SARS-CoV2 Nsp3 protein triggers cell death and exacerbates amyloid β42-mediated neurodegeneration

JOURNAL/nrgr/04.03/01300535-202406000-00044/inline-graphic1/v/2023-10-30T152229Z/r/image-tiff

Infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) virus, responsible for the coronavirus disease 2019 (COVID-19) pandemic, induces symptoms including increased inflammatory response, severe acute respiratory syndrome (SARS), cognitive dysfunction like brain fog, and cardiovascular defects. Long-term effects of SARS-CoV2 COVID-19 syndrome referred to as post-COVID-19 syndrome on age-related progressive neurodegenerative disorders such as Alzheimer’s disease remain understudied. Using the targeted misexpression of individual SARS-CoV2 proteins in the retinal neurons of the Drosophila melanogaster eye, we found that misexpression of nonstructural protein 3 (Nsp3), a papain-like protease, ablates the eye and generates dark necrotic spots. Targeted misexpression of Nsp3 in the eye triggers reactive oxygen species production and leads to apoptosis as shown by cell death reporters, terminal deoxynucleotidyl transferase (TdT) dUTP Nick-end labeling (TUNEL) assay, and dihydroethidium staining. Furthermore, Nsp3 misexpression activates both apoptosis and autophagy mechanism(s) to regulate tissue homeostasis. Transient expression of SARS-CoV2 Nsp3 in murine neuroblastoma, Neuro-2a cells, significantly reduced the metabolic activity of these cells and triggers cell death. Misexpression of SARS-CoV2 Nsp3 in an Alzheimer’s disease transgenic fly eye model (glass multiple repeats [GMR]>amyloid β42) further enhances the neurodegenerative rough eye phenotype due to increased cell death. These findings suggest that SARS-CoV2 utilizes Nsp3 protein to potentiate cell death response in a neurodegenerative disease background that has high pre-existing levels of neuroinflammation and cell death.

miR-277 targets the proapoptotic gene-hid to ameliorate Aβ42-mediated neurodegeneration in Alzheimer's model

Alzheimer's disease (AD), an age-related progressive neurodegenerative disorder, exhibits reduced cognitive function with no cure to date. One of the reasons for AD is the accumulation of Amyloid-beta 42 (Aβ42) plaque(s) that trigger aberrant gene expression and signaling, which results in neuronal cell death by an unknown mechanism(s). Misexpression of human Aβ42 in the developing retina of Drosophila exhibits AD-like neuropathology. Small non-coding RNAs, microRNAs (miRNAs), post-transcriptionally regulate the expression of their target genes and thereby regulate different signaling pathways. In a forward genetic screen, we identified miR-277 (human ortholog is hsa-miR-3660) as a genetic modifier of Aβ42-mediated neurodegeneration. Loss-of-function of miR-277 enhances the Aβ42-mediated neurodegeneration. Whereas gain-of-function of miR-277 in the GMR > Aβ42 background downregulates cell death to maintain the number of neurons and thereby restores the retinal axonal targeting defects indicating the functional rescue. In addition, gain-of-function of miR-277 rescues the eclosion- and climbing assays defects observed in GMR > Aβ42 background. Thus, gain-of-function of miR-277 rescues both structurally as well as functionally the Aβ42-mediated neurodegeneration. Furthermore, we identified head involution defective (hid), an evolutionarily conserved proapoptotic gene, as one of the targets of miR-277 and validated these results using luciferase- and qPCR -assays. In the GMR > Aβ42 background, the gain-of-function of miR-277 results in the reduction of hid transcript levels to one-third of its levels as compared to GMR > Aβ42 background alone. Here, we provide a novel molecular mechanism where miR-277 targets and downregulates proapoptotic gene, hid, transcript levels to rescue Aβ42-mediated neurodegeneration by blocking cell death. These studies shed light on molecular mechanism(s) that mediate cell death response following Aβ42 accumulation seen in neurodegenerative disorders in humans and provide new therapeutic targets for neurodegeneration.

N-Acetyltransferase 9 ameliorates Aβ42-mediated neurodegeneration in the Drosophila eye

Alzheimer's disease (AD), a progressive neurodegenerative disorder, manifests as accumulation of amyloid-beta-42 (Aβ42) plaques and intracellular accumulation of neurofibrillary tangles (NFTs) that results in microtubule destabilization. Targeted expression of human Aβ42 (GMR > Aβ42) in developing Drosophila eye retinal neurons results in Aβ42 plaque(s) and mimics AD-like extensive neurodegeneration. However, there remains a gap in our understanding of the underlying mechanism(s) for Aβ42-mediated neurodegeneration. To address this gap in information, we conducted a forward genetic screen, and identified N-acetyltransferase 9 (Mnat9) as a genetic modifier of GMR > Aβ42 neurodegenerative phenotype. Mnat9 is known to stabilize microtubules by inhibiting c-Jun-N- terminal kinase (JNK) signaling. We found that gain-of-function of Mnat9 rescues GMR > Aβ42 mediated neurodegenerative phenotype whereas loss-of-function of Mnat9 exhibits the converse phenotype of enhanced neurodegeneration. Here, we propose a new neuroprotective function of Mnat9 in downregulating the JNK signaling pathway to ameliorate Aβ42-mediated neurodegeneration, which is independent of its acetylation activity. Transgenic flies expressing human NAT9 (hNAT9), also suppresses Aβ42-mediated neurodegeneration thereby suggesting functional conservation in the interaction of fly Mnat9 or hNAT9 with JNK-mediated neurodegeneration. These studies add to the repertoire of molecular mechanisms that mediate cell death response following accumulation of Aβ42 and may provide new avenues for targeting neurodegeneration.

