study. Radiolabeled VEGF was absorbed onto stents and released over nine days in an in vitro perfusion circuit. VEGF-coated stents were deployed in arterial segments to study local tissue release. A New Zealand White rabbit iliac artery model for stent implantation was used. Re-endothelialization and thrombosis were assessed after seven days. Further animals were examined 28 days post-procedure for in-stent restenosis. Stented vessels were resin-embedded, sectioned and stained. Intimal thickening was calculated using computerized morphometry. In vitro, the stents released 80% of the initial load over nine days. At seven days, thrombus was significantly reduced (12.5 mg for controls versus 0 mg for VEGF; p = 0.014). No beneficial effect was seen on endothelialization, nor on intimal hyperplasia. Neointimal area was 2.2 0.9 mm2 for controls versus 2.4 1.8 mm2 for VEGF (p = 0.8). These VEGF-eluting stents do not accelerate re-endothelialization or inhibit restenosis. Stent thrombosis appears to be reduced, which may make these stents less thrombogenic and be valuable in higher-risk cases.

Tumor necrosis factor-alpha antibody eluting stents reduce vascular smooth muscle cell proliferation in saphenous vein organ culture

Expression of TNF-alpha a vascular smooth muscle cell (VSMC) mitogen, is up-regulated in injured/proliferating vessel wall. Coronary stents are tested worldwide for their use as local drug delivery devices to address vascular pathophysiology. In this study we have investigated the effect of TNF-alpha antibody eluting stents on VSMC proliferation in human saphenous vein (HSV) organ culture. The adsorption and elution characteristics of TNF-alpha antibody was assessed using stent wires. The stents adsorbed up to 0.25 microg of TNF-alpha antibody/mg of stent and showed a biexponential elution curve, with 34.4% (SD 4.4%) antibody remaining on the stent after 72 h of washing in a perfusion circuit. TNF-alpha antibody delivery from loaded stents to the vessel wall was assessed ex vivo. TNF-alpha and proliferating cell nuclear antigen (PCNA) expression in the vascular specimens was assessed by immunostaining or ELISAs. TNF-alpha ELISAs showed a significant increase in the cytokine levels from the vascular lysates prepared from proliferating tissue culture compared with fresh vein (P < 0.05). Immunohistochemical localization showed an increase in the PCNA positivity of VSMC from these cultures. PCNA staining was barely detected from the fresh tissue. However, a decrease in PCNA staining was observed from tissue sections of venous segments cultured with TNF-alpha antibody eluting stents. PCNA ELISAs demonstrated a 23.7% decline in the antigen levels from the day 7 tissue cultured with such loaded stents. In conclusion, activated VSMC in tissue culture showed an up-regulation of TNF-alpha cytokine, in association with an increase in the PCNA expression in the vessel wall. The local neutralization of this cytokine with TNF-alpha antibody eluting stents reduced VSMC proliferation in the wall. We suggest that TNF-alpha antibody eluting stents may limit restenosis in vivo, which may have important clinical benefits.

Human internal mammary artery organ culture model of coronary stenting: a novel investigation of smooth muscle cell response to drug-eluting stents

Local drug delivery by coronary stents is of current research interest. Organ culture of human vascular tissue is a model of intimal hyperplasia. We report an ex vivo organ culture model of stented vessels. This allows stent–artery interactions to be studied in living tissue. The recognized anti-restenosis agent paclitaxel was chosen to test the organ culture model. Mammary artery specimens were cultured ‘closed’ (i.e. without opening them flat) for 72h. Phosphocholine-coated stents, half of them loaded with the anti-restenosis drug paclitaxel, were implanted. The absorption and elution characteristics of paclitaxel were established. Artery tissue remained viable at 72h when cultured closed, despite stent implantation. Specimens developed smooth muscle cell proliferation. The stents absorbed up to 127±29μg of paclitaxel, with a biphasic elution curve. A mean of 13% of the absorbed paclitaxel remained after a 24h perfusion. In mammary artery, these paclitaxel stents reduced or abolished smooth muscle cell proliferation compared with controls. This model allows the effects of stenting on human arterial tissue to be studied for at least 72h, long enough to demonstrate effects on smooth muscle cell proliferation. Phosphocholine-coated stents absorb adequate doses of paclitaxel, which is eluted gradually, inhibiting muscle cell proliferation. Such an organ culture model of stented mammary artery will provide useful data in addition to that from animal or cell culture models of drug-eluting stents.

