Echotexture of peripheral nerves: correlation between US and histologic findings and criteria to differentiate tendons

PURPOSE

To correlate the histologic structure and echotexture of peripheral nerves and verify if ultrasound (US) findings can be used to differentiate nerve from tendon.

MATERIALS AND METHODS

In an in vitro study, the echotexture of normal peripheral nerves was correlated with the histologic findings. In an in vivo study, US was used to differentiate median nerve from flexor pollicis longus tendon in healthy volunteers (12 male and eight female subjects 7-68 years of age; mean age, 35 years).

RESULTS

US examination of the peripheral nerve specimens showed hypoechoic areas separated by hyperechoic bands. The hypoechoic areas corresponded to neuronal fascicles at histologic examination. This fascicular pattern was clear in all median and ulnar nerves, 15 of 20 vagus nerves, and 19 of 20 sciatic nerves in the volunteers but not in recurrent laryngeal nerves.

CONCLUSION

Peripheral nerves have a typical US pattern that correlates with histologic structure and facilitates differentiation between nerves and tendons.

Analysis of echotexture of tendons with US

To evaluate changes in echotexture of normal tendons at different frequencies and establish an anatomic correlation for fibrillar echoes, normal calcaneal tendons were examined in vitro at 7.5, 10, 13, and 15 MHz in calves (n = 8) and sheep (n = 6) and in vivo in humans (n = 8). Histologic correlation was obtained in vitro with 22-gauge needles that marked the position of echogenic fibrils under ultrasound (US) guidance. The human study group consisted of 25 patients with a clinical diagnosis of calcaneal tendon disease and 15 patients who underwent surgery for rupture of the Achilles tendon. At all four frequencies, normal tendons showed an internal network of fine parallel and linear fibrillar echoes that became more numerous and thinner as US frequency increased. These echoes were caused by specular reflections at the interface between collagen bundles and endotendineum septa. In patients, tendons showed a variety of basic changes in fibrillar pattern: increased fibrillar thickness (33 patients), interruption (17 patients), fragmentation (12 patients), and disappearance of echotexture (15 patients). It is concluded that US holds promise in detection of minimal changes in tendinous structure.

Dietary zinc supplementation of 3xTg-AD mice increases BDNF levels and prevents cognitive deficits as well as mitochondrial dysfunction

The overall effect of brain zinc (Zn²⁺) in the progression and development of Alzheimer's disease (AD) is still not completely understood. Although an excess of Zn²⁺ can exacerbate the pathological features of AD, a deficit of Zn²⁺ intake has also been shown to increase the volume of amyloid plaques in AD transgenic mice. In this study, we investigated the effect of dietary Zn²⁺ supplementation (30 p.p.m.) in a transgenic mouse model of AD, the 3xTg-AD, that expresses both β amyloid (Aβ)- and tau-dependent pathology. We found that Zn²⁺ supplementation greatly delays hippocampal-dependent memory deficits and strongly reduces both Aβ and tau pathology in the hippocampus. We also evaluated signs of mitochondrial dysfunction and found that Zn²⁺ supplementation prevents the age-dependent respiratory deficits we observed in untreated 3xTg-AD mice. Finally, we found that Zn²⁺ supplementation greatly increases the levels of brain-derived neurotrophic factor (BDNF) of treated 3xTg-AD mice. In summary, our data support the idea that controlling the brain Zn²⁺ homeostasis may be beneficial in the treatment of AD.

Color Doppler sonography of salivary glands

OBJECTIVE

We used color Doppler sonography to evaluate the vascular anatomy of the salivary glands and to analyze physiologic changes that occur during salivary stimulation in normal subjects and the flow alterations that occur in diseased glands.

SUBJECTS AND METHODS

The vascular appearance of the three major salivary glands was examined in healthy volunteers (n = 24); in patients with chronic autoimmune diseases, including Sjögren's syndrome (n = 23) and salivary sarcoidosis (n = 2); and in a variety of benign (n = 49) and malignant (n = 13) nodules. Physiologic changes were assessed in healthy volunteers by means of a stimulation test with lemon and were quantified with color images and spectral analysis. Tumor vascularity was graded on a four-step analog scale of 0 to (+3) and classified as either peripheral or hilar, depending on the distribution of vessels.

