Amsha Ramburan

Myomegalin is a novel A-kinase anchoring protein involved in the phosphorylation of cardiac myosin binding protein C.

BackgroundCardiac contractility is regulated by dynamic phosphorylation of sarcomeric proteins by kinases such as cAMP-activated protein kinase A (PKA). Efficient phosphorylation requires that PKA be anchored close to its targets by A-kinase anchoring proteins (AKAPs). Cardiac Myosin Binding Protein-C (cMyBPC) and cardiac troponin I (cTNI) are hypertrophic cardiomyopathy (HCM)-causing sarcomeric proteins which regulate contractility in response to PKA phosphorylation.ResultsDuring a yeast 2-hybrid (Y2H) library screen using a trisphosphorylation mimic of the C1-C2 region of cMyBPC, we identified isoform 4 of myomegalin (MMGL) as an interactor of this N-terminal cMyBPC region. As MMGL has previously been shown to interact with phosphodiesterase 4D, we speculated that it may be a PKA-anchoring protein (AKAP).To investigate this possibility, we assessed the ability of MMGL isoform 4 to interact with PKA regulatory subunits R1A and R2A using Y2H-based direct protein-protein interaction assays. Additionally, to further elucidate the function of MMGL, we used it as bait to screen a cardiac cDNA library. Other PKA targets, viz. CARP, COMMD4, ENO1, ENO3 and cTNI were identified as putative interactors, with cTNI being the most frequent interactor.We further assessed and confirmed these interactions by fluorescent 3D-co-localization in differentiated H9C2 cells as well as by in vivo co-immunoprecipitation. We also showed that quantitatively more interaction occurs between MMGL and cTNI under β-adrenergic stress. Moreover, siRNA-mediated knockdown of MMGL leads to reduction of cMyBPC levels under conditions of adrenergic stress, indicating that MMGL-assisted phosphorylation is requisite for protection of cMyBPC against proteolytic cleavage.ConclusionsThis study ascribes a novel function to MMGL isoform 4: it meets all criteria for classification as an AKAP, and we show that is involved in the phosphorylation of cMyBPC as well as cTNI, hence MMGL is an important regulator of cardiac contractility. This has further implications for understanding the patho-aetiology of HCM-causing mutations in the genes encoding cMyBPC and cTNI, and raises the question of whether MMGL might itself be considered a candidate HCM-causing or modifying factor.

Pediatric Plasmablastic Lymphoma A Clinicopathologic Study

Plasmablastic lymphoma (PBL) is reported rarely in children. To date, 10 cases are documented in the English-language literature. This study, based on 13 biopsies from 11 HIV-positive children (9 males, 2 females), documents the clinicopathologic features of PBL. The CD4 count ranged from 9 to 800 cells/mm3. All biopsies demonstrated exclusive plasmablastic morphology; CD20 immunonegativity; and VS38c, EMA, CD31, MUM-1, CD45, and CD79a immunopositivity. B-cell monoclonality was confirmed in all biopsies. Of 3 biopsies subjected to FISH investigation, 2 had a t(8,14) translocation. Nine patients with follow-up details were treated exclusively with HAART (highly active antiretroviral therapy) or with combinations of HAART, chemotherapy, and radiotherapy. Seven patients died. PBL histomorphology, disease stage, and treatment modalities employed were not predictive of outcome. The survival of 2 stage 4 patients for 3 and 8 years each, managed on HAART, chemotherapy, and radiotherapy, however, may justify a role for combined therapeutic modalities for PBL.

Granulomas in acquired immunodeficiency syndrome-associated cutaneous Kaposi sarcoma: evidence for a role for Mycobacterium tuberculosis.

Background: Co‐lesional acquired immunodeficiency syndrome‐associated cutaneous Kaposi sarcoma (AIDS‐KS) and Mycobacterium tuberculosis‐associated granulomatous inflammation are undocumented.

Bartonella quintana-induced vulval bacillary angiomatosis.

Bacillary angiomatosis (BA) is an increasingly reported infection, mainly in patients with acquired immunodeficiency syndrome. Different epidemiological risk factors are associated with the transmission of the causative agents, Bartonella henselae and B. quintana. Vulval BA is described rarely. Two patients presented with a vulval mass (Patient 1) and a verrucous vulval growth (Patient 2), which were diagnosed clinically as tuberculosis and carcinoma, respectively. Patient 1 also had pulmonary tuberculosis and Kaposi sarcoma. Biopsy of the vulval lesions confirmed BA, characterized by a multilobular proliferation of blood vessels that were lined by epithelioid endothelial cells. There were prominent intervascular neutrophils, karyorrhectic debris, and clumps of paravascular argyrophilic organisms. The biopsy from Patient 1 was deep dermal/subcutaneous in location and displayed foci of confluent suppuration. There was florid pseudoepitheliomatous hyperplasia in the biopsy from Patient 2. Molecular investigations confirmed intralesional B. quintana, hitherto unreported in vulval BA, as the causative agent in both biopsies. On follow-up, Patient 2 had developed additional lesions in the vulva and thigh, but all her lesions and the vulval mass (Patient 1) responded to erythromycin treatment. Patient 1 succumbed to tuberculosis. Heightened recognition of BA underpins rapid and optimal clinicopathological diagnosis, even in uncommon locations. Identification of the causative Bartonella species is important for appropriate, interventive social management.

