Elucidation of the molecular mechanism and the efficacy in vivo of a novel 1,4-benzoquinone that inhibits 5-lipoxygenase

BACKGROUND AND PURPOSE

1,4-Benzoquinones are well-known inhibitors of 5-lipoxygenase (5-LOX, the key enzyme in leukotriene biosynthesis), but the molecular mechanisms of 5-LOX inhibition are not completely understood. Here we investigated the molecular mode of action and the pharmacological profile of the novel 1,4-benzoquinone derivative 3-((decahydronaphthalen-6-yl)methyl)-2,5-dihydroxycyclohexa-2,5-diene-1,4-dione (RF-Id) in vitro and its effectiveness in vivo.

EXPERIMENTAL APPROACH

Mechanistic investigations in cell-free assays using 5-LOX and other enzymes associated with eicosanoid biosynthesis were conducted, along with cell-based studies in human leukocytes and whole blood. Molecular docking of RF-Id into the 5-LOX structure was performed to illustrate molecular interference with 5-LOX. The effectiveness of RF-Id in vivo was also evaluated in two murine models of inflammation.

KEY RESULTS

RF-Id consistently suppressed 5-LOX product synthesis in human leukocytes and human whole blood. RF-Id also blocked COX-2 activity but did not significantly inhibit COX-1, microsomal PGE2 synthase-1, cytosolic PLA2 or 12- and 15-LOX. Although RF-Id lacked radical scavenging activity, reducing conditions facilitated its inhibitory effect on 5-LOX whereas cell stress impaired its efficacy. The reduced hydroquinone form of RF-Id (RED-RF-Id) was a more potent inhibitor of 5-LOX as it had more bidirectional hydrogen bonds within the 5-LOX substrate binding site. Finally, RF-Id had marked anti-inflammatory effects in mice in vivo.

CONCLUSIONS AND IMPLICATIONS

RF-Id represents a novel anti-inflammatory 1,4-benzoquinone that potently suppresses LT biosynthesis by direct inhibition of 5-LOX with effectiveness in vivo. Mechanistically, RF-Id inhibits 5-LOX in a non-redox manner by forming discrete molecular interactions within the active site of 5-LOX.

Natural compounds in anti-leukaemic therapy: a review

Human leukemia results from multiple mutations that lead to abnormalities in the expressions and functions of genes that maintain the delicate balance between proliferation, differentiation and apoptosis. Continued research on the molecular aspects of leukemia cells has resulted in the developments of several potentially useful therapeutic agents. Discovery of new cellular and/or molecular pathways enabling innate or acquired resistance of cancers to current chemotherapeutics to be overcome is therefore of crucial importance if one wants to efficiently combat those cancers associated with dismal prognoses. In this concern, natural compounds are regarded as new chemical entities for the development of drugs against various pharmacological targets, including cancer, and, above all, leukemia.

Increased detections of leptomeningeal presentations in men with hormone refractory prostate cancer: an effect of improved systemic therapy?

Metastases from prostate cancer occur largely in bone through a haematogenous route. Metastatic spread of prostate cancer to the leptomeninges was rarely seen in the past. However, there has been a recent increase in presentations of leptomeningeal spread from prostate cancer in our institutions. Between 2004 and 2006, four patients were diagnosed with metastatic prostate cancer with leptomeningeal metastases in our centres. All four patients had hormone refractory prostate cancer and had previously had chemotherapy. The median survival of these patients was approximately 15 months from the time of hormone refractoriness. The prognosis of leptomeningeal metastasis secondary to metastatic prostate cancer is poor, ranging from 2 to 7 months as seen in our series. New cases of leptomeningeal metastases seen in our series are hypothesized to be secondary to the use of effective modern systemic treatments. A parallel might be drawn with the increased rate of central nervous system metastases in breast cancer since the introduction of effective cytotoxic treatments and more recently targeted therapies. We suggest the clinicians to be aware of the potential change of natural history and pattern of progression in metastatic prostate cancer.

Dissociative responses to conscious and non-conscious fear impact underlying brain function in post-traumatic stress disorder

BACKGROUND

Dissociative reactions in post-traumatic stress disorder (PTSD) have been regarded as strategic responses that limit arousal. Neuroimaging studies suggest distinct prefrontal responses in individuals displaying dissociative and hyperarousal responses to threat in PTSD. Increased prefrontal activity may reflect enhanced regulation of limbic arousal networks in dissociation. If dissociation is a higher-order regulatory response to threat, there may be differential responses to conscious and automatic processing of threat stimuli. This study addresses this question by examining the impact of dissociation on fear processing at different levels of awareness.