RESULTS

In the control subjects, color Doppler imaging accurately reflected the complex vascular anatomy of the salivary glands and showed dramatic changes occurring in parenchymal vessels during lemon stimulation as a result of the intense hyperemia associated with the secretion of saliva. Sjögren's syndrome and sarcoidosis showed a diffuse hypervascular pattern when morphologic changes of salivary parenchyma were seen on gray-scale sonograms. Benign tumors showed a lower grade of vascularity than did malignant tumors. All but one of the hypovascular nodules graded as 0 (n = 8) and + (n = 23) were benign. Conversely, eight of 11 nodules labeled with the highest grade of tumor vascularity (+3) were malignant. When the pattern of tumor flow signals was peripheral, it could be considered specific enough to aid in diagnosing pleomorphic adenoma. Peak systolic velocities greater than 60 cm/sec were never detected in benign tumors and were seen in only 44% of malignant tumors.

CONCLUSION

Color Doppler sonography is a promising technique for analyzing the vascularity of the salivary glands and for characterizing some pathologic conditions. Our experience suggests that color Doppler sonography can provide additional diagnostic information in patients with chronic inflammatory diseases or suspected malignant tumors and can help in differentiating pleomorphic adenomas from other salivary gland tumors.

Uncoupling protein-3 is a molecular determinant for the regulation of resting metabolic rate by thyroid hormone

Thyroid hormones increase energy expenditure, partly by reducing metabolic efficiency. The control of specific genes at the transcriptional level is thought to be the major molecular mechanism. However, both the number and the identity of the thyroid hormone-controlled genes remain unknown, as do their relative contributions. Uncoupling protein-3, a recently identified member of the mitochondrial transporter superfamily and one that is predominantly expressed in skeletal muscle, has the potential to be a molecular determinant for thyroid thermogenesis. However, changes in mitochondrial proton conductance and resting metabolic rate after physiologically mediated changes in uncoupling protein-3 levels have not been described. Here, in a study on hypothyroid rats given a single injection of T(3), we describe a strict correlation in terms of time course between the induced increase in uncoupling protein-3 expression (at mRNA and protein levels) and decrease in mitochondrial respiratory efficiency, on the one hand, and the increase in resting metabolic rate, on the other. First, we describe our finding that uncoupling protein-3 is present and regulated by T(3) only in metabolically relevant tissues (such as skeletal muscle and heart). Second, we follow the time course (at 0, 6, 12, 24, 48, 65, 96, and 144 h) of both uncoupling protein-3 mRNA levels and mitochondrial uncoupling protein-3 density in gastrocnemius muscle and heart. In both tissues, the maximal (12-fold) increase in uncoupling protein-3 density was reached at 65 h. The resting metabolic rate [lO(2)(kg(0.75))(-1)h(-1)] showed the same time course, and at 65 h the increase vs. time zero was 45% (1.316 +/- 0.026 vs. 0.940 +/- 0.007; P < 0.001). At the same time point, gastrocnemius muscle mitochondria showed a significantly higher nonphosphorylating respiration rate (nanoatoms of oxygen per min/mg protein; increase vs. time zero, 40%; 118 +/- 4 vs. 85 +/- 9; P < 0.05), whereas the membrane potential decreased by 8% (168 +/- 2 vs. 182 +/- 4; P < 0.05). These data are diagnostic of mitochondrial uncoupling. The results reported here provide the first direct in vivo evidence that uncoupling protein-3 has the potential to act as a molecular determinant in the regulation of resting metabolic rate by T(3).

Defining the transcriptomic and proteomic profiles of rat ageing skeletal muscle by the use of a cDNA array, 2D- and Blue native-PAGE approach

We defined the transcriptomic and proteomic profiles of rat ageing skeletal muscle using a combined cDNA array, 2D- and Blue native-PAGE approach. This was allowed to obtain an overview of the interrelated events leading to the transcriptome/proteome/mitoproteome changes likely to underlie the structural/metabolic features of aged skeletal muscle. The main differences were found in genes/proteins related to energy metabolism, mitochondrial pathways, myofibrillar filaments, and detoxification. Concerning the abundance of mitochondrial OXPHOS complexes as well as their supramolecular organization and activity, mitochondria from old rats, when compared with those from young rats, contained significantly lower amounts of complex I (NADH:ubiquinone oxidoreductase), V (FoF1-ATP synthase), and III (ubiquinol:cytochrome c oxidoreductase). The same mitochondria contained a significantly larger amount of complex II (succinate:ubiquinone oxidoreductase), but an unchanged amount of complex IV (cytochrome c oxidase, COX). When comparing the supercomplex profiles between young and old muscle mitochondria, the densitometric analysis revealed that lighter supercomplexes were significantly reduced in older mitochondria, and that in the older group the major supercomplex bands were those representing heavier supercomplexes, likely suggesting a compensatory mechanism that, in ageing muscle, is functionally directed towards substrate channeling and catalytic enhancement advantaging the respirosome.