Vulval Involvement in Acquired Immunodeficiency Syndrome-AssociatedDisseminated Histoplasmosis

Background: Female genital tract, including vulval, histoplasmosis is reported rarely despite an increased propensity for cutaneous involvement by disseminated histoplasmosis (DH), even in patients with acquired immunodeficiency syndrome (AIDS). Methods: Sixteen year retrospective study investigating vulval involvement by histoplasmosis. Results: Of 239 patients with DH, 6 had vulval involvement and were confirmed to have HIV infection and AIDS. Seventeen biopsies (9 vulval, 8 extravulval) from these 6 patients form the study cohort. Patients 1 to 4 had simultaneous vulval (5) and extravulval (5) cutaneous biopsies. Eight cutaneous biopsies demonstrated diffuse dermal infiltration by histiocytes containing budding yeasts of H. capsulatum variant capsulatum (HCVC). A single thigh lesion demonstrated diffuse dermal karyorrhexis and myriad extracellular HCVC and a lymph node were diffusely effaced by histiocytes containing HCVC. Patient 5 had concomitant, co-lesional disseminated Kaposi sarcoma and HCVC infection. Patient 6 had 2 initial biopsies that demonstrated H. capsulatum variant duboisii (HCVD). Three biopsies of persistent facial and vulval plaques and a vulval ulcer, despite amphotericin treatment, confirmed HCVD, Cytomegalovirus and HCVD and Herpes simplex virus infection in each of the persistent lesions, respectively. Patients 2, 3 and 4 died before treatment was commenced. Patient 5 was lost to follow-up and did not receive any treatment. Patient 1 had resolution of DH following treatment with itraconazole. Persistent cutaneous lesions (Patient 6) healed with aciclovir and ganciclovir but uterine cervical squamous carcinoma was diagnosed 6 months later. Conclusion: Vulval involvement by histoplasmosis shares overlapping clinical features with many infections and tumors. Vulval biopsies are pivotal for diagnosis and allied therapeutic monitoring, particularly in the context of AIDSassociated co-morbid pathology.

Infantile donovanosis presenting as external auditory canal polyps: a diagnostic trap.

Two infants, 6 months and 4 months of age, presented with bilateral or unilateral external auditory canal polyps and otorrhea, respectively. Additional findings on examination included otitis media and mastoiditis. Tympanic membrane perforation was noted in one patient and a postauricular abscess in the other. Incisional biopsies of the polyps and abscess were reported as nonspecific mixed inflammation and abscess wall, respectively. There was a limited response to an empirical 5-day course of trimethoprim sulfamethoxazole. The children were referred to the academic hospital, and excision of the polyps and biopsies of the middle ear, mastoid, and postauricular abscess was undertaken. All the biopsies demonstrated donovanosis. Reappraisal of the initial incisional biopsies also confirmed donovanosis. Trimethoprim sulfamethoxazole was administered to both patients for 3 weeks, with resolution of the lesions. Subsequent investigations confirmed genital tract donovanosis, human immunodeficiency virus seropositivity, acquired immunodeficiency syndrome, and pulmonary tuberculosis in both mothers. Heightened awareness of the occurrence of donovanosis at unusual sites and improved recognition of the histomorphological features of the disease, especially in small and superficial biopsies, are pivotal not only for its correct diagnosis in extragenital cutaneous and extracutaneous locations but also for timely and adequate therapy and an improved infant and maternal outcome.

