Immunosenescence of human NK cells: effects on tumor target recognition, lethal hit and interferon sensitivity.

Previous results from this laboratory have shown the preservation of non-MHC-restricted, constitutive oncolytic activity of human peripheral blood NK cells in the elderly as assessed by the chromium release assay which quantitates the lytic endpoint at the cell population level. We have now addressed this senescence-related change at single-cell level using 101 blood samples. Both the efficiency of the initial tumor target binding step i.e., recognition of K562, the NK-sensitive erythroleukemia cell line, as well as the ability of NK cells to deliver lethal hit are highly conserved during healthy aging. In fact, the elderly exhibit a statistically significant, moderately higher frequency of active killers among circulating lymphocytes. Analyzed in another way, a majority of "high NK responders" were found to be older donors, while none in the "low NK responders" group were > 70 years old. Gamma interferon, a gene product as well as an autocrine activator of NK cells, is effective in converting non-lytic "pre-NK" cells to active killers at single-cell level. This in vitro cytokine sensitivity of NK cells is unaltered during immune senescence. The intactness of the NK cell's capacity to be modulated may be vital in both tumor resistance and host viral defenses of aged humans.     

Central brain herniation in shunted Dandy walker cyst

Introduction

Dandy–Walker Syndrome (DWS) is a constellation of congenital anomalies of the central nervous system consisting of cerebellar vermis hypoplasia or agenesis, cystic dilatation of the fourth ventricle, enlarged posterior fossa, and a high tentorium. Hydrocephalus is a common occurrence in DWS and its treatment varies between shunting-ventriculoperitoneal or cystoperitoneal or both, endoscopic cyst fenestration, and third ventriculostomy. Chronic cerebral herniation is a known complication of treatment in DWS; however, we present an unusual case of central brain herniation.

Case report

A 2 year old boy with shunted DWS presented with status epilepticus. Initial CT brain scan showed no increase in ventricle or cyst size; however, tapping the shunt reservoir did not yield any CSF prompting a shunt revision. Postoperatively, he was very slow to wake and subsequently experienced an episode of fixed pupils and extensor posturing. MRI brain demonstrated severe herniation of both thalami through the tentorium.

Conclusion

This child had chronic central brain herniation (CCBH) secondary to the shunting of his cyst. To our knowledge, this is the first case of CCBH following treatment of DW cyst     

<Emphasis Type="Italic">Rhizobium</Emphasis> Mutant Deficient in Mineral Phosphate Solubilization Activity Shows Reduced Nodulation and Plant Growth in Green Gram

The aim of the present study was to understand the mineral phosphate solubilization (MPS) in Rhizobium sp. MR-54 (MPS⁺) by using forward genetic approach and its effect on nodulation as well as nitrogen accumulation on green gram. Tn5 mutants (MPS^?) were generated from the MPS⁺ strain by Tn5 mutagenesis. Screening 1,603 colonies of MR-54::Tn5 resulted in identification of those mutants which failed to show any solubilization zone up to 72 h after incubation on Tri-calcium phosphate medium (TCP). pH drops and Pi release were highly correlated up to 15 days after incubation in TCP broth. Gluconic acid was detected in the culture supernatants of MPS⁺ isolates through thin layer chromatography indicating the presence of direct oxidation pathway in MR-54 strain. Detailed characterization of mutants was carried out for related properties like colony morphology, Pi release and pH change in TCP broth, organic acid production, surface characteristics and plant growth promoting ability etc. Mutants deficient in MPS showed reduced nodulation and nitrogen accumulation in green gram under green house conditions in leonard jar apparatus over the wild strain indicating the MPS by Rhizobium being involved in nodulation, nitrogen accumulation and plant growth.     

A 4-year retrospective study of mandibular fractures in a South Indian city

The medical records of 238 patients treated for mandibular fractures at Sri Ramachandra Dental College and Hospital, India, over a period of 4 years were reviewed. Of the total 238 patients with mandibular fractures, 81% were males, and 19% were females. The majority of the patients were 21 to 30 years of age. Road traffic accidents, especially people traveling on motorcycles, accounted for 73% of all patients, with a high prevalence during the month of September and on Saturdays. The most common area of fracture was in the parasymphysis region (35.2%) followed by the condyle region (22.6%).     

From the Cover: Leukocyte immunoglobulin-like receptor B1 is critical for antibody-dependent dengue