3,5-Diiodo-L-thyronine rapidly enhances mitochondrial fatty acid oxidation rate and thermogenesis in rat skeletal muscle: AMP-activated protein kinase involvement

Triiodothyronine regulates energy metabolism and thermogenesis. Among triiodothyronine derivatives, 3,5-diiodo-l-thyronine (T(2)) has been shown to exert marked effects on energy metabolism by acting mainly at the mitochondrial level. Here we investigated the capacity of T(2) to affect both skeletal muscle mitochondrial substrate oxidation and thermogenesis within 1 h after its injection into hypothyroid rats. Administration of T(2) induced an increase in mitochondrial oxidation when palmitoyl-CoA (+104%), palmitoylcarnitine (+80%), or succinate (+30%) was used as substrate, but it had no effect when pyruvate was used. T(2) was able to 1) activate the AMPK-ACC-malonyl-CoA metabolic signaling pathway known to direct lipid partitioning toward oxidation and 2) increase the importing of fatty acids into the mitochondrion. These results suggest that T(2) stimulates mitochondrial fatty acid oxidation by activating several metabolic pathways, such as the fatty acid import/beta-oxidation cycle/FADH(2)-linked respiratory pathways, where fatty acids are imported. T(2) also enhanced skeletal muscle mitochondrial thermogenesis by activating pathways involved in the dissipation of the proton-motive force not associated with ATP synthesis ("proton leak"), the effect being dependent on the presence of free fatty acids inside mitochondria. We conclude that skeletal muscle is a target for T(2), and we propose that, by activating processes able to enhance mitochondrial fatty acid oxidation and thermogenesis, T(2) could play a role in protecting skeletal muscle against excessive intramyocellular lipid storage, possibly allowing it to avoid functional disorders.

Thyroid hormones as molecular determinants of thermogenesis

Thyroid hormones (TH) are major modulators of energy metabolism and thermogenesis. It is generally believed that 3,5,3'-triiodo-l-thyronine (T3) is the only active form of TH, and that most of its effects are mediated by nuclear T3 receptors, which chiefly affect the transcription of target genes. Some of these genes encode for the proteins involved in energy metabolism. However, a growing volume of evidence now indicates that other iodothyronines may be biologically active. Several mechanisms have been proposed to explain the calorigenic effect of TH, but none has received universal acceptance. Cold acclimation/exposure and altered nutritional status are physiological conditions in which a modulation of energy expenditure is particularly important. TH seem to be deeply involved in this modulation, and this article will review some aspects of their possible influence in these conditions.

Exenatide promotes cognitive enhancement and positive brain metabolic changes in PS1-KI mice but has no effects in 3xTg-AD animals

Recent studies have shown that type 2 diabetes mellitus (T2DM) is a risk factor for cognitive dysfunction or dementia. Insulin resistance is often associated with T2DM and can induce defective insulin signaling in the central nervous system as well as increase the risk of cognitive impairment in the elderly. Glucagone like peptide-1 (GLP-1) is an incretin hormone and, like GLP-1 analogs, stimulates insulin secretion and has been employed in the treatment of T2DM. GLP-1 and GLP-1 analogs also enhance synaptic plasticity and counteract cognitive deficits in mouse models of neuronal dysfunction and/or degeneration. In this study, we investigated the potential neuroprotective effects of long-term treatment with exenatide, a GLP-1 analog, in two animal models of neuronal dysfunction: the PS1-KI and 3xTg-AD mice. We found that exenatide promoted beneficial effects on short- and long-term memory performances in PS1-KI but not in 3xTg-AD animals. In PS1-KI mice, the drug increased brain lactate dehydrogenase activity leading to a net increase in lactate levels, while no effects were observed on mitochondrial respiration. On the contrary, exenatide had no effects on brain metabolism of 3xTg-AD mice. In summary, our data indicate that exenatide improves cognition in PS1-KI mice, an effect likely driven by increasing the brain anaerobic glycolysis rate.