Common Sleep Disorders in Children

Childhood sleep disorders can disrupt family dynamics and cause cognitive and behavior problems. Early recognition and management can prevent these complications. Behavior subtypes of childhood insomnias affect 10% to 30% of children and result from inconsistent parental limit-setting and improper sleep-onset association. Behavior insomnias are treated using extinction techniques and parent education. Hypnotic medications are not recommended. Obstructive sleep apnea affects 1% to 5% of children. Polysomnography is required to diagnose obstructive sleep apnea; history and physical examination alone are not adequate. Adenotonsillectomy is the first-line treatment for obstructive sleep apnea. Nasal continuous positive airway pressure is the second-line treatment for children who do not respond to surgery or if adenotonsillectomy is contraindicated. Restless legs syndrome can be difficult to recognize and has an association with attention-deficit/hyperactivity disorder. Management of restless legs syndrome includes treatment of iron deficiency, if identified, and removal of triggering factors. Parasomnias affect up to 50% of children and usually resolve spontaneously by adolescence. Management of parasomnias involves parental education, reassurance, safety precautions, and treating comorbid conditions. Delayed sleep phase syndrome is found during adolescence, manifesting as a night owl preference. Treatment of delayed sleep phase syndrome includes sleep hygiene, nighttime melatonin, and morning bright light exposure. Sleep deprivation is of increasing concern, affecting 68% of people in high school.

A Two-Clone approach to study signaling interactions among neuronal cells in a pre-clinical Alzheimer's Disease model

BACKGROUND

Alzheimer's disease (AD) is a debilitating neurodegenerative disorder with no cure and few treatments. AD causes profound cognitive deficits and memory impairments. Accumulation of the peptide amyloid beta plaque is one of the characteristics of the disease. To understand the progression of Alzheimer's disease, studies often rely on ectopic expression of amyloid-beta 42 (Aβ42) throughout an entire tissue. Uniform ectopic expression of Aβ42 may obscure cell-cell interactions that contribute to the progression of the disease.

METHOD

We developed a two-clone system to study the signaling cross talk between GFP-labeled clones of Aβ42-expressing neurons and wild-type neurons simultaneously generated from the same progenitor cell by a single recombination event.

RESULT

Surprisingly, wild-type clones are reduced in size as compared with Aβ42-producing clones. We found that wildtype cells are eliminated by the induction of cell death. Furthermore, aberrant activation of c-Jun-N-terminal kinase (JNK) signaling in Aβ42-expressing neurons sensitizes neighboring wild-type cells to undergo progressive neurodegeneration. Blocking JNK signaling in Aβ42-producing clones restores the size of wildtype clones.

CONCLUSION

Here we present evidence that JNK signaling between Aβ42- expressing cells and adjacent wild-type cells mediate neurodegeneration.

miR-277 targets hid to ameliorate Aβ42-mediated neurodegeneration in Drosophila eye model of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD), an age-related progressive neurodegenerative disorder, exhibits reduced cognitive functions with no cure to date. One of the reasons for AD is the extracellular accumulation of Amyloid-beta 42 (Aβ42) plaques. Misexpression of human Aβ42 in the developing retina of Drosophila exhibits AD-like neuropathology. Accumulation of Aβ42 plaque(s) triggers aberrant signaling resulting in neuronal cell death by unknown mechanism(s).

METHOD

Alzheimer's disease (AD), an age-related progressive neurodegenerative disorder, exhibits reduced cognitive functions with no cure to date. One of the reasons for AD is the extracellular accumulation of Amyloid-beta 42 (Aβ42) plaques. Misexpression of human Aβ42 in the developing retina of Drosophila exhibits AD-like neuropathology. Accumulation of Aβ42 plaque(s) triggers aberrant signaling resulting in neuronal cell death by unknown mechanism(s).

RESULT

Gain-of-function of mir-277 rescues Aβ42 mediated neurodegeneration whereas loss-of-function of mir-277 enhances Aβ42 mediated neurodegeneration. Moreover, misexpression of higher levels of mir-277 in the GMR>Aβ42 background restores the retinal axonal targeting indicating functional rescue. Furthermore, we have identified head involution defective (hid) as one of the targets of mir-277. The hid transcript levels are decreased by one third when mir-277 is misexpressed in the GMR>Aβ42 background in comparison to the GMR>Aβ42 fly model.

CONCLUSION

Hereby we provide a mechanism of how mir-277 modulates Aβ42 mediated neurodegeneration by regulating hid transcript levels and demonstrate its neuroprotective role in Aβ42-mediated neuropathology.