Plasminogen activator and plasminogen activator inhibitor gene expression in human saphenous vein organ culture

We describe the expression of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) in saphenous vein culture. Smooth muscle cells (SMC) are quiescent in fresh tissue, whereas these cells acquire a proliferating phenotype when venous segments are cultured in the presence of serum. t-PA and PAI-1 were localized immunohistochemically and quantified using biochemical techniques. t-PA and PAI-1 mRNA was quantified by reverse transcription polymerase chain reaction (RT--PCR) assay. Immunostaining showed an increase in the positivity of proliferating cell nuclear antigen (PCNA) from 10-day tissue culture. Tissue sections from fresh vein showed minimal t-PA and maximal PAI-1 immunostaining. In contrast, 10-day cultures showed an increase in t-PA and a decline in PAI-1 staining. Biochemical analysis revealed a 118% increase in t-PA and a 50% decrease in PAI-1 antigen levels from 10-day tissue cultures. RT--PCR demonstrated that the mRNA encoding t-PA increased, while PAI-1 decreased after 10 days of culture. In conclusion, venous culture showed an up-regulation of t-PA and a repression of PAI-1 gene expression during SMC proliferation in the vessel wall. The PAI-1 repression observed in venous culture is in contrast to the situation observed in human atheroma. A shift in the t-PA/PAI-1 balance may have a role in vascular remodeling.

Galectin 1 is involved in vascular smooth muscle cell proliferation

OBJECTIVE

Smooth muscle cell (SMC) migration and proliferation are the key steps in the development of atherosclerosis and restenosis. Matricellular proteins have been implicated in cell adhesion, migration and proliferation. Here we investigated the role of the matricellular protein galectin-1 (Gal-1), a beta-galactoside-binding lectin, in SMC proliferation in atheroma and DNA synthesis in cell culture.

METHODS

Protein expression was visualised by tissue section immunostaining. RNA expression was analysed using Northern blot analysis. DNA synthesis of human vascular SMCs was determined by 3H-thymidine incorporation. Recombinant glutathione S-transferase-galectin-1 fusion protein (Gal FP) binding to extracellular matrix (ECM) proteins was measured by ELISA. Gal-1 binding to cells and ECM was estimated using 125I-labelled Gal FP.

RESULTS

Prominent Gal-1 staining coincided with SMC proliferation in human coronary endarterectomy samples in organoid culture. In cell culture, Gal-1 mRNA was upregulated in growing SMCs. Gal FP increased serum-induced DNA synthesis of human SMCs on plastic or endogenous ECM, but not of a rat PAC1 SM cell line. Also, Gal FP slightly increased SMC adhesion to ECM. SMCs exhibited a complex pattern of receptor-ligand interactions with Gal FP. The Gal-1 binding to SMCs was much stronger than to ECM, produced by these SMCs. We identified new ECM proteins: thrombospondin, vitronectin and osteopontin, which bound to Gal FP in a dose- and beta-galactoside-dependent manner in ELISA.

CONCLUSIONS

Gal-1 binding to SMCs was stronger than to ECM, although ECM of atherosclerotic blood vessels contained additional ECM proteins which bound to Gal-1. Gal-1 was upregulated during SMC growth and Gal FP enhanced serum-induced DNA synthesis in SMCs. Overall, Gal-1 upregulation is likely to provide a reinforcement of serum-induced events during vascular injury.

Ultrasonographic renal size in individuals without known renal disease

OBJECTIVE

In order to establish some preliminary data of our population, we determined the ultrasonographic kidney dimensions in individuals without known renal disease. We assessed whether age, sex, side, body mass index (BMI) and presence or absence of diabetes mellitus and hypertension affect the renal size.

METHODS

Ultrasonographic kidney measurements were performed on 194 adult patients without known kidney lesions. Measurements included length, width, cortical thickness and estimation of renal size which was obtained by multiplying the first three variables. The effect of age, gender, side, height, weight, BMI, hypertension and diabetes mellitus was statistically analyzed.