Effects of long-term treatment with pioglitazone on cognition and glucose metabolism of PS1-KI, 3xTg-AD, and wild-type mice

In this study, we investigated the effects of long-term (9-month) treatment with pioglitazone (PIO; 20 mg/kg/d) in two animal models of Alzheimer's disease (AD)-related neural dysfunction and pathology: the PS1-KI(M146V) (human presenilin-1 (M146V) knock-in mouse) and 3xTg-AD (triple transgenic mouse carrying AD-linked mutations) mice. We also investigated the effects on wild-type (WT) mice. Mice were monitored for body mass changes, fasting glycemia, glucose tolerance, and studied for changes in brain mitochondrial enzyme activity (complexes I and IV) as well as energy metabolism (lactate dehydrogenase (LDH)). Cognitive effects were investigated with the Morris water maze (MWM) test and the object recognition task (ORT). Behavioral analysis revealed that PIO treatment promoted positive cognitive effects in PS1-KI female mice. These effects were associated with normalization of peripheral gluco-regulatory abnormalities that were found in untreated PS1-KI females. PIO-treated PS1-KI females also showed no statistically significant alterations in brain mitochondrial enzyme activity but significantly increased reverse LDH activity.PIO treatment produced no effects on cognition, glucose metabolism, or mitochondrial functioning in 3xTg-AD mice. Finally, PIO treatment promoted enhanced short-term memory performance in WT male mice, a group that did not show deregulation of glucose metabolism but that showed decreased activity of complex I in hippocampal and cortical mitochondria. Overall, these results indicate metabolically driven cognitive-enhancing effects of PIO that are differentially gender-related among specific genotypes.

Normal prostate gland: examination with color Doppler US

PURPOSE

To evaluate the vascular anatomy of the prostate gland with transrectal color Doppler ultrasound (US).

MATERIALS AND METHODS

Thirty-five normal prostate glands were studied. Imaging findings were interpreted on the basis of findings from previous anatomic studies.

RESULTS

Distribution of flow signals within the gland was differentiated into two parenchymal groups of arteries, urethral and capsular. The urethral group entered the prostate at the bladder neck and sent forth branches to supply the periurethral zone and the inner portion of the gland. The capsular group coursed along the anterolateral surface of the prostate and sent forth perforating branches to the outer portion of the gland. Intraprostatic venous signals were seen mainly within the periurethral zone.

CONCLUSION

Transrectal color Doppler US can depict the vascular anatomy of the prostate gland. Knowledge of the normal vascular appearance of the gland should aid in the differentiation of normal from abnormal findings.

Alterations of brain and cerebellar proteomes linked to Aβ and tau pathology in a female triple-transgenic murine model of Alzheimer's disease

The triple-transgenic Alzheimer (3 × Tg-AD) mouse expresses mutant PS1(M146V), APP(swe), and tau(P301L) transgenes and progressively develops plaques and neurofibrillary tangles with a temporal- and region-specific profile that resembles the neuropathological progression of Alzheimer's disease (AD). In this study, we used proteomic approaches such as two-dimensional gel electrophoresis and mass spectrometry to investigate the alterations in protein expression occurring in the brain and cerebellum of 3 × Tg-AD and presenilin-1 (PS1) knock-in mice (animals that do not develop Aβ- or tau-dependent pathology nor cognitive decline and were used as control). Finally, using the Ingenuity Pathway Analysis we evaluated novel networks and molecular pathways involved in this AD model. We identified several differentially expressed spots and analysis of 3 × Tg-AD brains showed a significant downregulation of synaptic proteins that are involved in neurotransmitter synthesis, storage and release, as well as a set of proteins that are associated with cytoskeleton assembly and energy metabolism. Interestingly, in the cerebellum, a structure not affected by AD, we found an upregulation of proteins involved in carbohydrate metabolism and protein catabolism. Our findings help to unravel the pathogenic brain mechanisms set in motion by mutant amyloid precursor protein (APP) and hyperphosphorylated tau. These data also reveal cerebellar pathways that may be important to counteract the pathogenic actions of Aβ and tau, and ultimately offer novel targets for therapeutic intervention.

Topical promethazine side effects: our experience and review of the literature

Promethazine hydrochloride is a first-generation H1 receptor antagonist, antihistamine, and antiemetic medication that can also have strong sedative effects. The apparent ability of topical H1r/2r antagonists to target epidermal H1/2r was translated into increased efficacy in the treatment of inflammatory dermatoses, likely due to decreased inflammation and enhanced barrier function.

