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Biomedical subjects

Vivek Jain

Publications and source records attributed to Vivek Jain.

At least 19 recordsLinked to original sources
PubMed2024

Clinical and genetic delineation of autosomal recessive and dominant ACTL6B-related developmental brain disorders.

PURPOSE: This study aims to comprehensively delineate the phenotypic spectrum of ACTL6B-related disorders, previously associated with both autosomal recessive and autosomal dominant neurodevelopmental disorders. Molecularly, the role of the nucleolar protein ACTL6B in contributing to the disease has remained unclear. METHODS: We identified 105 affected individuals, including 39 previously reported cases, and systematically analyzed detailed clinical and genetic data for all individuals. Additionally, we conducted knockdown experiments in neuronal cells to investigate the role of ACTL6B in ribosome biogenesis. RESULTS: Biallelic variants in ACTL6B are associated with severe-to-profound global developmental delay/intellectual disability, infantile intractable seizures, absent speech, autistic features, dystonia, and increased lethality. De novo monoallelic variants result in moderate-to-severe global developmental delay/intellectual disability, absent speech, and autistic features, whereas seizures and dystonia were less frequently observed. Dysmorphic facial features and brain abnormalities, including hypoplastic corpus callosum, and parenchymal volume loss/atrophy, are common findings in both groups. We reveal that in the nucleolus, ACTL6B plays a crucial role in ribosome biogenesis, particularly in pre-rRNA processing. CONCLUSION: This study provides a comprehensive characterization of the clinical spectrum of both autosomal recessive and dominant forms of ACTL6B-associated disorders. It offers a comparative analysis of their respective phenotypes provides a plausible molecular explanation and suggests their inclusion within the expanding category of "ribosomopathies."

Humans↗
PubMed2006

Oxidative stress and oxidant signaling in obstructive sleep apnea and associated cardiovascular diseases.

Obstructive sleep apnea (OSA) has emerged as a major public health problem and increasing evidence indicates that untreated OSA can lead to the development of various cardiovascular disorders. One important mechanism by which OSA may promote cardiovascular diseases is intermittent hypoxia, in which patients are subjected to repeated episodes of brief oxygen desaturation in the blood, followed by reoxygenation. Such cycles of hypoxia/reoxygenation may result in the generation of reactive oxygen species. Some studies have demonstrated the presence of oxidative stress in OSA patients as well as in animals subjected to intermittent hypoxia. Further, modulations of nitric oxide and biothiol status might also play important roles in the pathogenesis of OSA-associated diseases. Reactive oxygen species and redox events are also involved in the regulation of signal transduction for oxygen-sensing mechanisms. This review summarizes currently available information on the evidence for and against the occurrence of oxidative stress in OSA and the role of reactive oxygen species in cardiovascular changes associated with OSA.

Animals↗
PubMed2005

Serotype diversity and reassortment between human and animal rotavirus strains: implications for rotavirus vaccine programs.

The development of rotavirus vaccines that are based on heterotypic or serotype-specific immunity has prompted many countries to establish programs to assess the disease burden associated with rotavirus infection and the distribution of rotavirus strains. Strain surveillance helps to determine whether the most prevalent local strains are likely to be covered by the serotype antigens found in current vaccines. After introduction of a vaccine, this surveillance could detect which strains might not be covered by the vaccine. Almost 2 decades ago, studies demonstrated that 4 globally common rotavirus serotypes (G1-G4) represent >90% of the rotavirus strains in circulation. Subsequently, these 4 serotypes were used in the development of reassortant vaccines predicated on serotype-specific immunity. More recently, the application of reverse-transcription polymerase chain reaction genotyping, nucleotide sequencing, and antigenic characterization methods has confirmed the importance of the 4 globally common types, but a much greater strain diversity has also been identified (we now recognize strains with at least 42 P-G combinations). These studies also identified globally (G9) or regionally (G5, G8, and P2A[6]) common serotype antigens not covered by the reassortant vaccines that have undergone efficacy trials. The enormous diversity and capacity of human rotaviruses for change suggest that rotavirus vaccines must provide good heterotypic protection to be optimally effective.

Animals↗
PubMed2005

Intra-arterial thrombolysis of embolic middle cerebral artery using collateral pathways.

