Epidemiology and pathophysiology of vascular thrombosis in acclimatized lowlanders at high altitude: A prospective longitudinal study.

Background: Previous literature suggests that thrombosis is more common in lowlanders sojourning at high altitude (HA) compared to near-sea-level. Though the pathophysiology is partly understood, little is known of its epidemiology. To elucidate this, an observational prospective longitudinal study was conducted in healthy soldiers sojourning for months at HA. Methods: A total of 960 healthy male subjects were screened in the plains, of which 750 ascended, to altitudes above 15,000ft (4,472m). Clinical examination, haemogram, coagulogram, markers of inflammation and endothelial dysfunction, were studied at three time points during ascent and descent. The diagnosis of thrombosis was confirmed radiologically in all cases where a thrombotic event was suspected clinically. Subjects developing thrombosis at HA were labelled as Index Cases (ICs) and compared to a nested cohort of the healthy subjects (comparison group,(CG)) matched for altitude of stay. Findings: Twelve and three subjects, developed venous (incidence: 5,926/105 person-years) and arterial (incidence: 1,482/105 person-years) thrombosis at HA, respectively. The ICs had enhanced coagulation (FVIIa: p<0.001; FXa: p<0.001) and decreased levels of natural anticoagulants (thrombomodulin, p=0.016; tissue factor pathway inhibitor [TFPI]: p<0.001) and a trend to dampened fibrinolysis (tissue plasminogen activator tPA; p=0.078) compared to CG. ICs also exhibited statistically significant increase in the levels of endothelial dysfunction and inflammation markers (vascular cell adhesion molecule-1[VCAM-1], intercellular adhesion molecule-1 [ICAM-1], vascular endothelial growth factor receptor 3 [VEGFR-3], P-Selectin, CD40 ligand, soluble C-reactive protein and myeloperoxidase: p<0.001). Interpretation: The incidence of thrombosis in healthy subjects at HA was higher than that reported in literature at near sea-level. This was associated with inflammation, endothelial dysfunction, a prothrombotic state and dampened fibrinolysis. Funding: Research grants from the Armed Forces Medical Research Committee, Office of the Director General of Armed Forces Medical Services (DGAFMS) & Defence Research and Development Organization (DRDO), Ministry of Defence, India.

Morphological and molecular analyses of Tylodelphys spp. metacercaria (Trematoda: Diplostomidae) from the vitreous humour of two freshwater fish species, Channa gachua (Ham.) and Puntius sophore (Ham.).

Trematodes of family Diplostomatidae consists of a large and diverse group of parasites which have larval stages that are very important pathogens of wild and cultured freshwater fishes worldwide, can cause serious impacts. Our understanding of the diplostomids diversity, though, remains deficient and limited especially in India. In the present study, the morphology and molecular characterization of Tylodelphys spp. from the vitreous humour of eye, collected from two economically important food fish, dwarf snakehead Channa gachua (Perciformes: Channidae) and pool barb Puntius sophore (Cypriniformes: Cyprinidae) were described from Bijnor and Meerut, Uttar Pradesh (U.P.), India respectively. Tylodelphys spp. were characterized morphologically by light microscopy and SEM observations. Partial sequences of the ribosomal ITS1-5.8S-ITS2 gene cluster were also used for molecular identification of the species. Combined morphological and molecular analyses revealed the presence of three species of Tylodelphys: Tylodelphys sp. CG from C. gachua and Tylodelphys sp. PS 1, Tylodelphys sp. PS 2 from P. sophore respectively. This study demonstrated that molecular diversity of Tylodelphys spp. in Meerut, UP, India that may contribute to our knowledge of the diagnosis and taxonomy of diplostomids in fish.

Morphological and Molecular Characterization of Metacercaria of Tylodelphys (Digenea: Diplostomidae) from the Piscine Host, Mystus tengara from India.

The diversity and taxonomy of diplostomids infecting freshwater fishes of the Indian region are predominantly poorly known. Yet compared to other trematodes, identification and discrimination of diplostomid metacercaria are difficult using morphology and site of infection. The present study provides the first molecular study of a Tylodelphys sp. from India. Specimens of Tylodelphys were collected from the vitreous humor of the eyes and from the brains of siluriform fish, Mystus tengara (Siluriformes: Bagridae) from Hastinapur, Meerut (U.P.), India. Taxonomic studies were performed on the basis of morphological, morphometrical, and molecular analysis. The dissimilarities in morphological and sites of infection between 2 forms of Tylodelphys, designated as Tylodelphys sp. 1 and Tylodelphys sp. 2, suggested that the forms were different species but, after performing molecular analysis, we conclude that despite morphological differences both morphotypes are conspecific.

First report on molecular evidence of Tylodelphys cerebralis (Diplostomulum cerebralis) Chakrabarti, 1968 (Digenea: Diplostomidae) from snakehead fish Channa punctata.

Freshwater snakehead fish, Channa punctata (Perciformes: Channidae) from Meerut (U.P.), India were screened for infection with metacercaria from the eye (vitreous humor) and brain (cranial cavity) and were analyzed by molecular methods using PCR and sequencing of the complete internal transcribed spacers (ITS1-5.8S-ITS2) of the ribosomal RNA gene. Recovered metacercariae from sites, vitreous humor and cranial cavity were previously diagnosed as Diplostomulum cerebralis Chakrabarti, 1968 on the basis of morphological characteristics. A combination of molecular methods in this study depicts that this is a species of genus Tylodelphys Diesing, 1850 which was misinterpreted as Diplostomulum. Hence, in this study, we validated the status of T. cerebralis (=D. cerebralis) after 49 years from its original description. The present work might contribute to expand our knowledge for identification, biodiversity and taxonomy of diplostomids in Indian fishes.