Vangl-dependent Wnt/planar cell polarity signaling mediates collective breast carcinoma motility and distant metastasis

BACKGROUND

In light of the growing appreciation for the role of collective cell motility in metastasis, a deeper understanding of the underlying signaling pathways will be critical to translating these observations to the treatment of advanced cancers. Here, we examine the contribution of Wnt/planar cell polarity (Wnt/PCP), one of the non-canonical Wnt signaling pathways and defined by the involvement of the tetraspanin-like proteins Vangl1 and Vangl2, to breast tumor cell motility, collective cell invasiveness and mammary tumor metastasis.

METHODS

Vangl1 and Vangl2 knockdown and overexpression and Wnt5a stimulation were employed to manipulate Wnt/PCP signaling in a battery of breast cancer cell lines representing all breast cancer subtypes, and in tumor organoids from MMTV-PyMT mice. Cell migration was assessed by scratch and organoid invasion assays, Vangl protein subcellular localization was assessed by confocal fluorescence microscopy, and RhoA activation was assessed in real time by fluorescence imaging with an advanced FRET biosensor. The impact of Wnt/PCP suppression on mammary tumor growth and metastasis was assessed by determining the effect of conditional Vangl2 knockout on the MMTV-NDL mouse mammary tumor model.

RESULTS

We observed that Vangl2 knockdown suppresses the motility of all breast cancer cell lines examined, and overexpression drives the invasiveness of collectively migrating MMTV-PyMT organoids. Vangl2-dependent RhoA activity is localized in real time to a subpopulation of motile leader cells displaying a hyper-protrusive leading edge, Vangl protein is localized to leader cell protrusions within leader cells, and actin cytoskeletal regulator RhoA is preferentially activated in the leader cells of a migrating collective. Mammary gland-specific knockout of Vangl2 results in a striking decrease in lung metastases in MMTV-NDL mice, but does not impact primary tumor growth characteristics.

CONCLUSIONS

We conclude that Vangl-dependent Wnt/PCP signaling promotes breast cancer collective cell migration independent of breast tumor subtype and facilitates distant metastasis in a genetically engineered mouse model of breast cancer. Our observations are consistent with a model whereby Vangl proteins localized at the leading edge of leader cells in a migrating collective act through RhoA to mediate the cytoskeletal rearrangements required for pro-migratory protrusion formation.

Cellular transformation promotes the incorporation of docosahexaenoic acid into the endolysosome-specific lipid bis(monoacylglycerol)phosphate in breast cancer

Bis(monoacylglycero)phosphates (BMPs), a class of lipids highly enriched within endolysosomal organelles, are key components of the lysosomal intraluminal vesicles responsible for activating sphingolipid catabolic enzymes. While BMPs are understudied relative to other phospholipids, recent reports associate BMP dysregulation with a variety of pathological states including neurodegenerative diseases and lysosomal storage disorders. Since the dramatic lysosomal remodeling characteristic of cellular transformation could impact BMP abundance and function, we employed untargeted lipidomics approaches to identify and quantify BMP species in several in vitro and in vivo models of breast cancer and comparative non-transformed cells and tissues. We observed lower BMP levels within transformed cells relative to normal cells, and consistent enrichment of docosahexaenoic acid (22:6) fatty acyl chain-containing BMP species in both human- and mouse-derived mammary tumorigenesis models. Our functional analysis points to a working model whereby 22:6 BMPs serve as reactive oxygen species scavengers in tumor cells, protecting lysosomes from oxidant-induced lysosomal membrane permeabilization. Our findings suggest that breast tumor cells might divert polyunsaturated fatty acids into BMP lipids as part of an adaptive response to protect their lysosomes from elevated reactive oxygen species levels, and raise the possibility that BMP-mediated lysosomal protection is a tumor-specific vulnerability that may be exploited therapeutically.

Preliminary experience with a novel facet-based lateral mass drill guide for the placement of lateral mass screws compared to freehand technique: a cadaveric study

BACKGROUND CONTEXT

Lateral mass screw fixation is the standard for posterior subaxial cervical fixation. Several freehand surgical techniques for placing lateral mass screws have been described which rely on anatomical landmarks and surgeon mastery of the technique to safely place screws. The accuracy of these freehand techniques is inherently variable and can be influenced by a surgeon's level of clinical experience. A novel technique was developed that utilizes the plane of the facet joint to create lateral mass screw pilot holes parallel with the joint line to improve the safety and accuracy of lateral mass screw placement regardless of experience.

PURPOSE

To assess the safety and accuracy of lateral mass screw placement using a novel lateral mass drill guide instrument (LM Guide), compared to standard freehand technique.

STUDY DESIGN

Randomized cadaveric study utilizing multiple surgeon evaluators to compare the safety and accuracy of guided cervical lateral mass placement compared to traditional freehand techniques.