BACKGROUND AND PURPOSE: Cervical internal carotid artery (ICA) occlusion associated with middle cerebral artery (MCA) embolic occlusion requires prompt revascularization to prevent devastating stroke. With the advent of endovascular techniques for chemical and mechanical thrombolysis, the clinical outcome of patients with major arterial occlusions will improve. Finding the most expedient pathway to the site of end organ occlusion for thrombolysis is important. METHODS: We present two cases of acute stroke secondary to thrombotic occlusion of the cervical ICA associated with MCA embolic occlusion treated with intra-arterial thrombolysis via catheter navigation through the posterior communicating artery to the site of MCA arterial occlusion. No attempt was made to transverse the occluded ICA. RESULTS: Near complete restoration of flow was achieved in one patient and minimal vessel reopening was observed in the other patient. Both patients had good outcomes. CONCLUSION: Intra-arterial thrombolysis via Circle of Willis collaterals such as the posterior communicating artery for the treatment of acute thrombotic occlusion of the cervical internal carotid artery associated with embolic occlusion of the middle cerebral artery is a therapeutic option. This treatment option avoids the potential complications of navigating through an occluded proximal internal carotid artery and may expedite reopening of the MCA.

Aged↗
PubMed2004

Lack of improvement in patients with acute stroke after treatment with thrombolytic therapy: predictors and association with outcome.

CONTEXT: The focus of thrombolytic therapy in acute stroke has been on favorable outcome at 3 months. Few studies have analyzed outcome at 24 hours. An early and reliable prediction of poor outcome has implications for clinical management and discharge planning. OBJECTIVE: To evaluate predictors of lack of improvement at 24 hours after receiving alteplase and their relationship with poor outcome at 3 months. DESIGN, SETTING, AND PARTICIPANTS: Prospective cohort of consecutive patients with acute stroke who received alteplase and were admitted to a university hospital from January 1999 to March 2003. Participants were recruited from 2 academic centers in a major city in Ontario and 33 affiliated hospitals from 7 counties. MAIN OUTCOME MEASURES: Lack of improvement defined as a difference between the National Institutes of Health Stroke Scale score at baseline and at 24 hours of 3 points or less. Poor outcome at 3 months defined by a modified Rankin Scale score of 3 to 5 or death. RESULTS: Among 216 patients with acute stroke who were treated with alteplase, 111 (51.4%) had a lack of improvement at 24 hours. After adjusting for age, sex, and stroke severity, baseline glucose level on admission (odds ratio [OR] 2.89; 95% confidence interval [CI], 1.40-5.99 for a glucose level >144 mg/dL [>8 mmol/L]), cortical involvement (OR, 2.66; 95% CI, 1.36-5.20), and time to treatment (OR, 1.01; 95% CI, 1.0-1.02 for each 1 minute increase in time to treatment) were independent predictors of lack of improvement. At 3 months, 43 patients (20.2%) had died; of the 170 survivors, 75 patients (44%) had poor outcomes. After adjusting for age, sex, and stroke severity, lack of improvement at 24 hours was an independent predictor of poor outcome (OR, 12.9; 95%CI, 5.7-29.6) and death (OR, 7.5; 95% CI, 2.9-19.6). Patients with a lack of improvement had longer lengths of hospitalization (14.5 vs 9.6 days; P = .02). CONCLUSIONS: Among patients with acute stroke treated with thrombolytic therapy, lack of improvement at 24 hours is associated with poor outcome and death at 3 months. Elevated glucose level, time to thrombolytic therapy, and cortical involvement were predictors of lack of improvement.

Aged↗
PubMed2004

Griscelli syndrome.

An eight month old male infant presented with recurrent infections and partial albinism. Initially a possibility of Chediak Higashi syndrome (CHS) was considered, but a negative investigative work up prompted us to look for an alternate diagnosis. A literature search revealed that Griscelli syndrome (GS) has overlapping symptoms and signs. The findings in skin and hair biopsies in Griscelli syndrome are distinctive.

Chediak-Higashi Syndrome↗
PubMed2004

Assessment of the epidemic potential of a new strain of rotavirus associated with the novel G9 serotype which caused an outbreak in the United States for the first time in the 1995-1996 season.