Changes in bioimpedance analysis after stable refeeding of undernourished anorexic patients

OBJECTIVE

To evaluate bioimpedance analysis (BIA) parameters in patients with anorexia nervosa when undernourished and then after stable refeeding.

DESIGN

Follow-up study.

SUBJECTS

Thirteen patients with anorexia nervosa who were studied when undernourished (body weight (Wt): 36.9+/-5.6kg, body mass index (BMI): 14.8+/-1.8kg/m2) and after stable refeeding (Wt: 52.9+/-7.1kg, BMI: 21.2+/-2.3 kg/m2) compared to 25 well-nourished control women (Wt: 53.7+/-4.9 kg, BMI: 21.1+/-1.3 kg/m2).

MEASUREMENTS

Impedance and phase angle were determined for the whole body (13 patients) and separately for arms and legs (10 patients).

RESULTS

Bioimpedance index (height2/impedance) and phase angle were lower in the undernourished group. Whole-body impedance declined (median, min-max) by 45, 1-151 Ohm after refeeding; the variations of bioimpedance index (BI-Index) were weakly correlated (P < 0.10) with BMI changes. Limb phase angles increased with refeeding, but only changes in whole-body phase angle were correlated (P < 0.025) with the corresponding variations of Wt or BMI.

CONCLUSION

Whole-body phase angle increased after weight recovery of anorexic patients, suggesting the occurence of modifications in the extracellular-to-intracellular water ratio. These changes were proportional to the increase in BMI and Wt.

Staging of hilar cholangiocarcinoma with ultrasound

The preoperative assessment of the extent of biliary and vascular involvement by hilar cholangiocarcinoma is clinically important because resectability may be limited by tumor extension along the bile ducts into the hepatic parenchyma or to the adjacent hilar vessels. Thirty-five patients with hilar cholangiocarcinoma were studied with ultrasound, and the results were compared with operative findings and other diagnostic modalities. The level of intrahepatic biliary obstruction was determined in 100% of patients with ductal ectasia, and a tumor mass was shown in 37.1%. Imaging and Doppler ultrasound proved accurate in detecting the neoplastic involvement of the portal vein. Both correctly diagnosed portal occlusion and wall infiltration in 4 of 4 and 15 of 18 (83%) patients, respectively, without any false-positives. On the contrary, imaging ultrasound had poor sensitivity in detecting infiltration of the hepatic artery (43%) and metastases in regional lymph nodes (37%), liver (66%), and peritoneum (33%). In conclusion, ultrasound may be valuable in the preoperative staging of hilar cholangiocarcinoma, specially in predicting ductal and portal involvement.

Behçet's syndrome as a tool to dissect the mechanisms of thrombo-inflammation: clinical and pathogenetic aspects

Behçet's syndrome (BS) is a complex disease with different organ involvement. The vascular one is the most intriguing, considering the existence of a specific group of patients suffering from recurrent vascular events involving the venous and, more rarely, the arterial vessels. Several clinical clues suggest the inflammatory nature of thrombosis in BS, especially of the venous involvement, thus BS is considered a model of inflammation-induced thrombosis. Unique among other inflammatory conditions, venous involvement (together with the arterial one) is currently treated with immunosuppressants, rather than with anti-coagulants. Although many in-vitro studies have suggested the different roles of the multiple players involved in clot formation, in-vivo models are crucial to study this process in a physiological context. At present, no clear mechanisms describing the pathophysiology of thrombo-inflammation in BS exist. Recently, we focused our attention on BS patients as a human in-vivo model of inflammation-induced thrombosis to investigate a new mechanism of clot formation. Indeed, fibrinogen displays a critical role not only in inflammatory processes, but also in clot formation, both in the fibrin network and in platelet aggregation. Reactive oxygen species (ROS)-derived modifications represent the main post-translational fibrinogen alterations responsible for structural and functional changes. Recent data have revealed that neutrophils (pivotal in the pathogenetic mechanisms leading to BS damage) promote fibrinogen oxidation and thrombus formation in BS. Altogether, these new findings may help understand the pathogenetic bases of inflammation-induced thrombosis and, more importantly, may suggest potential targets for innovative therapeutic approaches.