MATERIALS AND METHODS

Lateral mass screws were placed from C3 to C7 in 20 cadaver specimens by 8 spine surgeons of varying levels of clinical experience (4 attendings, 4 fellows). Screws were placed bilaterally using standard anatomic landmarks ("freehand") randomly allocated on one side and using the LM Guide on the other. Cadaveric specimens were imaged with high-resolution CT to assess screw placement. Zone grading for safety was conducted based on screw tip position and clinical severity of screw breach was based on proximity to surrounding neurovascular anatomy. Screws were graded as safe, at-risk, or critical, with at-risk and critical screws considered malpositioned. To assess the accuracy of screw trajectory placed using the LM Guide compared to freehand, sagittal screw angle was measured and compared to an "ideal" screw path parallel to the facet joint line. Freehand and LM Guide groups were compared using Pearson's chi-square correlation.

RESULTS

Screw placement using the LM guide yielded a significantly lower rate of screw malpositioning, with 7 of 91 (7.7%) compared with 18 of 99 (18.2%) screws placed in the At-Risk or Critical Zones, p<.05. Of the 91 screws inserted using the LM Guide, 84 (92.3%) were in the Safe Zone, 7 (7.7%) were At-Risk, and 0 were in Critical zones. There was no incidence of neural or transverse foramen breaches with the LM Guide. In comparison, for the 99 screws inserted freehand, 81 (81.8%) were Safe, 14 (14.1%) were At-Risk, and 4 (4.1%) were in Critical zones. The 4 Critical zone freehand screw breaches included 1 neural foramen breach, 2 transverse foramen breaches, and 1 facet breach. The LM Guide also resulted in higher accuracy of screw trajectory, as indicated by a significant reduction in sagittal screw angle compared with freehand, p<.01. Notably, in the less-experienced surgeon cohort, the LM Guide significantly reduced the sagittal screw angle and resulted in no critical screw breaches compared to 3 critical breaches with freehand technique suggesting there might be a benefit in decreasing the learning curve associated with lateral mass screw placement.

CONCLUSIONS

Lateral mass screw placement with a novel LM Guide that uses the facet joint to control screw trajectory improved the accuracy and reproducibility of screw placement with a significant reduction in screw breach rate and sagittal screw angle compared to freehand techniques regardless of surgeon experience level.

CLINICAL SIGNIFICANCE

The inherent variability of freehand lateral mass screw placement can increase the risk of clinical complications associated with screw malpositioning. The technique presented in this cadaveric study may be a viable alternative to standard freehand technique that can improve the overall safety of lateral mass screw placement.

The Cationic Amphiphilic Drug Hexamethylene Amiloride Eradicates Bulk Breast Cancer Cells and Therapy-Resistant Subpopulations with Similar Efficiencies

The resistance of cancer cell subpopulations, including cancer stem cell (CSC) populations, to apoptosis-inducing chemotherapeutic agents is a key barrier to improved outcomes for cancer patients. The cationic amphiphilic drug hexamethylene amiloride (HMA) has been previously demonstrated to efficiently kill bulk breast cancer cells independent of tumor subtype or species but acts poorly toward non-transformed cells derived from multiple tissues. Here, we demonstrate that HMA is similarly cytotoxic toward breast CSC-related subpopulations that are resistant to conventional chemotherapeutic agents, but poorly cytotoxic toward normal mammary stem cells. HMA inhibits the sphere-forming capacity of FACS-sorted human and mouse mammary CSC-related cells in vitro, specifically kills tumor but not normal mammary organoids ex vivo, and inhibits metastatic outgrowth in vivo, consistent with CSC suppression. Moreover, HMA inhibits viability and sphere formation by lung, colon, pancreatic, brain, liver, prostate, and bladder tumor cell lines, suggesting that its effects may be applicable to multiple malignancies. Our observations expose a key vulnerability intrinsic to cancer stem cells and point to novel strategies for the exploitation of cationic amphiphilic drugs in cancer treatment.

The Emerging and Diverse Roles of Bis(monoacylglycero) Phosphate Lipids in Cellular Physiology and Disease

Although understudied relative to many phospholipids, accumulating evidence suggests that bis(monoacylglycero)phosphate (BMP) is an important class of regulatory lipid that plays key roles in lysosomal integrity and function. BMPs are rare in most mammalian tissues, comprising only a few percent of total cellular lipid content, but are elevated in cell types such as macrophages that rely heavily on lysosomal function. BMPs are markedly enriched in endosomal and lysosomal vesicles compared to other organelles and membranous structures, and their unique sn-1:sn-1′ stereoconfiguration may confer stability within the hydrolytic lysosomal environment. BMP-enriched vesicles serve in endosomal-lysosomal trafficking and function as docking structures for the activation of lysosomal hydrolytic enzymes, notably those involved in the catabolic breakdown of sphingolipids. BMP levels are dysregulated in lysosomal storage disorders, phospholipidosis, metabolic diseases, liver and kidney diseases and neurodegenerative disorders. However, whether BMP alteration is a mediator or simply a marker of pathological states is unclear. Likewise, although BMP acyl chain composition may be altered with disease states, the functional significance of specific BMP species remains to be resolved. Newly developed tools for untargeted lipidomic analysis, together with a deeper understanding of enzymes mediating BMP synthesis and degradation, will help shed further light on the functional significance of BMPs in cellular physiology and pathology.