Newt regeneration genes regulate Wingless signaling to restore patterning in Drosophila eye

Newts utilize their unique genes to restore missing parts by strategic regulation of conserved signaling pathways. Lack of genetic tools poses challenges to determine the function of such genes. Therefore, we used the Drosophila eye model to demonstrate the potential of 5 unique newt (Notophthalmus viridescens) gene(s), viropana1-viropana5 (vna1-vna5), which were ectopically expressed in L 2 mutant and GMR-hid, GMR-GAL4 eye. L 2 exhibits the loss of ventral half of early eye and head involution defective (hid) triggers cell-death during later eye development. Surprisingly, newt genes significantly restore missing photoreceptor cells both in L 2 and GMR>hid background by upregulating cell-proliferation and blocking cell-death, regulating evolutionarily conserved Wingless (Wg)/Wnt signaling pathway and exhibit non-cell-autonomous rescues. Further, Wg/Wnt signaling acts downstream of newt genes. Our data highlights that unique newt proteins can regulate conserved pathways to trigger a robust restoration of missing photoreceptor cells in Drosophila eye model with weak restoration capability.

Impact of RASSF1A gene methylation on clinico-pathological features of tumor and non-tumor tissue of breast cancer

BACKGROUND

Breast cancer is the most common malignancy in women caused by genetic and epigenetic changes. Promoter DNA methylation in tumor suppressor gene plays a major role in breast cancer. The study determined the association of promoter DNA methylation of RASSF1A gene with clinicopathological features in tumor and non-tumor tissue.

MATERIALS AND METHODS

A cross sectional study was conducted in the Department of Pathology, Government Institute of Medical Sciences, Greater Noida and Molecular Pathology Laboratory, Department of Pathology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences. Two sections, one from tumor and the other from non-tumor tissue, were obtained and processed for DNA extraction and bisulphite conversion. Methylation specific PCR was done and results of RASSF1A promoter methylation were statistically correlated with clinicopathological features.

RESULTS

Of the 27 breast cancer tissue, 22 showed invasive ductal carcinoma, one showed invasive lobular carcinoma, another showed ductal carcinoma in situ and three cases showed malignant phyllodes tumor of breast. DNA promoter methylation was found in all the cases. 93% of tumor tissue samples and 67% of the non-tumor tissue samples were found to be aberrantly methylated. Tumor size and histological grade were found to be significantly (p-val <0.05) associated with the RASSF1A gene promoter methylation.

CONCLUSION

A significant association of higher tumor size and tumor histological grade with promoter methylation of RASSF1A gene exists suggestive of its being an important determinant of prognostic staging. This critical event in tumorigenesis may be of clinical utility in assessing breast cancer progression.

MICRO ABSTRACT

The study focuses on the RASSF1A gene promoter methylation and its impact on the clinicopathological features in Indian breast cancer patients highlighting the differences from other genetically different population. We found that RASFF1A gene methylation has significant impact on tumor size and tumor grade. The work carries high significance because it addresses the DNA methylation of tumor suppressor gene in relevance of breast cancer. It may also be the first such report on Indian patients with breast cancer.

Hippo signaling: bridging the gap between cancer and neurodegenerative disorders

During development, regulation of organ size requires a balance between cell proliferation, growth and cell death. Dysregulation of these fundamental processes can cause a variety of diseases. Excessive cell proliferation results in cancer whereas excessive cell death results in neurodegenerative disorders. Many signaling pathways known-to-date have a role in growth regulation. Among them, evolutionarily conserved Hippo signaling pathway is unique as it controls both cell proliferation and cell death by a variety of mechanisms during organ sculpture and development. Neurodegeneration, a complex process of progressive death of neuronal population, results in fatal disorders with no available cure to date. During normal development, cell death is required for sculpting of an organ. However, aberrant cell death in neuronal cell population can result in neurodegenerative disorders. Hippo pathway has gathered major attention for its role in growth regulation and cancer, however, other functions like its role in neurodegeneration are also emerging rapidly. This review highlights the role of Hippo signaling in cell death and neurodegenerative diseases and provide the information on the chemical inhibitors employed to block Hippo pathway. Understanding Hippo mediated cell death mechanisms will aid in development of reliable and effective therapeutic strategies in future.

A Two-Clone Approach to Study Signaling Interactions among Neuronal Cells in a Pre-clinical Alzheimer's Disease Model

To understand the progression of Alzheimer's disease, studies often rely on ectopic expression of amyloid-beta 42 (Aβ42) throughout an entire tissue. Uniform ectopic expression of Aβ42 may obscure cell-cell interactions that contribute to the progression of the disease. We developed a two-clone system to study the signaling cross talk between GFP-labeled clones of Aβ42-expressing neurons and wild-type neurons simultaneously generated from the same progenitor cell by a single recombination event. Surprisingly, wild-type clones are reduced in size as compared with Aβ42-producing clones. We found that wild-type cells are eliminated by the induction of cell death. Furthermore, aberrant activation of c-Jun-N-terminal kinase (JNK) signaling in Aβ42-expressing neurons sensitizes neighboring wild-type cells to undergo progressive neurodegeneration. Blocking JNK signaling in Aβ42-producing clones restores the size of wild-type clones.