Cardiac myosin binding protein C, adrenergic stimulation and cardiac contractility

Myosin binding protein C remained a perplexing although integral component of the sarcomeric thick filament until the discovery that genetic defects in its corresponding gene is a frequent cause of hypertrophic cardiomyopathy. Basic science investigation subsequently revealed that it is one of the most potent regulators of cardiac contractility. Phosphorylation of its N-terminus upon adrenergic stimulation, causes increased order in myosin heads as well as increased ATPase activity, Fmax and Ca2+-sensitivity of contraction, while its dephosphorylation upon cholinergic stimulation or during low flow ischaemia leads to changes in the sarcomeric thick filament that diminish interaction between myosin heads and actin. This dynamic flux in phosphorylation upon adrenergic stimulation is not only crucial to normal cardiac function and structure, but also vital for protection against ischaemic injury. Genetically-driven deficiency or inadequacy in cMyBPC leads to severe cardiac dysfunction and structural changes, including cardiac hypertrophy and dilation, and particularly attenuates the adaptive increase in left ventricular contractility that follows on β-adrenergic stimulation or pressure overload, resulting in decreased systolic function, and reduced cardiac output.

Nodal Donovanosis as the Sentinel Clue to Acquired Immunodeficiency Syndrome

Abstract Objective: Donovanosis, caused by Calymmatobacterium granulomatis, is a recognized cause of genital ulcer disease. Extragenital donovanosis in acquired immunodeficiency syndrome (AIDS) and lymph nodes is documented rarely. The aim of this report is to highlight implications of lymph node involvement as the initial manifestation of donovanosis, especially in AIDS. Materials and methods: This is a retrospective clinicopathological 6 year study that reviewed the features of lymph node biopsies and patients presenting with nodal donovanosis. Results: Of a total of 198 patients with donovanosis, 4 patients with nodal disease were identified. Patient 1, on anti-tuberculous therapy for pulmonary tuberculosis for 2 weeks, developed subcutaneous nodules on her legs and left-sided inguinal lymphadenopathy. Biopsies confirmed erythema induratum and nodal donovanosis in the former and latter sites, respectively. Patients 2 and 3 presented with right-sided inguinal lymphadenopathy that simulated lymphoma. Lymph node biopsy confirmed donovanosis. Further examination on follow-up, confirmed ulcers on the cervix and penis, in patients 2 and 3, respectively. Biopsies of these genital ulcers demonstrated donovanosis in both patients. Patient 4 presented with a left-sided neck mass, biopsy of which confirmed nodal donovanosis. Subsequent biopsy of a pre-auricular ulcer and of the cervix confirmed donovanosis. HIV seropositivity and AIDS were confirmed in all patients. Patient 1 died of pulmonary tuberculosis while disease resolution was achieved in the others following 4-6 weeks of trimethoprim-sulfamethoxazole treatment. Conclusion: Heightened clinicopathological recognition of nodal donovanosis, lymph node biopsy and careful histomorphological assessment thereof are pivotal, not only for diagnostic confirmation of nodal donovanosis and its distinction from other common nodal infections, especially in the AIDS context, but also as a sentinel clue to genital donovanosis, HIV infection and AIDS.

The Adventitial Angioproliferation in Human Immunodeficiency Virus Associated Large Artery Vasculopathy is Not a Manifestation of Kaposi Sarcoma

Introduction: Human immunodeficiency virus-associated large artery vasculopathy (HIV-vasculopathy) is characterized by distinctive transmural microanatomical alterations, including adventitial angioproliferation, similar to that described in early cutaneous Kaposi sarcoma (KS). Human herpesvirus-8 (HHV8), the etiological agent of KS, is identifiable in tissue sections. The aim of this study was to investigate, based on HHV8-latent nuclear antigen-1 (HHV8-LNA-1) immunohistochemical and HHV8 polymerase chain reaction (PCR) testing, whether KS is the cause of the angioproliferation. Materials and Methods: Sections from 20 large arteries, ten each with HIV-associated occlusive and aneurysmal vasculopathy and ten biopsies with early cutaneous KS from 30 anti-retroviral therapy naive patients were appraised microscopically and subjected to HHV8-LNA-1 immunostaining. Arterial sections were also subjected to HHV8 PCR investigation with appropriate positive and negative controls. Results: The microscopic large arterial adventitial alterations included a dissecting proliferation of capillary-caliber vasculature, surrounded by mixed inflammation, microhemorrhages, hemosiderin and vasa vasorum intimomedial fibrosis, and hypertrophy. Ten vessels also demonstrated adventitial leukocytoclastic and lymphocytic vasculitis. Immunohistochemical and PCR detection of HHV8 was consistently negative. Skin biopsies of KS shared the vascular adventitial alterations, but vasculitis and thrombosis were absent. Endothelial and dermal spindle cells were immunopositive for HHV8. Conclusion: The adventitial angioproliferation in large arteries with HIV-vasculopathy is not a manifestation of KS. The exact roles of HIV, including interaction with co-infective agents and cellular and subcellular responses in the induction of vasculopathic and vasa vasorum abnormalities, including adventitial angioinflammatory alterations, require accelerated investigation for improved disease understanding and patient management.