A Novel Bioengineered miR-127 Prodrug Suppresses the Growth and Metastatic Potential of Triple-Negative Breast Cancer Cells

miR-127 is downregulated in breast cancer, where it has been shown to suppress the proliferation, migration, and invasion of breast cancer cells. In triple-negative breast cancer (TNBC), miR-127 downregulation correlates with decreased disease-free and overall patient survival. Tumor suppressor miRNAs may hold therapeutic promise but progress has been limited by several factors, including the lability and high cost of miRNA mimics. Here, we take a novel approach to produce a miR-127 prodrug (miR-127^PD), which we demonstrate is processed to mature, functional miR-127-3p in TNBC tumor cells. miR-127^PD decreased the viability and motility of TNBC cells, sensitized TNBC cells to chemotherapy, and restricted the TNBC stem cell population. Furthermore, systemic delivery of miR-127^PD suppressed tumor growth of MDA-MB-231 and MDA-MB-468 TNBC cells and spontaneous metastasis of MDA-MB-231 cells. In addition, CERK, NANOS1, FOXO6, SOX11, SOX12, FASN, and SUSD2 were identified as novel, functionally important targets of miR-127. In conclusion, our study demonstrates that miR-127 functions as a tumor and metastasis suppressor in TNBC and that delivery of miR-127 may hold promise as a novel therapy. SIGNIFICANCE: Exogenous administration of miR-127, which is functionally activated in target cells, inhibits growth and spontaneous metastasis of triple-negative breast cancer.

Otubain 1: a non-canonical deubiquitinase with an emerging role in cancer

The ubiquitin system regulates diverse biological processes, many involved in cancer pathogenesis, by altering the ubiquitination state of protein substrates. This is accomplished by ubiquitin ligases and deubiquitinases (DUBs), which respectively add or remove ubiquitin from substrates to alter their stability, activity, localization and interactions. While lack of catalytic activity makes therapeutic targeting of ubiquitin ligases difficult, DUB inhibitors represent an active area of research and the identification of cancer-associated DUBs may lead to the development of novel therapeutics. A growing body of literature demonstrates that the DUB Otubain 1 (OTUB1) regulates many cancer-associated signaling pathways including MAPK, ERa, epithelial-mesenchymal transition (EMT), RHOa, mTORC1, FOXM1 and P53 to promote tumor cell survival, proliferation, invasiveness and therapeutic resistance. In addition, clinical studies have associated elevated OTUB1 expression with high grade, invasiveness and metastasis in several tumor types including lung, breast, ovarian, glioma, colon and gastric. Interestingly, in addition to catalytic DUB activity, OTUB1 displays a catalytic-independent, non-canonical activity where it inhibits the transfer of ubiquitin onto protein substrates by sequestration of E2 ubiquitin-conjugating enzymes. The aim of this review is to describe the canonical and non-canonical activities of OTUB1, summarize roles for OTUB1 in cancer-associated pathways and discuss its potential therapeutic targeting.

Hexamethylene amiloride engages a novel reactive oxygen species- and lysosome-dependent programmed necrotic mechanism to selectively target breast cancer cells

Anticancer chemotherapeutics often rely on induction of apoptosis in rapidly dividing cells. While these treatment strategies are generally effective in debulking the primary tumor, post-therapeutic recurrence and metastasis are pervasive concerns with potentially devastating consequences. We demonstrate that the amiloride derivative 5-(N,N-hexamethylene) amiloride (HMA) harbors cytotoxic properties particularly attractive for a novel class of therapeutic agent. HMA is potently and specifically cytotoxic toward breast cancer cells, with remarkable selectivity for transformed cells relative to non-transformed or primary cells. Nonetheless, HMA is similarly cytotoxic to breast cancer cells irrespective of their molecular profile, proliferative status, or species of origin, suggesting that it engages a cell death mechanism common to all breast tumor subtypes. We observed that HMA induces a novel form of caspase- and autophagy-independent programmed necrosis relying on the orchestration of mitochondrial and lysosomal pro-death mechanisms, where its cytotoxicity was attenuated with ROS-scavengers or lysosomal cathepsin inhibition. Overall, our findings suggest HMA may efficiently target the heterogeneous populations of cancer cells known to reside within a single breast tumor by induction of a ROS- and lysosome-mediated form of programmed necrosis.