An E3 ubiquitin ligase, cullin-4 regulates retinal differentiation in Drosophila eye

During organogenesis, cell proliferation is followed by the differentiation of specific cell types to form an organ. Any aberration in differentiation can result in developmental defects, which can result in a partial to a near-complete loss of an organ. We employ the Drosophila eye model to understand the genetic and molecular mechanisms involved in the process of differentiation. In a forward genetic screen, we identified, cullin-4 (cul-4), which encodes an E3 ubiquitin ligase, to play an important role in retinal differentiation. During development, cul-4 is known to be involved in protein degradation, regulation of genomic stability, and regulation of cell cycle. Previously, we have reported that cul-4 regulates cell death during eye development by downregulating Wingless (Wg)/Wnt signaling pathway. We found that loss-of-function of cul-4 results in a reduced eye phenotype, which can be due to onset of cell death. However, we found that loss-of-function of cul-4 also affects retinal development by downregulating retinal determination (RD) gene expression. Early markers of retinal differentiation are dysregulated in cul-4 loss of function conditions, indicating that cul-4 is necessary for differentiation. Furthermore, loss-of-function of cul-4 ectopically induces expression of negative regulators of eye development like Wg and Homothorax (Hth). During eye development, Wg is known to block the progression of a synchronous wave of differentiation referred to as Morphogenetic furrow (MF). In cul-4 loss-of-function background, expression of dpp-lacZ, a MF marker, is significantly downregulated. Our data suggest a new role of cul-4 in retinal differentiation. These studies may have significant bearings on our understanding of early eye development.

Inactivation of Hippo and cJun-N-terminal Kinase (JNK) signaling mitigate FUS mediated neurodegeneration in vivo

Amyotrophic Lateral Sclerosis (ALS), a late-onset neurodegenerative disorder characterized by the loss of motor neurons in the central nervous system, has no known cure to-date. Disease causing mutations in human Fused in Sarcoma (FUS) leads to aggressive and juvenile onset of ALS. FUS is a well-conserved protein across different species, which plays a crucial role in regulating different aspects of RNA metabolism. Targeted misexpression of FUS in Drosophila model recapitulates several interesting phenotypes relevant to ALS including cytoplasmic mislocalization, defects at the neuromuscular junction and motor dysfunction. We screened for the genetic modifiers of human FUS-mediated neurodegenerative phenotype using molecularly defined deficiencies. We identified hippo (hpo), a component of the evolutionarily conserved Hippo growth regulatory pathway, as a genetic modifier of FUS mediated neurodegeneration. Gain-of-function of hpo triggers cell death whereas its loss-of-function promotes cell proliferation. Downregulation of the Hippo signaling pathway, using mutants of Hippo signaling, exhibit rescue of FUS-mediated neurodegeneration in the Drosophila eye, as evident from reduction in the number of TUNEL positive nuclei as well as rescue of axonal targeting from the retina to the brain. The Hippo pathway activates c-Jun amino-terminal (NH₂) Kinase (JNK) mediated cell death. We found that downregulation of JNK signaling is sufficient to rescue FUS-mediated neurodegeneration in the Drosophila eye. Our study elucidates that Hippo signaling and JNK signaling are activated in response to FUS accumulation to induce neurodegeneration. These studies will shed light on the genetic mechanism involved in neurodegeneration observed in ALS and other associated disorders.

A Positive Feedback Loop of Hippo- and c-Jun-Amino-Terminal Kinase Signaling Pathways Regulates Amyloid-Beta-Mediated Neurodegeneration

Alzheimer's disease (AD, OMIM: 104300) is an age-related disorder that affects millions of people. One of the underlying causes of AD is generation of hydrophobic amyloid-beta 42 (Aβ42) peptides that accumulate to form amyloid plaques. These plaques induce oxidative stress and aberrant signaling, which result in the death of neurons and other pathologies linked to neurodegeneration. We have developed a Drosophila eye model of AD by targeted misexpression of human Aβ42 in the differentiating retinal neurons, where an accumulation of Aβ42 triggers a characteristic neurodegenerative phenotype. In a forward deficiency screen to look for genetic modifiers, we identified a molecularly defined deficiency, which suppresses Aβ42-mediated neurodegeneration. This deficiency uncovers hippo (hpo) gene, a member of evolutionarily conserved Hippo signaling pathway that regulates growth. Activation of Hippo signaling causes cell death, whereas downregulation of Hippo signaling triggers cell proliferation. We found that Hippo signaling is activated in Aβ42-mediated neurodegeneration. Downregulation of Hippo signaling rescues the Aβ42-mediated neurodegeneration, whereas upregulation of Hippo signaling enhances the Aβ42-mediated neurodegeneration phenotypes. It is known that c-Jun-amino-terminal kinase (JNK) signaling pathway is upregulated in AD. We found that activation of JNK signaling enhances the Aβ42-mediated neurodegeneration, whereas downregulation of JNK signaling rescues the Aβ42-mediated neurodegeneration. We tested the nature of interactions between Hippo signaling and JNK signaling in Aβ42-mediated neurodegeneration using genetic epistasis approach. Our data suggest that Hippo signaling and JNK signaling, two independent signaling pathways, act synergistically upon accumulation of Aβ42 plaques to trigger cell death. Our studies demonstrate a novel role of Hippo signaling pathway in Aβ42-mediated neurodegeneration.