Rotavirus causes severe morbidity in developed countries and frequent deaths (> or = 500,000 per year) in less-developed countries. Historically, four serotypes--G1, G2, G3, and G4-have predominated; they are distinguished by one of two surface neutralization antigens (VP7). However, in 1983 and 1984 we described a new rotavirus serotype, designated G9, in five children hospitalized for diarrhea in Philadelphia, Pa. G9 rotavirus was not identified again in the Western Hemisphere until it caused ca. 50% of the rotavirus disease detected in Philadelphia in the 1995-1996 season. This outbreak allowed us to question whether a rotavirus strain completely new to a well-studied community would target either very young infants or older children, cause especially severe disease, or completely displace previously extant serotypes. We observed a significant excess of G9 infections in younger infants (especially in those < 6 months old) that might be attributed to the lack of G9-specific antibodies in mothers. Of further note, six of the seven oldest patients with rotavirus diarrhea were infected with the G9 strains (not significant). However, the age distribution of children with rotavirus did not differ over a 5-year study period regardless of the infecting serotype. Patients with diarrhea associated with G9 strains did not have disease more severe than that caused by the G1, G2, or G3 serotype. G9 strains did not displace the other serotypes but were virtually completely replaced by G1 or G2 serotypes in the three subsequent rotavirus seasons. We conclude that the abrupt appearance of this novel rotavirus serotype did not present a special threat to public health in the community.

Age Distribution↗
PubMed2004

Corticosteroids versus albendazole for treatment of single small enhancing computed tomographic lesions in children with neurocysticercosis.

Single small enhancing computed tomographic (CT) lesions representing cysticercus granuloma are a common cause of focal seizures in children. Controversy exists regarding the efficacy of various modalities of treatment. We conducted a randomized prospective trial to evaluate the efficacy of corticosteroids, albendazole, and corticosteroids with albendazole in children with focal seizures and single small enhancing CT lesions. The study population consisted of 133 children with focal seizures of recent onset (< 3 months) and single small enhancing CT lesions who presented to the Neurocysticercosis Clinic of Pediatric Neurology Services at the Advanced Pediatrics Centre, Postgraduate Institute of Medical Education and Research, an urban teaching and tertiary care hospital in Chandigarh, North India. All children were randomly assigned to receive corticosteroids (group S), albendazole (group A), or both corticosteroids and albendazole (group SA) for 28 days. CT was done at 3 and 6 months after enrollment in the study. Of the 133 patients enrolled, 23 were lost to follow-up. Of the remaining 110 patients, 38 patients were in group S, 37 in group A, and 35 in group SA. All children were followed up for at least 18 months. Disappearance of the lesion on CT scan was noted in 52.6% of patients in group S, 59.5% in group A, and 62.9% in Group SA (P > .1) at the 3-month follow-up. After the 6-month follow-up, disappearance of the lesion was noted in 76.3% in group S, 75.7% in group A, and 74.2% in group SA (P > .1). Twenty-three patients had seizure recurrence while on antiepilepsy drugs: 36.8% of patients in group S, 13.5% in group A, and 11.4% in group SA (P < .05). Seizure recurrence after antiepilepsy drug withdrawal was seen in seven children (three in group S and two each in groups A and SA). In conclusion, there was no significant difference in resolution of CT lesions in the three therapy groups at 3 and 6 months of follow-up. Children in the corticosteroid group had significantly more seizure recurrences while on antiepilepsy drugs.

Adolescent↗
PubMed2003

Influence of wettability and saturation on liquid-liquid interfacial area in porous media.