RESULTS

The mean kidney length was 10.4 +/- 0.8 cm, mean with 4.5 +/- 0.6 cm and mean cortical thickness 1.6 +/- 0.2 cm. The estimated mean renal size was 76 +/- 22 cm3. Kidney length did not significantly differ between right and left, however, kidney width, cortical thickness and size did (p < 0.05). Right kidneys were smaller than the left ones. In univariate analysis, the mean renal size correlated with age, sex, side, BMI and absence or presence of hypertension and diabetes mellitus. In a multivariate analysis, however, the only significant factors affecting renal size were sex and BMI.

CONCLUSION

We conclude that renal size is related to age, side, sex and the individual's height and weight. Population-based studies are needed to establish the normal values for the Pakistani population.

Quantitative immunohistochemical detection of oxidized low density lipoprotein in the rabbit arterial wall

Quantitative immunohistochemical techniques were developed for mapping low density lipoprotein (LDL) oxidation within arterial tissue. Antibodies were raised by immunizing rabbits with Cu(2+)-oxidized rabbit LDL. ELISAs showed that they reacted strongly with oxidized rabbit LDL, weakly with other oxidized lipoproteins, and not at all with native LDL. Using optimized histological procedures, the antibodies were applied to sections of calibration gels containing LDL at various concentrations and levels of oxidation, and to sections of aortas from normal and heritable hyperlipidemic rabbits. Binding was measured with a rhodamine-labeled secondary antibody and carefully calibrated techniques of digital imaging fluorescence microscopy. Values obtained using a nonspecific primary antibody were subtracted. Specific binding to calibration sections increased linearly with respect to the concentration of oxidized LDL and the duration of its exposure to Cu2+, approximately linearly with respect to its modified lysine content, and nonlinearly with respect to its relative electrophoretic mobility. Specific staining was detected in sections of aortas from heritable hyperlipidemic but not normal rabbits. In the former, it was higher in the intima than in the media and was greater downstream than upstream of intercostal branch ostia; the average level was lower in those branches with the least intimal thickening but the difference between upstream and downstream regions was larger. These results correlate with the known pattern of lipid deposition in hyperlipidemic rabbit aortas. A small but significant amount of specific staining was observed in sections which were devoid of intimal thickening, which is consistent with LDL oxidation occurring prior to disease or during its earliest stages.

Molecular maturation of cell adhesion systems during mouse early development

During cleavage, the mouse embryo expresses a variety of cell adhesion systems on its cell surfaces. We have reviewed biogenetic and assembly criteria for the formation of the uvomorulin/catenin, tight junction and desmosome adhesion systems as the trophectoderm differentiates. Each system reveals different mechanisms regulating molecular maturation. Adhesion processes contribute to the generation of distinct tissues in the blastocyst by modifying the expression pattern of blastomeres entering the non-epithelial inner cell mass lineage. Cell adhesion also influences the spatial organisation, but rarely the timing of expression, of proteins involved in trophectoderm differentiation.

Biogenesis of structural intercellular junctions during cleavage in the mouse embryo

The preimplantation embryo differentiates the trophectoderm epithelium which, from the 32-cell stage, generates the blastocoel of the blastocyst and, after implantation, gives rise to most extraembryonic lineages of the conceptus. Trophectoderm differentiation begins at compaction (8-cell stage) when cell-cell adhesion, mediated by uvomorulin, and epithelial cell polarisation first occur. Here, we review our work on the biogenesis of tight junctions and desmosomes during epithelial differentiation. Tight junction construction begins at compaction and appears to be a gradual process, both at morphological and molecular levels. This maturation pattern may be due in part to sequential expression of tight junction constituents from the embryonic genome. Tight junction formation is dependent upon uvomorulin adhesion but can be inhibited by different means without apparently disturbing cell adhesion or polarisation. Cell interactions appear to regulate tight junction tissue specificity, in part by controlling the level of synthesis of constituents. Desmosome formation begins at the 32-cell stage, particularly as the embryo initiates blastocoel accumulation, and, in contrast with tight junction formation, does not appear to be a gradual process. Thus, nascent desmosomes appear mature in terms of their molecular composition. Desmosomal proteins are synthesised well in advance of desmosome formation but the synthesis of the principal glycoprotein components begins at the blastocyst stage and may regulate the timing of junction assembly. Implications of these differing patterns of biogenesis for the embryo are discussed.