Adrenocorticotrophic hormone exerts marked lipid-lowering effects in simvastatin-treated patients

OBJECTIVE

Recently, it was reported that treatment with adrenocorticotrophic hormone (ACTH) has a strong lipid-lowering effect in healthy individuals. The mechanism behind this has not been established. The aim of the present investigation was to study the effect of ACTH on the plasma lipoprotein pattern in patients treated with a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor.

DESIGN

The ACTH treatment was given to 10 patients who were on long-term treatment with simvastatin 40 mg daily. ACTHI-24 was administered at the dose of 1 mg daily for four consecutive days. Blood samples for analyses of lipids, lipoproteins and apolipoproteins were collected before and after treatment. Second baseline was obtained 2 weeks after the end of treatment.

RESULTS

The serum concentrations of cholesterol, triglycerides, low density lipoprotein (LDL) cholesterol, apolipoprotein B and lipoprotein(a) fell significantly by 16, 23, 23, 10 and 38%, respectively. The serum apolipoprotein E concentration increased significantly by 39%; the fraction that was not associated with apolipoprotein B increased by 47% whereas the fraction that was did not change significantly. There were no changes in the serum concentrations of high density lipoprotein (HDL) cholesterol and apolipoprotein AI. At the second baseline, the lipid variables had generally returned to previous levels.

CONCLUSIONS

In patients on long-term simvastatin treatment, ACTH had marked lowering effects on the lipoproteins that contain apolipoprotein B. Moreover, the serum apolipoprotein E concentration increased significantly in response to ACTH treatment.

Wild birds as a possible natural reservoir of Borna disease virus

The natural reservoir of Borna disease virus (BDV) is unknown. In this paper, we show that mallards (Anas platyrhyncos) and jackdaws (Corvus monedula) can be subclinically infected carriers of this virus. From faecal samples collected at a bird pond, we were able to amplify fragments of the BDV p24 and p40 genes. Following cloning and sequencing, a phylogenetic analysis revealed that these birds carry strains of BDV closely related to but distinct from the reference strains BDV V and He/80. To our knowledge, this is the first confirmed finding of BDV in wild birds.

Effects of short-term treatment with corticotropin on the serum apolipoprotein pattern

Treatment with adrenocorticotrophic hormone (ACTH) has a well-documented cholesterol-lowering effect. Increased uptake of low-density lipoprotein (LDL) by HepG2 cells in response to incubation with ACTH has been demonstrated but the precise cholesterol-lowering mechanism has resisted elucidation. Since apolipoproteins are important determinants of lipoprotein metabolism, we sought to extend the knowledge of the effect of ACTH treatment on the serum apolipoprotein (apo) pattern. Twelve healthy individuals and 14 dyslipoproteinemic hemodialysis patients were recruited. The two groups responded similarly to ACTH1-24 at the dose of 1 mg daily for four days. In accordance with previous results, serum concentrations of total cholesterol decreased by 18% and 17%, LDL cholesterol by 25% and 30%, and apo B by 20% and 19%, respectively, while there were no significant changes in the serum concentrations of triglycerides, high-density lipoprotein cholesterol and apo AI. Novel findings were that the serum concentrations of total apo E increased by 48% and 31%, and apo B-associated apo E by 69% and 46%, respectively. Moreover, in the healthy individuals, the serum concentrations of apo CIII did not change in response to ACTH, whereas in the hemodialysis patients, those of apo CIII not associated with apo B increased significantly by 44%. Since apo E binds strongly to the LDL receptor, the present results suggest that the cholesterol-lowering effect of ACTH may be mediated by facilitated hepatic uptake of apo E-enriched apo B-containing lipoproteins. Thus, the findings stimulate further research.

Plasma total homocysteine concentration in nephrotic patients with idiopathic membranous nephropathy

BACKGROUND

The atherothrombotic risk pattern of the nephrotic syndrome resembles that of hyperhomocysteinemia. However, the effect of nephrotic range proteinuria on homocysteine metabolism has never been studied.

METHODS

The study included 11 male nephrotic patients with idiopathic membranous nephropathy who underwent a treatment trial with adrenocorticotrophic hormone and 11 male non-nephrotic, renal function-matched control subjects. The nephrotic patients were studied before and after the treatment, which induced a marked reduction in urinary protein excretion and a moderate improvement in renal function in all cases.

RESULTS

Plasma total homocysteine (tHcy) concentration did not change significantly during treatment, whereas the nephrotic patients had significantly lower tHcy than the non-nephrotic patients (14.2 +/- 3.4 micromol/l vs 19.0 +/- 5.4 micromol/l). tHcy correlated significantly with serum concentrations of creatinine (r = 0.53, P < 0.05) and albumin (r = 0.43, P < 0.05), glomerular filtration rates (GFRs) (iohexol clearances) (r = -0.42, P < 0.05) and urinary albumin excretion (r = -0.47, P < 0.05).