The knowledge of the area of interfaces between phases is important to understand and quantify many flow and transport processes in porous media. In this work, we apply the interfacial tracer technique to study the dependence of fluid-fluid interfacial area on saturation and wettability. The interfacial area between the wetting and the nonwetting phases (brine and decane) in unconsolidated porous media (glass beads) was measured using an anionic surfactant (3-phenyl decyl benzene sulfonate) as an interfacial tracer. The beads are water-wet; treating them with organosilane rendered them oil-wet. The measurements were done at a series of steady-state fractional flows, providing data at intermediate as well as residual saturations. Flow rates were kept low so that capillary forces controlled the fluid configurations. We observe significant differences in interfacial areas as a function of wetting-phase saturation as the wettability is changed from water-wet to oil-wet. During primary drainage, measured interfacial area increases monotonically with decreasing water saturation in a water-wet medium. In contrast, the interfacial area measured in the oil-wet porous medium increases with decreasing decane saturation, reaches a maximum, and decreases as the residual decane saturation is achieved. The oil-wet experiment is qualitatively consistent with theoretical results that predict the existence of a maximum in fluid-fluid interfacial area during drainage. The water-wet experiment is consistent with theoretical predictions that include the area of grains in pores that have been drained. We conclude that, in the water-wet experiments, the tracer adsorbs at the interface between the nonwetting phase and the wetting films on grains. In the oil-wet experiments, either the oil films are not sustained at high water saturation or the tracer does not adsorb at them, possibly prevented by steric hindrance. Interpretation of interfacial tracer experiments therefore requires care: for some mass transport processes, the thin films of wetting phase on grains will not behave the same as macroscopic volumes of wetting phase.

Chemical Phenomena↗
PubMed2003

Pediatric surgical emergencies in the setting of a natural disaster: Experiences from the 2001 earthquake in Gujarat, India.

BACKGROUND/PURPOSE: On January 26, 2001, a 7.9 Richter earthquake struck the Indian state of Gujarat. Over the next 6 days, the International Red Cross set up a mobile hospital in the city of Bhuj, near the epicenter. The authors describe all surgeries on children treated there during the first 4 weeks of operation. The evolution of presenting injuries is noted, the types of surgery required are classified and an effective disaster relief team composition and strategy are proposed. METHODS: Total casualties were estimated at 30,000, with 250,000 people injured. Of 1,142 inpatients treated at Nor-Finn hospital during the first 4 weeks, approximately 300 (25%) were </=17 years old. Of these, the authors report on the 62 who underwent surgery. Demographic data collected includes (where possible) age, date of presentation, injury, and surgery performed. Injuries are classified as orthopedic, soft tissue, burns, or miscellaneous. Injuries are grouped in 4 weekly time periods beginning February 1 when the hospital opened. RESULTS: Children's ages were evenly distributed. Children required surgery less often than adults. Of children needing surgery, 42% needed orthopedic attention, 42% had soft tissue trauma, 10% had burns, and 6% had miscellaneous injuries. During the hospital's first week, operations were predominantly orthopedic. During the second week, orthopedic and soft tissue injuries occurred at similar frequency. In weeks 3 and 4, soft tissue and burn surgeries were prevalent. CONCLUSIONS: More than 25% of patients requiring hospitalization were children, of whom greater than 20% needed surgery. The operations fell into 4 categories: orthopedic, soft tissue injuries, burns, and miscellaneous. There was an immediate need for orthopedic and general surgery skills followed by a delayed need for plastic surgery skills.

Adolescent↗
PubMed2003

Toe-to-hand transplantation.

In the mutilated hand microsurgical toe-to-hand transplantation provides thumb and finger reconstruction that is superior to conventional techniques in appearance and function. Hand reconstruction using toe transplantation should be individually planned and carefully executed to obtain optimal results and minimal disability in the donor foot.

Amputation, Traumatic↗
PubMed2003

Bell's palsy in children.

Bell's palsy is a self-limiting idiopathic rapid onset facial palsy that is non-life-threatening and has a generally favorable prognosis. Facial paralysis can be caused by numerous conditions, all of which should be excluded before a diagnosis of Bell's palsy is reached. The etiopathogenesis of Bell's palsy is uncertain; acute immune demyelination triggered by a viral infection may be responsible. Controversy exists regarding treatment options. This article reviews the differential diagnosis and diagnostic and therapeutic options and discusses the controversies related to the various treatment modalities (steroids, acyclovir, and surgery). A simple practical approach to diagnosing and treating children with Bell's palsy is suggested.

Bell Palsy↗
PubMed2003

Angiopoietins have distinct modular domains essential for receptor binding, dimerization and superclustering.