Exploring the efficacy of natural products in alleviating Alzheimer's disease

Alzheimer’s disease (hereafter AD) is a progressive neurodegenerative disorder that affects the central nervous system. There are multiple factors that cause AD, viz., accumulation of extracellular Amyloid-beta 42 plaques, intracellular hyper-phosphorylated Tau tangles, generation of reactive oxygen species due to mitochondrial dysfunction and genetic mutations. The plaques and tau tangles trigger aberrant signaling, which eventually cause cell death of the neurons. As a result, there is shrinkage of brain, cognitive defects, behavioral and psychological problems. To date, there is no direct cure for AD. Thus, scientists have been testing various strategies like screening for the small inhibitor molecule library or natural products that may block or prevent onset of AD. Historically, natural products have been used in many cultures for the treatment of various diseases. The research on natural products have gained importance as the active compounds extracted from them have medicinal values with reduced side effects, and they are bioavailable. The natural products may target the proteins or members of signaling pathways that get altered in specific diseases. Many natural products are being tested in various animal model systems for their role as a potential therapeutic target for AD, and to address questions about how these natural products can rescue AD or other neurodegenerative disorders. Some of these products are in clinical trials and results are promising because of their neuroprotective, anti-inflammatory, antioxidant, anti-amyloidogenic, anticholinesterase activities and easy availability. This review summarizes the use of animal model systems to identify natural products, which may serve as potential therapeutic targets for AD.

Household food insecurity is associated with low interferon-gamma levels in pregnant Indian women

SETTING

Over 20% of tuberculosis (TB) cases during pregnancy occur in India.

OBJECTIVE

To determine the association between household food insecurity and interferon-gamma (IFN-γ) levels in pregnancy.

DESIGN

Pregnant women in India were administered the Household Food Insecurity Access Scale (HFIAS) questionnaire and underwent an IFN-γ release assay. Logistic regression was used to identify factors associated with food insecurity.

RESULTS

Of 538 women, 60 (11%) had household food insecurity, 47 (78%) of which were moderate or severe food insecure. After mitogen stimulation, moderate or severe food insecure women had a median IFN-γ concentration of 4.2 IU/ml (IQR 2.2-9.8) vs. 8.4 IU/ml (IQR 3.0-10) in women with no or mild food insecurity (P = 0.03). In multivariate analysis, higher IFN-γ concentrations were associated with human immunodeficiency virus infection (OR 1.3, 95%CI 0.51-2.1, P = 0.001), and inversely associated with moderate or severe food insecurity (OR -1.6, 95%CI -2.9 to -0.27, P = 0.02) and the number of adults in the household (OR -0.08, 95%CI -0.16 to -0.01, P = 0.03). There was no association between food insecurity and IFN-γ response to Mycobacterium tuberculosis antigen.

CONCLUSION

Food insecurity in pregnancy is associated with low IFN-γ levels. There was no association between food insecurity and IFN-γ response to M. tuberculosis antigen, but our study was underpowered to detect this outcome.

Tribocatalytic behaviour of a TiO2 atmospheric plasma spray (APS) coating in the presence of the friction modifier MoDTC: a parametric study

Recent engine design and emission trends have led to the commercial use of Atmospheric Plasma Spray (APS) coatings for cylinder liner applications like the TiO₂ APS coating. It was shown in our previous work that this type of coating showed better friction results compared to steel lubricated with MoDTC. To further investigate this feature, a parametric study was carried out involving the effect of MoDTC concentration, test temperature, Hertzian contact pressure and the change of counterpart materials from steel balls to ceramic balls (Al₂O₃ and ZrO₂). Ball-on-flat tribotests were carried out on a reciprocating (ball-on-flat) tribometer lubricated with base oil containing MoDTC. Results show that for all the test conditions used including the concentration of MoDTC, test temperature and the contact pressure, lower friction and wear is observed for the TiO₂ APS coating compared to reference steel. To explain the low friction behavior, tribofilm compositions were investigated and it was observed that MoS₂ is always formed in the case of TiO₂ APS with no oxysulphide species. For the reference steel, MoO_xS_y species are mainly detected in the tribofilms. XPS analyses performed on TiO₂ APS flats when the counterpart material was changed from steel balls to ceramic balls suggested the formation of MoS₂ (Mo in +iv oxidation state) and Mo–C (Mo in +iv or +ii oxidation state) species with a negligible amount of MoO₃ (Mo in +vi oxidation state). It was also shown that a significant amount of molybdenum atoms inside the tribofilm, originating from MoDTC (Mo in +v oxidation state) were reduced in the tribological contact. A mechanism for the decomposition of MoDTC on the basis of tribocatalytic behaviour hypothesized in our previous work was proposed and discussed.

Tribocatalytic behaviour of TiO₂ APS coatings in presence of MoDTC additive under boundary lubrication conditions – decomposition mechanism

Impact of maternal hepatitis B virus coinfection on mother-to-child transmission of HIV

OBJECTIVES

Despite high hepatitis B virus (HBV) endemicity in various resource-limited settings (RLSs), the impact of maternal HIV/HBV coinfection on infant health outcomes has not been defined. We aimed to assess the prevalence of HBV coinfection among HIV-infected pregnant women and its impact on HIV transmission and infant mortality.

METHODS

In this study, the seroprevalence of HBV coinfection was determined among HIV-infected pregnant women enrolled in the Six-Week Extended-Dose Nevirapine (SWEN) India trial. The impact of maternal HIV/HBV coinfection on mother-to-child transmission (MTCT) of HIV and infant mortality was assessed using univariate and multivariate logistic regression analysis.