Tight junction protein cingulin is expressed by maternal and embryonic genomes during early mouse development

The expression of the tight junction peripheral membrane protein, cingulin (140 × 10(3) M(r), was investigated in mouse eggs and staged preimplantation embryos by immunoblotting and immunoprecipitation. Polyclonal antibody to chicken brush cingulin detected a single 140 × 10(3) M(r) protein in immunoblots of unfertilised eggs and all preimplantation stages. Relative protein levels were high in eggs and early cleavage stages, declined during later cleavage and increased again in expanding blastocysts. Quantitative immunoprecipitation of metabolically labelled eggs and staged embryos also revealed a biphasic pattern for cingulin synthesis with relative net levels being high in unfertilised eggs, minimal during early cleavage, rising 2.3-fold specifically at the onset of compaction (8-cell stage, when tight junction formation begins), and increasing further at a linear rate during morula and blastocyst stages. Cingulin synthesis in eggs is not influenced by fertilisation (or aging, if unfertilised), but this level declines sharply after first cleavage. These results indicate that cingulin is expressed by both maternal and embryonic genomes. The turnover of maternal cingulin (unfertilised eggs) and embryonic cingulin at a stage before tight junction formation begins (4-cell stage) is higher (t1/2 approximately 4 hours) than cingulin synthesised after tight junction formation (blastocysts; t1/2 approximately 10 hours). This increase in cingulin stability is reversed in the absence of extracellular calcium. Cingulin synthesis is also tissue-specific in blastocysts, being up-regulated in trophectoderm and down-regulated in the inner cell mass. Taken together, the results suggest that (i) cingulin may have a role during oogenesis and (ii) cell-cell contact patterns regulate cingulin biosynthesis during early morphogenesis, contributing to lineage-specific epithelial maturation.

Localisation of tight junction protein cingulin is temporally and spatially regulated during early mouse development

The molecular maturation of the tight junction in the mouse early embryo has been investigated by monitoring the distribution of cingulin, a 140 × 10(3) M(r) peripheral (cytoplasmic) membrane constituent of the junction, at different stages of development and in different experimental situations. Although tight junction formation does not begin until compaction at the 8-cell stage, cingulin is detectable in oocytes and all stages of cleavage, a factor consistent with our biochemical analysis of cingulin expression (Javed et al., 1992, Development 117, 1145–1151). Using synchronised egg and embryo stages and isolated cell clusters, we have identified three sites where cingulin is localised, the cytocortex, punctate cytoplasmic foci and tight junctions themselves. Cytocortical cingulin is present at the cumulus-oocyte contact site (both cell types), in unfertilised and fertilised eggs and in cleavage stages up to 16-cell morulae, particularly at microvillous domains on the embryo outer surface (eg. apical poles at compaction). Embryo manipulation experiments indicate that cortical cingulin is labile and dependent upon cell interactions and therefore is not merely an inheritance from the egg. Cingulin cytoplasmic foci are evident only in outer cells (prospective trophectoderm) from the 32-cell stage, just prior to cavitation, and decline from approx. 8 hours after cavitation has initiated. The appearance of these foci is insensitive to cycloheximide treatment and they colocalise with apically derived endocytic vesicles visualised by FITC-dextran, indicating that the foci represent the degradation of cytocortical cingulin by endocytic turnover. Cingulin is detectable at the tight junction site between blastomeres usually from the 16-cell stage, although earlier assembly occurs in a minority (up to 20%) of specimens. Cingulin assembly at the tight junction is sensitive to cycloheximide and is identifiable approx. 10 hours after cell adhesion is initiated and ZO-1 protein assembles. Collectively, our results indicate that (i) cingulin from nonjunctional sites does not contribute to tight junction assembly and (ii) the molecular maturation of the junction appears to occur progressively over at least two cell cycles.