METHOD

Functional magnetic resonance imaging (fMRI) with a 1.5-T scanner was used to examine activation to fearful (versus neutral) facial expressions during consciously attended and non-conscious (using backward masking) conditions in 23 individuals with PTSD. Activation in 11 individuals displaying non-dissociative reactions was compared to activation in 12 displaying dissociative reactions to consciously and non-consciously perceived fear stimuli.

RESULTS

Dissociative PTSD was associated with enhanced activation in the ventral prefrontal cortex for conscious fear, and in the bilateral amygdala, insula and left thalamus for non-conscious fear compared to non-dissociative PTSD. Comparatively reduced activation in the dissociative group was apparent in dorsomedial prefrontal regions for conscious fear faces.

CONCLUSIONS

These findings confirm our hypotheses of enhanced prefrontal activity to conscious fear and enhanced activity in limbic networks to non-conscious fear in dissociative PTSD. This supports the theory that dissociation is a regulatory strategy invoked to cope with extreme arousal in PTSD, but this strategy appears to function only during conscious processing of threat.

Amygdala and ventral anterior cingulate activation predicts treatment response to cognitive behaviour therapy for post-traumatic stress disorder

BACKGROUND

Although cognitive behaviour therapy (CBT) is the treatment of choice for post-traumatic stress disorder (PTSD), approximately half of patients do not respond to CBT. No studies have investigated the capacity for neural responses during fear processing to predict treatment response in PTSD.

METHOD

Functional magnetic resonance imaging (fMRI) responses of the brain were examined in individuals with PTSD (n=14). fMRI was examined in response to fearful and neutral facial expressions presented rapidly in a backwards masking paradigm adapted for a 1.5 T scanner. Patients then received eight sessions of CBT that comprised education, imaginal and in vivo exposure, and cognitive therapy. Treatment response was assessed 6 months after therapy completion.

RESULTS

Seven patients were treatment responders (defined as a reduction of 50% of pretreatment scores) and seven were non-responders. Poor improvement after treatment was associated with greater bilateral amygdala and ventral anterior cingulate activation in response to masked fearful faces.

CONCLUSIONS

Excessive fear responses in response to fear-eliciting stimuli may be a key factor in limiting responses to CBT for PTSD. This excessive amygdala response to fear may reflect difficulty in managing anxiety reactions elicited during CBT, and this factor may limit optimal response to therapy.

[Mycoplasma pneumoniae is not a respiratory pathogen only: two case reports of ''atypical'' clinical presentations]

Mycoplasma pneumoniae is a common intracellular pathogen, which is responsible for infections of the respiratory tract, particularly in patients between 5 and 30 years of age. Nevertheless, there is increasing evidence that Mycoplasma pneumoniae plays a role in determining clinical presentations different from the respiratory ones. Among extra pulmonary complications skin eruptions are more frequent than others, even with severe clinical features such as Stevens Johnson syndrome. It is important to note that dermatological involvement can occur before, during or after the appearance of respiratory symptoms or without them. We report two patients whose onset of symptoms was not a respiratory tract disease, as usual in Mycoplasma pneumoniae infections, but prolonged and high grade fever with a relevant skin involvement pointing out the importance of researching Mycoplasma pneumoniae in the pathogenesis of peculiar clinical features. The first patient is a 4-year-old boy with signs of Stevens Johnson syndrome while the second patient is a 16-year-old girl with red-purple maculae on both legs and arms; in both cases we detected Mycoplasma IgM antibodies as a part of differential diagnosis. We discuss below the immunological mechanism by which Mycoplasma pneumoniae can determine the clinical features shown by our patients.

An unusual clinical and biochemical presentation of ornithine transcarbamylase deficiency in a male patient

We report a male patient with a history of recurrent idiopathic vomiting, normal plasma ammonia and glutamine concentrations in acute phase, who died at 3 years of age. Ornithine transcarbamylase deficiency was diagnosed after detecting elevated urinary orotate concentrations in a sample collected just before death, and the diagnosis was confirmed by DNA analysis.

A novel mutation in the GLUT2 gene in a patient with Fanconi-Bickel syndrome detected by neonatal screening for galactosaemia

A patient affected by Fanconi-Bickel syndrome detected by neonatal screening for galactosaemia is reported. Molecular studies of the GLUT2 gene led to the identification of a novel mutation of the glucose transporter.