RESULTS

Among 689 HIV-infected pregnant Indian women, 32 (4.6%) had HBV coinfection [95% confidence interval (CI) 3.4%, 5.3%]. HBV DNA was detectable in 18 (64%) of 28 HIV/HBV-coinfected women; the median HBV viral load was 155 copies/mL [interquartile range (IQR) < 51-6741 copies/mL]. Maternal HIV/HBV coinfection did not increase HIV transmission risk [adjusted odds ratio (aOR) 1.06; 95% CI 0.30, 3.66; P = 0.93]. Increased odds of all-cause infant mortality was noted (aOR 3.12; 95% CI 0.67, 14.57; P = 0.15), but was not statistically significant.

CONCLUSIONS

The prevalence of active maternal HBV coinfection in HIV-infected pregnant women in India was 4.6%. HIV/HBV coinfection was not independently associated with HIV transmission.

Peripherally inserted central catheter tip position and risk of associated complications in neonates

OBJECTIVE

To characterize the relationship between peripherally inserted central catheters (PICC) tip positions and associated complications in neonates.

STUDY DESIGN

Catheter tip position for 319 infants was classified into superior vena cava (SVC, n=131), inferior vena cava (IVC, n=72), brachiocephalic (BC, n=59), midclavicular (MC, n=49) or iliac. Duration of catheter stay and complication profile was compared between central (SVC/IVC) vs non-central PICC, and between SVC vs IVC, SVC vs BC and SVC vs MC. Kaplan-Meier survival analysis and regression models were used.

RESULT

Overall length of catheter stay was similar between central and non-central group. Non-central catheters (n=116) had higher complication rates (47 vs 29%; P=0.001), non-elective removals (45 vs 27%; P=0.002) and shorter time to complication (6.2 vs 11.4 days; P=0.043). This difference was primarily due to the complications encountered in MC group, which had the highest rate of infiltration (P<0.001) and mechanical complications while outcomes were similar among other subgroups. Interestingly, catheter survival probability was similar in all groups for first 4 days. Rate and types of blood stream infections were not related to catheter tip position.

CONCLUSION

Non-central PICCs are associated with higher rates of infiltration and mechanical complications when the tip is in MC region. BC catheters may have comparable outcomes to SVC in neonates. A careful risk-benefit analysis is warranted when MC catheters are used in neonates.

Standardization of fungal polymerase chain reaction for the early diagnosis of invasive fungal infection

BACKGROUND

An early initiation of antifungal therapy in invasive fungal infections (IFIs) is critical in reducing the high mortality rate. Current diagnosis of fungal infection relies on microscopy, culture, antigen, antibody specific tests and histological diagnosis. However, these tests either lack sensitivity or specificity. There is thus the need for a rapid, specific and accurate diagnostic method.

OBJECTIVE

The aim of our study was to establish PCR for the rapid detection of Candida and Aspergillus species in clinical specimens with improved sensitivity and specificity.

MATERIALS AND METHODS

A total of 71 proven cases of IFI (confirmed by culture) were collected. A total of 15 healthy, 15 patients suffering from bacterial sepsis and 15 patients with HIV, HBV viral infections were included as controls. Clinical specimens were subjected to a standardized nested amplification to produce Round I (504 bp) and Round II (150 bp) amplicons. Restriction digestion was performed on these products for further identification.

RESULTS

Analytical sensitivity was determined using 10⁶-10 CFU/ml of cell suspension. The lower detection limit of the assay was 10 CFU/ml of blood. This test was 100% sensitive and specific with a positive predictive value of 100% and a negative predictive value of 96.7%.

CONCLUSION

The assay was found to be effective for the rapid detection of Candida and Aspergillus in clinical specimens.

Development and validation of a HPTLC method for Estimation of Duloxetine Hydrochloride in Bulk Drug and in Tablet Dosage Form

Duloxetine hydrochloride is a potent dual reuptake inhibitor of serotonin and norepinephrine used to treat major depressive disorders. The present work describes a simple, precise and accurate HPTLC method for its estimation as bulk and in tablet dosage form. The chromatographic separation was carried out on precoated silica gel 60 F254 aluminium plates using mixture of chloroform:methanol (8:1 v/v) as mobile phase and densitometric evaluation of spots was carried out at 235 nm using Camag TLC Scanner-3 with win CAT 1.3.4 version software. The experimental parameters like band size of the spot applied, chamber saturation time, solvent front migration, slit width etc. were critically studied and optimum conditions were evolved. The drug was satisfactorily resolved with Rf value 0.11+/-0.01. The accuracy and reliability of the proposed method was ascertained by evaluating various validation parameters like linearity (40-200 ng/spot), precision (intra-day RSD 0.46-0.75%, inter-day RSD 0.46-1.59%), accuracy (98.72+/-0.20) and specificity according to ICH guidelines. The proposed method can analyse ten or more formulation units simultaneously on a single plate and provides a faster and cost-effective quality control tool for routine analysis of duloxetine hydrochloride as bulk drug and in tablet formulation.