CONCLUSION

The expected tHcy-lowering effect of improved renal function may have masked a tHcy-elevating effect due to reduced proteinuria leading to no net change in tHcy during treatment. The notion of an increase in tHcy associated with remission of the nephrotic syndrome is in accordance with the significantly lower tHcy in the nephrotic renal patients compared with the non-nephrotic renal function-matched patients, and the relationships between tHcy and serum albumin concentrations as well as urinary albumin excretion. Thus, the results of this small study suggest that nephrotic range proteinuria directs homocysteine metabolism towards a decrease in tHcy. However, the findings need to be confirmed in larger patient populations and in different varieties of the nephrotic syndrome.

Borna disease in a free-ranging lynx (Lynx lynx)

A free-ranging lynx (Lynx lynx) was shot because of its abnormal behavior. Histopathological examination revealed a nonsuppurative meningoencephalitis. In situ hybridization, immunohistochemistry, and reverse transcriptase PCR analysis showed the presence of Borna disease virus infection in the brain. To our knowledge, this is the first confirmed case of Borna disease in a large felid.

Ototoxic impact of cisplatin in pediatric oncology patients

OBJECTIVE

To describe hearing changes in a group of 28 children (age range, 8-180 mo) undergoing protocol-based cisplatin therapy.

METHODS

Conventional, play audiometry, visual reinforcement audiometry (VRA), immittance audiometry, transient click evoked otoacoustic emissions (OAEs), and auditory brainstem response (ABR) evoked potentials were used to assess peripheral sensitivity and for threshold determination.

RESULTS

Bilateral symmetrical high-frequency sensorineural hearing loss was noted in 9 of the 28 children (26%). Hearing loss was evident as early as 1 month after chemotherapy and as late as 50 months and was not dependent on individual or cumulative dosage of cisplatin.

CONCLUSIONS

1) Presence of sensorineural hearing loss was independent of individual and/or cumulative dosage of cisplatin; 2) audiologic assessment should be incorporated into a child's periodic medical evaluations after chemotherapy treatment, as onset of sensorineural hearing loss cannot be predicted; 3) personal hearing aids may be indicated for those children with hearing loss affecting the low- to mid-frequencies; a personal assistive listening device (frequency modulated system) may be more appropriate for losses above 3000 Hz; and 4) evaluation and intervention by a speech-language pathologist may be indicated to address possible articulation or language development problems consequent to hearing loss.

Beneficial effects of ACTH on the serum lipoprotein profile and glomerular function in patients with membranous nephropathy

BACKGROUND

Previous studies have shown that short-term treatment with adrenocorticotrophic hormone (ACTH) has a strong and rapid lipid-lowering effect. In this long-term study of nephrotic patients with idiopathic membranous nephropathy, the influence of ACTH on the serum lipoprotein profile and glomerular function as well as the dose-effect relationship was investigated.

METHODS

Fourteen patients received ACTH intramuscularly at increasing doses during 56 days. Serum concentrations of lipids, lipoproteins, and apolipoproteins as well as variables of glomerular function were analyzed, and the side-effects were recorded. ACTH treatment, in the estimated optimal dosage, was then continued in five patients with severe steroid-resistant nephrotic syndrome. In these five patients, the total treatment period was 12 months, and the follow-up time after discontinuing treatment was 18 months.

RESULTS

Taking both the statistically significant therapeutic effects and the modest side-effects into consideration, the optimal dosage of ACTH was estimated to be 1 mg twice per week. At that dose, reductions by 30 to 60% in the serum concentrations of cholesterol, triglycerides, apolipoprotein B, and lipoprotein(a) were observed, whereas the serum concentrations of high-density lipoprotein cholesterol and apolipoprotein AI rose by 30 to 40%. In addition, the urinary albumin excretion decreased by 90%, and the glomerular filtration rate increased by 25%. Deterioration was observed in all cases when ACTH was discontinued after a treatment duration of 56 days. However, the five patients in whom ACTH therapy was resumed were still in remission 18 months after discontinuance of treatment.

CONCLUSIONS

In nephrotic patients with idiopathic membranous nephropathy, treatment with ACTH 1 mg twice per week was associated with significant long-term improvements in serum lipoprotein pattern and glomerular function.

Borna disease virus infection in racing horses with behavioral and movement disorders

Borna disease virus (BDV) is a neurotropic agent with capacity to infect and cause neurological disease in a broad range of warmblooded hosts including horses, sheep, cattle, cats, and possibly also humans. The epidemiology of BDV is largely unknown. However, it is likely that subclinically infected animals may represent potential virus reservoirs. In two groups of Swedish racing horses, one clinically healthy and one consisting of horses with diffuse neurological signs, the BDV seroprevalence was 24.5% and 57.7%, respectively. BDV RNA was detected in peripheral blood mononuclear cells in 8 out of 28 (28.6%) investigated horses, the majority of the BDV RNA-positive horses belonging to the group with neurological signs. There was a close relationship between the Swedish equine BDV isolates and previously reported equine BDVs in Europe. Our results point to an association of BDV infection with atypical disease patterns in horses such as diffuse mental and gait disturbances. These findings may be of importance for the understanding of the epidemiology of BDV infections in animals and man.