Epithelial differentiation and intercellular junction formation in the mouse early embryo

Trophectoderm differentiation during blastocyst formation provides a model for investigating how an epithelium develops in vivo. This paper briefly reviews our current understanding of the stages of differentiation and possible control mechanisms. The maturation of structural intercellular junctions is considered in more detail. Tight junction formation, essential for blastocoele cavitation and vectorial transport activity, begins at compaction (8-cell stage) and appears complete before fluid accumulation begins a day later (approx 32-cell stage). During this period, initial focal junction sites gradually extend laterally to become zonular and acquire the peripheral tight junction proteins ZO-1 and cingulin. Our studies indicate that junction components assemble in a temporal sequence with ZO-1 assembly preceding that of cingulin, suggesting that the junction forms progressively and in the ‘membrane to cytoplasm’ direction. The protein expression characteristics of ZO-1 and cingulin support this model. In contrast to ZO-1, cingulin expression is also detectable during oogenesis where the protein is localised in the cytocortex and in adjacent cumulus cells. However, maternal cingulin is metabolically unstable and does not appear to contribute to later tight junction formation in trophectoderm. Cell-cell interactions are important regulators of the level of synthesis and state of assembly of tight junction proteins, and also control the tissue-specificity of expression. In contrast to the progressive nature of tight junction formation, nascent desmosomes (formed from cavitation) appear mature in terms of their substructure and composition. The rapidity of desmosome assembly appears to be controlled by the time of expression of their transmembrane glycoprotein constitutents; this occurs later than the expression of more cytoplasmic desmosome components and intermediate filaments which would therefore be available for assembly to occur to completion.

Glutamate dehydrogenase (NADP-dependent) mRNA in relation to enzyme synthesis in Euglena gracilis. Evidence for post-transcriptional control

Cells of Euglena gracilis Klebs strain z Pringsheim had high NADP-dependent glutamate dehydrogenase activity when grown on glutamate as nitrogen source but activity was completely repressed in cells grown on ammonium (NH4+). A 120-fold purification of NADPH-glutamate dehydrogenase (subunit Mr = 45 000) was achieved from glutamate-grown cells by affinity chromatography on blue Sepharose CL-6B. Antisera raised against the homogeneously pure protein were used to demonstrate that increase in NADPH-glutamate dehydrogenase activity on transfer from NH4+ to glutamate medium resulted from an increase in the amount of protein. Glutamate NH4+-grown cells were labelled with L-[35S]methionine and anti-(NADPH-glutamate dehydrogenase) used to immunoprecipitate the dehydrogenase from cell extracts. NADPH-glutamate dehydrogenase protein was detected in glutamate-grown but not NH4+-grown cells. Anti-(NADPH-glutamate dehydrogenase) was used to detect NADPH-glutamate dehydrogenase resulting from the translation of total polyadenylated RNA from Euglena in a cell-free rabbit reticulocyte lysate system. NADPH-glutamate dehydrogenase mRNA was present in glutamate NH4+-grown cells, there being no apparent difference in mRNA abundance between cells showing a tenfold difference in NADPH-glutamate dehydrogenase specific activity. These results indicate that the synthesis of this dehydrogenase is regulated primarily at the post-transcriptional level.

EFFECT OF GROWTH CONDITIONS ON NADPH-SPECIFIC GLUTAMATE DEHYDROGENASE ACTIVITY OF EUGLENA GRACILIS

Cells of Euglena gracilis Klebs, strain z Pringsheim, had high NADPH-glutamate dehydrogenase (GDH) activity when grown on glutamate but activity was repressed completely in cells grown on ammonium (NH₄ ⁺ ). Subcellular fractionation showed that NADPH-GDH activity was located exclusively in the cytosol, while glutamine synthetase was present in the cytosol and chloroplasts. Despite high NADPH-GDH activity NH₄ ⁺ assimilation was completely inhibited by methionine sulphoximine (MSO), an inhibitor of glutamine synthetase. With MSO present, cells produced NH₄ ⁺ and it was shown that greatest NH₄ ⁺ production occurred with cells containing high levels of NADPH-GDH activity and plentiful carbon supply. It is concluded that NADPH-GDH has a catabolic function in Euglena generating NH₄ ⁺ from glutamate under conditions of nitrogen limitation.