Genetic Approaches Identify Differential Roles for α4β2*Nicotinic Receptors in Acute Models of Antinociception in Mice

The effects of nicotine on the tail-flick and hot-plate tests were determined to identify nicotinic receptor subtypes responsible for spinally and supraspinally mediated nicotine analgesia in knockin mice expressing hypersensitive alpha(4) nicotinic receptors (L9'S), in seven inbred mouse strains (C57BL/6, DBA/2, A/2, CBA/2, BALB/cByJ, C3H/HeJ, and 129/SvEv), and in two F1 hybrids (B6CBAF1 and B6D2F1). L9'S heterozygotes were approximately 6-fold more sensitive to the antinociceptive effects of nicotine than the wild-type controls in the hot-plate test but not in the tail-flick assay. Large differences in the effects of nicotine were also observed with both tests for the seven mouse strains. A/J and 129 mice were 6- to 8-fold more sensitive than CBA and BALB mice. In addition, B6CBAF1 hybrid mice were even less sensitive than CBA mice. Nicotinic binding sites were measured in three spinal cord regions and the hindbrain of the inbred strains. Significant differences in cytisine-sensitive, high affinity [(125)I]epibatidine binding site levels (alpha(4)beta(2)(*) subtypes), but not in (125)I-alpha-bungarotoxin binding (alpha(7)(*) subtypes), were observed. Significant negative correlations between cytisine-sensitive [(125)I]epibatidine binding and nicotine ED(50) for both tests were noted. Our results indicate that alpha(4)beta(2)(*) acetylcholine nicotinic receptors (nAChR) are important in mediating nicotine analgesia in supraspinal responses, while also showing that alpha(4)beta(2)(*)-nAChR and at least one other nAChR subtype appear to modulate spinal actions.

Soleus motor neuron excitability before and after standing

H-reflexes have been used to assess the effect of various postures on the excitability of the soleus motor neuronal pool. The purpose of this study was to determine if the excitability of the motor neuron pool, measured via H-reflexes in a seated position, change after a standing protocol in able-bodied individuals. We hypothesized that the excitability of the motor neuronal pool is minimally affected by the standing protocol leading to a reproducible H-reflex. Ten healthy individuals (height = 69.05+/-2.27 inches, weight = 161.7+/-22.44 lbs, age = 27.7+/-7.0 years) participated in the study. Soleus H-reflex recruitment curves were established before and after a standing protocol in a seated position. The standing protocol involved 12 minutes of active upright standing interspersed with 10 minutes of relaxed passive standing in a standing frame, similar to a protocol currently used for spinal cord injured subjects. The maximum M-waves and H-reflex amplitudes were not systematically changed before and after standing. There was also a strong agreement between the H-reflexes and M-waves measured before and after standing (ICC = 0. 99 and .96, respectively). We conclude that the H-reflexes measured in this study were reproducible, indicating that standing had no long lasting effect on the motor neuronal pool excitability. The findings support that the method discussed in this report is appropriate to assess the effects of electrically induced standing on motor neuron pool excitability in individuals with spasticity from spinal cord injury.

Using active management of labor and vaginal birth after previous cesarean delivery to lower cesarean delivery rates: aA 10-year experience

OBJECTIVE

Our objective was to analyze the statistics on cesarean delivery rates and the factors that have led to a reduction in these rates.

STUDY DESIGN

A retrospective analysis was done of delivery statistics from a 10-year period, January 1, 1989, to December 31, 1998. We investigated the changes made in the methods of delivery during the study period. The data were divided into 1-year periods and analyzed by chi(2) tables.

RESULTS

The overall cesarean delivery rate decreased from 16.59% to 10.92%; the primary cesarean delivery rate decreased from 9.22% to 7.11% and the repeated cesarean delivery rate from 7.37% to 3.81%. All these decreases were statistically significant. An increase in the rate of active management of labor by increasing oxytocin use and encouraging a trial of labor after previous cesarean delivery was also statistically significant. No changes in the outcome were observed in terms of neonatal morbidity and mortality rates.

CONCLUSION

We found that our working plan for management of labor and delivery yielded and maintained a successful decline in the cesarean delivery rates without any negative effect on neonatal or maternal mortality rates. This low rate was maintained for a 10-year period.

Prenatal diagnosis of fetal abdominal lymphangioma by ultrasonography

We present a case of abdominal lymphangioma in a fetus together with a review of the literature. Diagnosis was made at 20 weeks' gestation by antenatal ultrasonography. In keeping with other reports, the lesion was located on the left and serial ultrasonography demonstrated rapid growth with extension into the lower extremity.

Point mutant mice with hypersensitive alpha 4 nicotinic receptors show dopaminergic deficits and increased anxiety

Knock-in mice were generated that harbored a leucine-to-serine mutation in the alpha4 nicotinic receptor near the gate in the channel pore. Mice with intact expression of this hypersensitive receptor display dominant neonatal lethality. These mice have a severe deficit of dopaminergic neurons in the substantia nigra, possibly because the hypersensitive receptors are continuously activated by normal extracellular choline concentrations. A strain that retains the neo selection cassette in an intron has reduced expression of the hypersensitive receptor and is viable and fertile. The viable mice display increased anxiety, poor motor learning, excessive ambulation that is eliminated by very low levels of nicotine, and a reduction of nigrostriatal dopaminergic function upon aging. These knock-in mice provide useful insights into the pathophysiology of sustained nicotinic receptor activation and may provide a model for Parkinson's disease.