Peripheral and intracerebral T cell immune response in cats naturally infected with Borna disease virus

Borna disease virus (BDV) is a neurotropic agent with capacity to cause encephalomyelitis in a wide range of animal species, including horses and cats. Recent studies also point to a link between BDV and human neuropsychiatric disorders. The pathogenesis of Borna disease (BD) has been proposed to be immune-mediated, mainly through the effects of cytotoxic T cells. We used flow cytometric analysis in order to characterize the peripheral and intracerebral T cell immune response in cats naturally infected with BDV. Our results show the presence of two different CD8+ cell populations (CD8+low and CD8+high) in the blood, spleen and brain of these cats. In the brain, CD8+low cells predominated over CD8+high cells. Since CD8+low cells have been suggested to represent a non-MHC-restricted T cell population, the recruitment of such cells to the brains of BDV-infected cats could possibly be of importance for the clearance of virus from neurones.

Corticotropin-induced reduction of plasma lipoprotein(a) concentrations in healthy individuals and hemodialysis patients: relation to apolipoprotein(a) size polymorphism

Lipoprotein(a) [Lp(a)], a strong independent cardiovascular risk factor, consists of the unique apolipoprotein(a) [apo(a)] covalently linked to a low-density lipoprotein particle. Apo(a) contains a widely differing number of the plasminogen-like kringle IV, a size polymorphism that is codominantly inherited. In addition to powerful genetic control, renal failure is known to influence the plasma Lp(a) concentration. There is still a lot to be learned about the mode and site of catabolism of Lp(a), and there is no readily applicable Lp(a)-lowering treatment available. Therefore, it was of interest to study further the Lp(a)-lowering effect of corticotropin (ACTH) that has been demonstrated in small studies. The main purpose of the present study was to investigate the influence of ACTH on different apo(a) isoforms. Short-term treatment with ACTH decreased the plasma Lp(a) concentration in all 26 study participants. The two study groups (12 healthy individuals and 14 hemodialysis patients) responded similarly, with a median decrease in plasma Lp(a) of 39% and 49%, respectively. In subjects with two clearly separable apo(a) bands, apo(a) phenotyping and densitometric scanning of the bands before and after treatment with ACTH revealed a change in the proportion of apo(a) isoforms, ie, a shift toward the isoform with lower molecular weight. This was observed in seven of nine investigated subjects (four of five healthy individuals and three of four hemodialysis patients).

Influence of haemodialysis on plasma total homocysteine concentration

BACKGROUND

The high prevalence of hyperhomocysteinaemia in uraemic patients is of interest because of the cardiovascular risk associated with increased plasma total homocysteine (tHcy) concentration. Treatment with folic acid lowers tHcy in haemodialysis patients, however, in most patients not to normohomocysteinaemic levels. With possible tHcy-lowering modifications in mind, we studied the influence of standard haemodialysis on tHcy.

METHODS

In 56 folate-loaded haemodialysis patients, tHcy and parameters of dialysis adequacy were measured. In six patients, interdialytic curves of tHcy and serum creatinine concentrations were obtained and in five patients, the amount of homocysteine (Hcy) in dialysate was determined.

RESULTS

tHcy (21.8+/-14.4 micromol/l) correlated significantly with Kt/V (r=0.32, P<0.05), total Kt/V (r=0.29, P<0.05), nPCR (r=0.30, P<0.05) and serum concentrations of albumin (r=0.28, P<0.05) and cobalamines (r=-0.27, P<0.05). In a multiple linear regression analysis, only serum albumin concentrations significantly predicted tHcy (r=0.34, P < 0.05). During dialysis, tHcy decreased by 28% and remained constant for at least 8 h after treatment. The amount of Hcy recovered in dialysate was 63 micromol (12-158 micromol). There was no difference in tHcy between those who had residual renal function and those who had not.

CONCLUSIONS

The direct relationship between tHcy and Kt/V seemed to be mediated by the serum albumin concentration. The shape of the interdialytic tHcy curve suggested facilitated Hcy removal for at least 8 h after dialysis possibly due to reduced levels of inhibitory activities against relevant enzyme(s). The dialysed amount of Hcy did not seem to contribute significantly to Hcy removal. Thus, modifications of standard dialytic regimens are not likely to be effective from a tHcy-lowering point of view whereas convective procedures such as haemofiltration or haemodiafiltration might be more effective.

Pervasive developmental delay in children presenting as possible hearing loss

OBJECTIVE/HYPOTHESIS

Children who fail to develop adequate language skills and/or appropriate social skills by age 2 years often are referred to the department of otolaryngology for otolaryngologic examination and evaluation of possible hearing deficits. Discovering a gross disparity between hearing function and language ability often uncovers an underlying developmental disorder satisfying criteria for diagnosis on the spectrum of autism and pervasive developmental delay (PDD). The otolaryngologist has a unique opportunity to identify these autistic children and initiate their evaluation and management.