The anterior tilt of the acromion: radiographic evaluation and correlation with shoulder diseases

The aim of this study was to test whether the anterior tilt of the acromion can be objectively evaluated on lateral radiographs, and whether there is a relation between this anatomical feature and the most common shoulder diseases. Lateral radiographs of 15 dried scapulas were performed in neutral position and with 5 degrees of caudal, cranial, anterior and posterior angulations. Two hundred and forty-three shoulders, both asymptomatic and affected by chronic and post-traumatic impingement, calcific tendinitis and instability, were examined by conventional radiography. The presence of rotator-cuff tears was investigated by sonography. A method was elaborated to obtain reproducible lateral radiographs and to determine the acromial tilt angle. Inter- and intraobserver and inter- and intraoperator variations in measurements were evaluated. Variations in tube angulation produced changes in tilt-angle values on dried scapulas. The average tilt angle for the chronic impingement and the instability groups were significantly different from the post-traumatic, calcific tendinitis and control groups. Rotator-cuff tears were significantly more frequent in the chronic impingement group and related to a more acute tilt angle. The inter- and intraobserver variability coefficients were 0.95 and 0.98, whereas the inter- and intraoperator variability coefficients were 0.94 and 0.96, respectively. Conventional radiography using fluoroscopy for positioning is a well-reproducible method for the evaluation of acromial tilt. There is a significant difference in tilt-angle values between some groups of subjects examined, but the lack of specificity limits the clinical importance of such measurement.

Thyroid carcinoma mimicking a toxic adenoma

A young woman with a thyroid papillary carcinoma behaving as an autonomously hyperfunctioning nodule is described. Only 17 similar patients have been seen in the past 25 years. It is emphasized that hyperthyroidism does not exclude malignant disease in hot nodules. This possibility suggests that all thyroid nodules, either cold or hot, require careful management. Therefore, in "at risk" cases, surgery could be the most useful treatment.

c-FLIP efficiently rescues TRAF-2-/- cells from TNF-induced apoptosis

For the past 20 years, it has been known that preparations of Tumor Necrosis Factor alpha (TNF) fail to induce apoptosis due to cytoprotective responses that render cells resistant to its cytotoxic activity. Here we show that TRAF-2-/- embryonic fibroblasts express reduced levels of the anti-apoptotic molecule c-FLIP due to extensive degradation of the protein. Reconstitution of TRAF-2-/- EF with c-FLIP is sufficient for resistance to TNF toxicity. Our results strengthen the role of c-FLIP in protecting cells from the cytotoxic effect of TNF and have implication for the treatment of inflammatory and proliferative disorders.

An appraisal of magnetic resonance imaging of the wrist in rheumatoid arthritis

OBJECTIVES

To evaluate the role of magnetic resonance imaging (MRI) in the diagnosis, staging, and follow-up of the rheumatoid wrist.

METHODS

A Medline search was performed to identify all publications from the years 1985 to 1999 concerning MRI of the wrist in patients with rheumatoid arthritis (RA). Additional papers were retrieved by scanning the references to the Medline-listed articles. Details of the MRI technique, as well as clinical data, were analyzed and compared.

RESULTS

A total of 55 papers were identified. There were considerable variations in imaging sequence, section type, and slice thickness. Erosions and synovitis were the conditions that mostly profited from the adoption of MRI. Although the visualization of erosions was better detailed with MRI than with conventional radiography, erosions were only rarely related to clinical and laboratory parameters. Another advantage was that synovitis imaging, which can be enhanced by contrast agents, was amenable to quantitation. The extent of the synovial surface and the rate of contrast enhancement in a series of consecutive, rapidly acquired images were the most common measures.

CONCLUSIONS

MRI of the rheumatoid wrist is a useful technique to ascertain the criteria for diagnosis and progression of RA, and to monitor the effects of treatment. Implementation of a standardized protocol could further increase its value.