Arousal dissociates amygdala and hippocampal fear responses: evidence from simultaneous fMRI and skin conductance recording

The experience and appraisal of threat is essential to human and animal survival. Lesion evidence suggests that the subjective experience of fear relies upon amygdala-medial frontal activity (as well as autonomic arousal), whereas the factual context of threat stimuli depends upon hippocampal-lateral frontal activity. This amygdala-hippocampus dissociation has not previously been demonstrated in vivo. To explore this differentiation, we employed functional magnetic resonance imaging (fMRI) and simultaneous skin conductance response (SCR) measures of phasic arousal, while subjects viewed fearful versus neutral faces. fMRI activity was subaveraged according to whether or not the subject evoked an arousal SCR to each discrete face stimulus. The fMRI-with arousal and fMRI-without arousal data provided a distinct differentiation of amygdala and hippocampal networks. Amygdala-medial frontal activity was observed only with SCRs, whereas hippocampus-lateral frontal activity occurred only in the absence of SCRs. The findings provide direct evidence for a dissociation between human amygdala and hippocampus networks in the visceral experience versus declarative fact processing of fear.

Splenosis mimicking metastases from breast carcinoma

The case history is presented of a patient with breast cancer who was extensively investigated for presumed hepatic metastases, which were finally diagnosed as splenosis, the heterotopic autotransplantation of splenic tissue after traumatic rupture of the spleen. This case history highlights the importance of obtaining a pathological diagnosis prior to labelling a patient as having metastatic disease. This is especially important for patients who have an unusual pattern or appearance of metastases or for whom the risk of metastatic disease is presumed to be minimal.

Autonomic neuropathy in liver cirrhosis: relationship with alcoholic aetiology and severity of the disease

Autonomic neuropathy has been frequently observed in alcohol-addicts both with and without liver disease but few data are available on non-alcoholic cirrhotics. We studied the prevalence of this disorder in 113 cirrhotics (41 alcoholics and 72 non-alcoholics) to correlate it both with residual liver efficiency and the aetiology of liver cirrhosis. We used 5 cardio-vascular tests commonly adopted to assess the parasympathetic [Valsalva manoeuvre (VR), deep breathing (DB), lying-to-standing (LS)] and sympathetic function [sustained handgrip (SH) and orthostatic hypotension (OH)]. Results obtained indicate that: a) autonomic neuropathy was observed in 60% of the patients (71% in alcoholic and 57% in non-alcoholic cirrhosis; p < 0.01); b) the alterations of the parasympathetic function are significantly more frequent than those of the sympathetic function; c) DB and SH tests seem to be influenced by the compliance of the patient; DB was the most altered test and LS was the most specific and sensitive test; d) a simplified series of three diagnostic tests (2 parasympathetic: VR and LS, plus a sympathetic one: HO) is as accurate for the diagnosis as the combination of the 5 tests.

Alterations of vibratory and thermal peripheral sensitivity in liver cirrhosis

Peripheral neurological involvement, causing distal paresthesias and/or cramps has been described in liver cirrhosis, and its symptoms are quite frequent in decompensated patients under diuretic treatment. In this paper we reported thermal (TPT) and vibratory (VPT) sensations in 100 well-defined cirrhotics (43 in group A, and 63 in B and C of Child-Pugh classification) to define the prevalence of such alterations and the role of sex, age, severity and aetiology of the cirrhosis, and diuretic treatment. The TPT and VPT values were out of the normal range in 28% and 39% of the patients, respectively. Significantly, the alteration of VPT was associated both to alcoholic aetiology and decompensated cirrhosis, whereas the only parameter significantly associated to TPT alterations was alcoholic aetiology. Multiple factors such as inappropriate nutrition, hypercatabolic status, and portal systemic shunting may play a role in inducing trophic disturbances of nervous fibres in cirrhotics.

Decision-making model for a non-invasive diagnosis of compensated liver cirrhosis

Liver biopsy is used as a gold standard in the diagnosis of chronic liver disease. However, this procedure is not without risk to the patients. This study was aimed to evaluate whether clinical, ultrasonographic, and biochemical variables may discriminate between well-compensated liver cirrhosis and non-cirrhotic chronic liver disease. Logistic regression analysis was used to assess the independent predictive value of each variable. Moreover, the post-test probability of the diagnostic variables was converted into "weights" which positively correlated with the likelihood of diagnosis of liver cirrhosis. We applied a decisional rule based on the diagnostic "weight" of each variable to 412 patients, 278 with well-compensated liver cirrhosis and 134 with non-cirrhotic chronic liver disease, diagnosed by liver biopsy with/without laparoscopy. By adding the diagnostic "weights" of each variable, liver cirrhosis and non-cirrhotic chronic liver disease were correctly diagnosed in 67% and 75% of cases, respectively. This result was validated in a split sample of 100 patients (50 with compensated liver cirrhosis and 50 with non-cirrhotic chronic liver disease) randomly selected from the acquisition sample. Based on this data, diagnosis of well-compensated liver cirrhosis can be reached in over 67% of cases without using invasive procedures. However, a prospective study is needed to confirm the clinical reliability of this method.