STUDY DESIGN

Retrospective review.

METHODS

Review of charts of children referred over the past 4 years to the Department of Otolaryngology for possible hearing loss identified 15 children who were later diagnosed with PDD.

RESULTS

Fifteen children initially referred for hearing evaluation were subsequently identified with a diagnosis of PDD. Males outnumbered females 4 to 1, with the average age of referral being 2 years. One third of the patients displayed middle ear disease that improved with PE tube placement. One third of the patients showed brainstem conduction dysfunction on auditory brainstem evoked response testing.

CONCLUSIONS

Children with developmental delays, especially higher functioning ones, may present with a myriad of language and communication deficits that are often mistakenly attributed to hearing loss. Otolaryngologists and audiologists can assist in their early identification and appropriate referral for therapy.

Two domains of the Borna disease virus p40 protein are required for interaction with the p23 protein

Borna disease virus (BDV) has five major open reading frames, which encode the proteins p40, p23, gp18, p57 and p190. By analogy with other negative-strand RNA viruses, p40 is a putative nucleoprotein and p23 is a putative phosphoprotein. These proteins are known to form complexes with each other and with the polymerase protein in other viruses. In this paper, it is shown that BDV p40 and p23 can form complexes with each other in infected cells. Furthermore, the amino acids of p40 that are necessary for formation of this complex have been mapped.

A variant form of feline Borna disease

Borna disease virus (BDV) is a neurotropic agent with capacity to infect and cause encephalomyelitis in a wide range of animals, including horses, sheep, cattle and cats. Recent interest in BDV as a potential human pathogen has been stimulated by reports of BDV-specific antibodies and nucleic acid in patients with neuropsychiatric diseases. The pathogenesis of Borna disease (BD) in naturally infected animals is believed to be immune-mediated, mainly through the action of cytotoxic T cells. In this paper, a case of feline BD with atypical clinical and histopathological features is reported. Clinically, the cat showed muscle fasciculation and proprioceptive defects. Despite absence of encephalitis, numerous neurons were infected with BDV as shown by in-situ hybridization. This indicates that BDV infection may lead to various disease patterns, depending on differences in viral pathogenicity, or on as yet unidentified host-specific factors.

Case control study of feline Borna disease in Sweden

A questionnaire-based, retrospective case-control study of 174 Swedish cats was used to identify possible risk factors for feline Borna disease. The questionnaire consisted of 32 questions on a wide range of subjects, including lifestyle and possible modes of virus transmission. Two control groups were used: a healthy-control and a hospital-control. Variables with significant odds ratios in either the Borna disease:healthy-control or Borna disease:hospital-control comparison were included in multiple logistic regression analyses. Overall, the models suggested that feline Borna disease has a predominantly rural/woodland distribution, that affected cats were more likely to be males than females and intact than neutered, and that they were more likely than not to have hunted mice. The results indicate that, in contrast to other feline viral infections, Borna disease virus is not readily transmitted between cats. The natural reservoir of the virus is unknown. The fact that exposure to mice by hunting was a risk factor for the disease suggests that rodents may be subclinically infected and act as virus carriers.

Adrenocorticotrophic hormone lowers serum Lp(a) and LDL cholesterol concentrations in hemodialysis patients

Previously, we have shown that short-term administration of adrenocorticotrophic hormone (ACTH) results in reduced concentrations of apolipoprotein B-containing lipoproteins, including lipoprotein(a), and reduced activities of hepatic lipase. These effects were observed in steroid-treated patients suffering from iatrogenic ACTH deficiency and in healthy individuals. The direct nature of the influence of ACTH on hepatic lipoprotein metabolism was confirmed by in vitro experiments. The aim of the present investigation was to study the effects of ACTH treatment on uremic patients, who exhibit disturbed lipoprotein pattern due to the slow removal of triglyceride-rich lipoproteins and who probably are ACTH resistant. Eight patients on chronic hemodialysis were studied. After one intramuscular injection of Synacthen Depot (a synthetic ACTH1-24 preparation from Ciba Geigy AG, Basel, Switzerland) 1 mg, the only change noted was a significant reduction of 26% in median lipoprotein(a) concentration. After five injections, a further decrease (65%) was found in the lipoprotein(a) concentration. Also, reductions in median concentrations of total cholesterol, low density lipoprotein cholesterol and apolipoprotein B were observed. The magnitude of these changes was 15 to 30%. In contrast to previously studied groups, no changes were observed regarding triglyceride metabolism. Significantly increased median concentration of apolipoprotein CIII was found. However, the excess apolipoprotein CIII was confined to the fraction that was not associated with apolipoprotein B. Thus, administration of ACTH to uremic patients improved their atherogenic lipoprotein profile, a fact that may have future therapeutic implications. In comparison to previously studied groups, the uremic patients responded rather slowly and not at all regarding triglyceride metabolism.