Failure of autoresuscitation in weanling mice: significance of cardiac glycogen and heart rate regulation

"Autoresuscitation" (AR) is the spontaneous recovery from hypoxic apnea by gasping. We examined aspects of heart function in two situations: 1) the maturationally acquired failure of AR that is characteristic of SWR, but not BALB/c, weanling mice and 2) AR failure in BALB/c mice induced by repeated exposures to anoxia. We determined maturational changes in heart and liver glycogen. Unlike liver glycogen levels, heart glycogen levels in SWR mice differed from those in BALB/c mice. They were consistently much lower throughout maturation and reached a nadir during the brief period when SWR weanling mice are vulnerable to AR failure. Also, rate of cardiac glycogen utilization in vulnerable SWR mice was lower than that of same-aged BALB/c mice and was nil during the latter one-half of the gasping stage when heart function is critical for AR success. Therefore, because glycogen utilization reflects cardiac work, heart failure could explain AR failure in SWR weanlings. Additionally, the increase in hypoxic heart rate that occurs with maturation is developmentally delayed in SWR mice, and this may contribute to their AR failure. Cardiac glycogen was not fully depleted in BALB/c mice during repeated anoxic exposures, indicating other reasons for AR failure. We view these findings as a potential model for the age-related peak in incidence of sudden infant death syndrome.

Pyrexia of unknown origin, the age-old dilemma

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Obsessive-compulsive symptoms in chronic schizophrenia: a new idea or an old belief?

Obsessive-compulsive (OC) symptoms during the course of schizophrenia have been reported, yet the incidence and significance of this finding is still unclear. This study was undertaken to determine the prevalence of OC symptoms among chronic schizophrenic patients and to systematically identify them. 101 patients satisfying DSM-IV diagnosis of chronic schizophrenia were assessed for OC symptoms. All patients were also rated on the Yale-Brown Obsessive Compulsive Scale for the severity of their symptoms. The study revealed that 26.7% of the chronic schizophrenic patients had significant OC symptoms with a high prevalence in the age group below 35 years. OC symptoms were more severe in patients with duration of illness more than 5 years. The OC symptoms were more prevalent among paranoid schizophrenics with the frequent obsessions being that of contamination, sexual and aggressive thoughts and frequent compulsion was need to ask or confess.

Channel gating governed symmetrically by conserved leucine residues in the M2 domain of nicotinic receptors

In nicotinic acetylcholine receptors (nAChR), as well as glycine, GABAA (gamma-aminobutyric acid), serotonin (5-HT3), and GluCl glutamate receptors, a leucine residue at the approximate midpoint of the M2 transmembrane domain (the 9' position) is conserved across most known subunits. Structural data for the nAChR suggest that the Leu 9' residues occupy a 'kink' in each of the five M2 helices and point into the closed channel; in the opening step, the M2 helices rotate so that Leu 9' side chains no longer occlude the conduction pathway. Mutation of Leu 9' to one of several other residues slows desensitization and increases sensitivity to agonist. We have exploited the alpha 2 beta gamma delta stoichiometry of muscle nAChR to express receptors with ms* = 0 to 5 Leu 9'Ser mutated subunits. Strikingly, each Leu 9'Ser mutation shifts the dose-response relation for ACh to the left by approximately 10-fold; a nAChR with ms* = 4 is 10(4)-fold more sensitive than the wild type. The results suggest that each of the five Leu 9' residues participates independently and symmetrically in a key step in the structural transition between the closed and open states.

DMSO resolves certain compressions and signal dropouts in fluorescent dye labeled primer-based DNA sequencing reactions

Automated base calling algorithms are more sensitive to the quality of the DNA sequencing data than are the labor intensive visual methods of base calling. To improve this quality, data from DNA sequencing reactions have been compared in order to determine the effects of the inclusion of dimethyl sulfoxide (DMSO). Inclusion of 10% DMSO into the reaction cocktail resolves at least one type of sequence compression. This compression may be due to the lack of ability in T7 DNA polymerase to read through certain sequences correctly. The poor quality of these data is seen as radioactive bands or fluorescent signal peaks that have an abnormal alignment, either in the wrong order or as single bands/peaks. The inclusion of DMSO also resolves sequences where the peak signal is absent or severely diminished, leading to a "gap" in the chromatogram profile. DMSO is better than deaza-dITP for resolving certain compressions. Addition of DMSO is a cheaper and more efficient method for high-throughput DNA sequencing than repeating reactions with base analogs.

Organization, sequence, and function of 34.5 kb of genomic DNA encompassing several murine T-cell receptor alpha/delta variable gene segments

A cosmid-bearing murine genomic DNA, encompassing several T-cell receptor variable alpha/delta gene segments, has been sequenced using shotgun DNA cloning methodology coupled with fluorescence-based high-through-put DNA sequencing technology. This region, spanning 34.5 kb, contains a pseudogene V alpha gene segment (psi V alpha 16.1), a V delta gene segment (V delta 2), and a variable gene segment that has been reported to be expressed with both C alpha (V alpha 6) and C delta (V delta 3). Therefore, this cosmid is the ideal vehicle for examining the possible control sequences that may be involved in determining whether a V gene segment associates with either C alpha or C delta. Polymerase chain reaction experiments demonstrate that the two functional variable gene segments (V delta and V alpha/delta) are expressed individually with both C alpha and C delta genes as mRNA, indicating a permissiveness in their expression patterns. In addition, a variety of genomic sequence-related features have been identified.