Thyroid-hormone effects on putative biochemical pathways involved in UCP3 activation in rat skeletal muscle mitochondria

In vitro, uncoupling protein 3 (UCP3)-mediated uncoupling requires cofactors [e.g., superoxides, coenzyme Q (CoQ) and fatty acids (FA)] or their derivatives, but it is not yet clear whether or how such activators interact with each other under given physiological or pathophysiological conditions. Since triiodothyronine (T3) stimulates lipid metabolism, UCP3 expression and mitochondrial uncoupling, we examined its effects on some biochemical pathways that may underlie UCP3-mediated uncoupling. T3-treated rats (Hyper) showed increased mitochondrial lipid-oxidation rates, increased expression and activity of enzymes involved in lipid handling and increased mitochondrial superoxide production and CoQ levels. Despite the higher mitochondrial superoxide production in Hyper, euthyroid and hyperthyroid mitochondria showed no differences in proton-conductance when FA were chelated by bovine serum albumin. However, mitochondria from Hyper showed a palmitoyl-carnitine-induced and GDP-inhibited increased proton-conductance in the presence of carboxyatractylate. We suggest that T3 stimulates the UCP3 activity in vivo by affecting the complex network of biochemical pathways underlying the UCP3 activation.

Accurate specimen preparation and examination is mandatory to detect lymph nodes and avoid understaging in colorectal cancer

Lymph node involvement in colorectal cancer, one of the most important prognostic factors, can be sometimes underestimated. In this study the authors report the results of two different techniques of specimen preparation and examination. In 240 patients (Group I), histologic examination was performed using a conventional procedure. In Group II (60 cases) the resected bowel and its mesentery were separately stretched, pinned on to a cork board, and fixed. The mesentery was divided according to node location (intermediate and principal) and evaluated by sight and palpation to identify lymph nodes. The bowel segment was divided from 5 cm proximally to 5 cm distally to the tumor every 10 mm in serial 3 mm slices. Three and 10 mm slices were then carefully examined by sight and palpation. Isolated lymph nodes embedded in groups (10-12 per paraffin block) were stained and investigated for neoplastic involvement. The specimen examination procedure used in Group II resulted in identification of a higher number of lymph nodes (mean = 41.1) and nodal metastases (mean = 10) compared to the standard technique used in Group I (mean = 11.3 and 2.4, respectively--P < .05). The percentage of N+ cases also was increased in Group II (48.3%) when compared to that in Group I (30.4%; P < .05). The new technique is simple, inexpensive, and efficacious for the detection of lymphatic metastases in colorectal cancer.

Skeletal muscle mitochondrial free-fatty-acid content and membrane potential sensitivity in different thyroid states: involvement of uncoupling protein-3 and adenine nucleotide translocase

The effect of triiodothyronine (T3) on mitochondrial efficiency could be related to an increase in the concentrations of some proteins, such as uncoupling proteins (UCPs). Free fatty acids (FFA) seem to be a cofactor essential for the uncoupling activity of UCP3. In this paper, we report that the hypothyroidism-hyperthyroidism transition is accompanied by increases: (i) in the endogenous levels of mitochondrial FFA and (ii) in the sensitivity to FFA shown by the mitochondrial respiration rate and membrane potential, which correlated with the level of UCP3 protein. The level of the mRNA for adenine-nucleotide translocase-1 (ANT) was not affected by the thyroid state, while the ANT contribution to FFA-induced changes in mitochondrial uncoupling was low in the hypothyroid and euthyroid states but became more relevant in the hyperthyroid state at the highest concentration of FFA.

Novel and recurrent mutations in the integrin beta 4 subunit gene causing lethal junctional epidermolysis bullosa with pyloric atresia

In this study we examined two unrelated patients affected with the lethal variant of junctional epidermolysis bullosa with pyloric atresia (PA-JEB) who were found to carry mutations in the integrin beta4 subunit gene (ITGB4). Although in both patients Northern blot analysis showed only a 50% reduction in the level of ITGB4 transcript, a complete lack (patient 1) or a strong reduction (patient 2) of beta4 immunoreactivity was observed in the skin. Using immunoprecipitation analysis, integrin beta4 could not be visualized in patient 1 cells while a markedly reduced amount (approximately 20%) of normal sized beta4 chains was detected in patient 2. These data suggested the presence of ITGB4 mutations that interfere with both mRNA and protein stability. Using molecular analysis, patient 1 was shown to be a compound heterozygous for a single amino acid deletion (deltaN318) and a not yet identified mutation that induces a very rapid decay of the encoded mRNA transcript. Patient 2 was, instead, a compound heterozygous for a novel 4-bp tandem duplication (4298-4299ins4) and a previously described missense mutation (R252C). Our data support the notion that PA-JEB lethal phenotypes associated with a markedly decreased/absent alpha6beta4 expression can be due not only to the presence of null alleles, but also to specific mutations leading to protein instability and/or altered function.