ACTH lowers serum lipids in steroid-treated hyperlipemic patients with kidney disease

The mechanisms behind secondary hyperlipidemia in patients with various chronic inflammatory diseases are not known in detail. We have recently demonstrated that ACTH exerts strong hypolipidemic effects in healthy volunteers. To test the clinical relevance of this finding, we administrated ACTH during three weeks to nine hyperlipidemic steroid-treated patients with kidney disease. Before administration of ACTH 1-24, plasma ACTH concentrations were low. Treatment with ACTH led to 20 to 50% reductions in serum concentrations of triglycerides, cholesterol, LDL cholesterol and Apo B as well as of Lp(a). HDL cholesterol and Apo A1 concentrations increased by 10 to 25%. HL activity in postheparin plasma decreased by about 40% and LPL activity, which was initially low, increased by about 140%. The effects of ACTH were similar in kidney transplant recipients and in patients with inflammatory kidney disease. Our results indicate that hyperlipidemia in steroid treated patients with kidney disease may at least partly be due to iatrogenic ACTH deficiency.

Hepatic lipase secretion in human hepatoblastoma cell line Hep G2 is not related to cellular cholesterol homeostasis

The human hepatoblastoma cell line Hep G2 releases the enzyme hepatic lipase during incubation with heparin. In this study, hepatic lipase activity was released by low concentrations of heparin, and the release was linear with time for up to about 10 hours. Preincubations of cells with LDL or compactin induced marked but differential changes in hepatic lipase secretion, cellular cholesterol content and low density lipoprotein receptor activity, suggesting that the secretion of hepatic lipase is regulated independently of cholesterol homeostasis.

Direct effects of corticotropin on plasma lipoprotein metabolism in man--studies in vivo and in vitro

To explore the roles of corticotropin and corticosteroids in the regulation of plasma lipoprotein concentrations, we investigated the effects of 4 days' administration of corticotropin 1-24 (Synacthen Depot, CIBA-Geigy, Basel, Switzerland) in healthy volunteers and compared them with those occurring during treatment with a synthetic glucocorticoid (dexamethasone). Corticotropin administration resulted in rapid decreases of apolipoprotein (apo) B, low-density lipoprotein (LDL) cholesterol, and plasma triglyceride concentrations of 20% to 30%, whereas dexamethasone treatment did not affect any of the apo B-containing lipoproteins. Lipoprotein (a) [Lp(a)] level was decreased by about 30%; in this case, a similar reduction was noted after dexamethasone treatment. High-density lipoprotein (HDL) concentrations increased with both treatments; however, apo A-I concentrations increased only with glucocorticoid treatment, whereas HDL cholesterol level was elevated after both regimens. The activity of hepatic lipase (HL) was significantly decreased after corticotropin, but not after glucocorticoid treatment. LDL receptor activity, studied in cultured Hep G2 cells, was upregulated by about 30% after incubation with corticotropin. We conclude that corticotropin exerts direct effects on lipoprotein metabolism in man, primarily on apo B-containing lipoproteins, which decrease probably due to a corticotropin-mediated upregulation of LDL receptor activity. The metabolism of Lp (a) seems to be primarily influenced by corticosteroids, which rapidly decrease Lp (a) concentrations. An inhibitory effect of corticotropin on HL activity seems to contribute, besides glucocorticoid effects on apo A-I metabolism, to the increase in HDL level.

Salt resistant lipase activity in human adrenal gland is increased in Cushing's disease

Salt resistant lipase (also designated hepatic lipase) is present in normal human adrenal cortex at activity levels of about 1 mU g-1 tissue wet weight. In hyperplastic adrenocortical tissue from four patients with Cushing's disease the salt resistant lipase activity was found to be about 5-fold higher than this value. The activity of salt resistant lipase in postheparin plasma was elevated in two of the patients, indicating that the high enzyme activity in adrenal cortex may originate from the liver. Lipoprotein lipase activity in postheparin plasma was clearly depressed in all patients with Cushing's disease and was associated with moderate hypertriglyceridaemia and slightly lowered HDL cholesterol levels. Thus high ACTH and/or corticosteroid levels appear to affect lipoprotein metabolism by a number of mechanisms.

Hepatic lipase activity after liver denervation in hypothyroid rats

Hepatic hilar denervation, hepatic vagotomy or sham operation were performed in hypothyroid rats. Activities of hepatic lipase were measured nine days after surgery. Sham operation in itself was associated with a decrease of hepatic lipase activity by about 40% compared with non-operated animals. Both hilar denervation and hepatic vagotomy were associated with increased hepatic lipase activity (40% and 35%, compared with sham-operated animals). Liver contents of norepinephrine were reduced by about 90% after hilar denervation, whereas hepatic vagotomy did not affect norepinephrine levels. No major changes in lipids and lipoproteins were noted.