Viruses must evade the host innate defenses for replication and dengue is no exception. During secondary infection with a heterologous dengue virus (DENV) serotype, DENV is opsonized with sub- or nonneutralizing antibodies that enhance infection of monocytes, macrophages, and dendritic cells via the Fc-gamma receptor (FcγR), a process termed antibody-dependent enhancement of DENV infection. However, this enhancement of DENV infection is curious as cross-linking of activating FcγRs signals an early antiviral response by inducing the type-I IFN-stimulated genes (ISGs). Entry through activating FcγR would thus place DENV in an intracellular environment unfavorable for enhanced replication. Here we demonstrate that, to escape this antiviral response, antibody-opsonized DENV coligates leukocyte Ig-like receptor-B1 (LILRB1) to inhibit FcγR signaling for ISG expression. This immunoreceptor tyrosine-based inhibition motif-bearing receptor recruits Src homology phosphatase-1 to dephosphorylate spleen tyrosine kinase (Syk). As Syk is a key intermediate of FcγR signaling, LILRB1 coligation resulted in reduced ISG expression for enhanced DENV replication. Our findings suggest a unique mechanism for DENV to evade an early antiviral response for enhanced infection.Despite long-lived serotype-specific immunity upon initial infection, predicted global prevalence of dengue now surpasses World Health Organization estimates by more than threefold with 390 million cases annually (1). Furthermore, the risk of severe disease is augmented by cross-reactive or subneutralizing levels of antibody (2, 3), which opsonize dengue virus (DENV) to ligate Fc-gamma receptor (FcγR) for entry into monocytes, macrophages, and dendritic cells, a phenomenon known as antibody-dependent enhancement (ADE) of DENV infection (4, 5). The resultant greater viral burden leads to increased systemic inflammation that precipitates plasma leakage, a hallmark of dengue hemorrhagic fever (6). However, ligation of the activating FcγRs by immune complexes has been shown to induce type-I IFN stimulated genes (ISGs), independent of autocrine or paracrine IFN activity, unless the inhibitory FcγRIIB is coligated (7). We and others reported recently that coligation of FcγRIIB by DENV immune complexes requires high antibody concentration, and such coligation inhibited the entry of DENV immune complexes into monocytes (8, 9). At low antibody concentrations where ADE occurs, the inhibitory FcγRIIB is not coligated (9). Ligation of the activating FcγRs by DENV opsonized with subneutralizing levels of antibody would thus induce the expression of ISGs and hinder DENV replication (10). Here, we demonstrate that DENV employs a unique evasive mechanism by coligating LILRB1 to down-regulate the early antiviral responses triggered by activating FcγRs for ADE.     

Glaucoma and optical coherence tomography changes in migraine: A comparative cross-sectional study

Purpose:To study the prevalence of glaucoma among adults with migraine and the effect of migraine on peripapillary retinal nerve fiber layer (pRNFL) and central macular thickness (CMT) using optical coherence tomography (OCT) compared to those without migraine headache, i.e. in tension-type headache (TTH) and normal group.Methods:One hundred and eleven patients (222 eyes) were recruited in three groups. migraine, TTH, and normal subjects visiting hospital outpatient services. After noting demographic details and pertinent history, ophthalmological evaluation including optic disc for glaucomatous changes along with computerized visual field testing and OCT for pRNFL thickness and CMT was performed in all eyes. Continuous variables were compared using ANOVA or Kruskal–Wallis test, while categorical variables including the association of glaucoma with migraine were analyzed using Chi-square or Fisher’s exact test.Results:Prevalence of glaucoma in migraine group (12.2%) was more than in comparison groups (6.8% in TTH, 4.1% in normal) which was however not significant (Fisher’s exact P = 0.207). Average pRNFL thickness (103.59 ± 12.82 μm) and thickness in nasal (90.49 ± 19.19 μm) and temporal quadrants (70.58 ± 16.13 μm) and CMT (213.78 ± 19.81 μm) were significantly reduced (ANOVA P < 0.05) in migraine patients when compared to the other groups and this was independent of the presence of glaucoma.Conclusion:Prevalence of glaucoma is not significantly higher in migraine patients. However, migraine causes thinning of retinal layers on OCT that is statistically significant.     

Disseminated and disfiguring molluscum contagiosum in a child

We report widely disseminated and disfiguring lesions of molluscum contagiosum occurring in a 4-year-old girl secondary to a primary immunodeficiency disorder. The child, born of consanguineous parents, had multiple, asymptomatic, raised, skin-colored and whitish lesions since 2 years of age. On physical examination she had growth retardation features with grade II protein energy malnutrition. Cutaneous examination revealed numerous, widespread, skin-colored to translucent, firm, umbilicated papules of varying sizes (pinpoint to larger than 10 mm). They were distributed bilaterally over all four limbs, including the dorsum of the hands and feet, trunk, face (including lips), eyelids, auriculae, and perineal and gluteal areas. In places, they were linearly disposed and had coalesced to form plaques. A biopsy specimen from a representative skin lesion (arm) demonstrated lobulated epidermal growth consisting of keratinocytes with large intracytoplasmic eosinophilic inclusion bodies and a central crater. These findings were consistent with the diagnosis of molluscum contagiosum. Topical therapies with phenol and trichloroacetic acid were ineffective The child succumbed to a fulminant systemic infection at home, 2 months after discharge from the hospital. The extent and distribution of molluscum contagiosum in our patient was remarkably vivid and has been hitherto reported only rarely.     

Pattern of pediatric dermatoses in a referral center in South India

This study was undertaken to determine the pattern of dermatoses in children in south India. All children <14 years presenting to us between May 2001 and June 2002 were recruited. A total of 2100 children (males -995; females- 1105) with 2144 dermatoses were recorded. Infections and infestations were the most common dermatoses (54.5%) followed by dermatitis and eczema (8.6%), pigmentary disorders (5.7%), insect bite reaction (5.27%), hair and nail disorders (5.2%), miliaria (4.1%), nutritional deficiency disorders (2.8%), urticaria (2.5%), genetic disorders (2.1%), psoriasis (1.4%), collagen vascular disorders (0.5%), hemangiomas (0.5%), drug eruptions (0.3%), pityriasis rosea (0.2%) and others (5.8%). Pyodermas were the most common dermatoses (47.13%) followed by scabies (30.6%) amongst infections and infestations. Atopic dermatitis was noticed only in 3 patients. Insect bite reactions (papular urticaria) (5.27%) and miliaria (4.1%) were attributed to the tropical weather conditions in this coastal area. Genetic disorders including ichthyosis and palmoplantar keratoderma contributed to 2.1% of cases and could be due to the high incidence of consanguinous marriages in this society.