Angiopoietins are a recently discovered family of angiogenic factors that interact with the endothelial receptor tyrosine kinase Tie2, either as agonists (angiopoietin-1) or as context-dependent agonists/antagonists (angiopoietin-2). Here we show that angiopoietin-1 has a modular structure unlike any previously characterized growth factor. This modular structure consists of a receptor-binding domain, a dimerization motif and a superclustering motif that forms variable-sized multimers. Genetic engineering of precise multimers of the receptor-binding domain of angiopoietin-1, using surrogate multimerization motifs, reveals that tetramers are the minimal size required for activating endothelial Tie2 receptors. In contrast, engineered dimers can antagonize endothelial Tie2 receptors. Surprisingly, angiopoietin-2 has a modular structure and multimerization state similar to that of angiopoietin-1, and its antagonist activity seems to be a subtle property encoded in its receptor-binding domain.

Amino Acid Motifs↗
PubMed2003

Pediatric emergencies at a tertiary care hospital in India.

The aim of the present study was to study the epidemiological and clinical profile of patients attending an exclusive pediatric Emergency Department (ED). Data was retrieved from records of the patients seen over a 6-year period from 1995 to 2000. Descriptive analysis was done to define demographic and clinical details, and monthly admission rates and diagnoses. A total of 43800 patients were seen during the study period. Of these 42.1 per cent were admitted after initial evaluation. The ratio of boys to girls was 3:1; 47 per cent were infants under 1 year of age. The common reasons for attending the emergency department were gastrointestinal and respiratory illnesses (23 per cent each), neurological emergencies (16 per cent), and neonatal problems (15.6 per cent). Poisonings were seen in 0.6 per cent of patients. Eight illnesses, i.e. acute diarrhea, upper respiratory infection, pneumonia, acute asthma, seizures, meningitis, and neonatal sepsis and jaundice, comprised nearly half of all the emergency visits. Acute diarrhoeal diseases, pneumonia, asthma, and encephalitis showed a distinct seasonal trend. Our data implies that planning of staff training and triage and efficient resource utilization in the pediatric ED in a developing country such as ours should take into consideration the preponderance of infants, seasonal trends, and the most common emergencies (acute diarrhea, pneumonia, acute asthma, seizures and neonatal infection) as priorities.

Child↗
PubMed2002

Conductivity reduction due to emulsification during surfactant enhanced-aquifer remediation. 1. Emulsion transport.

Surfactant-enhanced aquifer remediation (SEAR) is a promising technology for the remediation of subsurface zones contaminated with organic liquids. To ensure the success of SEAR, the potential reduction in hydraulic conductivity must be evaluated. The objective of this study was to examine the process of conductivity reduction due to the transport of an emulsion, generated by mixing tetrachloroethylene with 4% solutions of two nonionic surfactants, in packed beds of sand-sized silica particles. The injection of the emulsion resulted in a 75-85% reduction in conductivity, depending on the properties of the surfactant and the porous medium. The greater viscosity of the emulsion relative to that of water accounted for about 25% of the reduction. The remainder was attributed to the clogging of the porous medium by the emulsion. The relative sizes of the emulsion droplets and the packed bed's pores, coupled with measurements of zeta potential of the emulsion droplets and silica particles, suggested that multilayer deposition was the principal mechanism of clogging. This hypothesis was corroborated by direct observation of the emulsion transport process in a micromodel. To simulate the reduction in hydraulic conductivity in these systems accurately, it was necessary to modify the emulsion transport model by Soo and Radke to include the phenomena of viscosity variation and multilayering.

Algorithms↗
PubMed2002

Conductivity reduction due to emulsification during surfactant enhanced-aquifer remediation. 2. Formation of emulsion in situ.

Permeability reduction due to surfactant emulsification can impact the effectiveness of surfactant-enhanced aquifer remediation (SEAR). The objective of this study was to examine the process of in situ emulsification in systems composed of tetrachloroethylene (PCE) and solutions of two nonionic surfactants selected for their ability to enhance solubility. The injection of the surfactant solutions into columns packed with sand-sized silica particles containing residual saturations of PCE resulted in the formation of an emulsion with an average droplet diameter of 0.1-0.2 microm, about an order of magnitude smaller than that of the ex situ formed emulsion. The measurements of hydraulic conductivity showed an initial decrease, followed by a gradual increase, with a final steady-state reduction of about 35% after the injection of 7-8 pore volumes of surfactant solution, of which about 8% could be attributed to the deposition of the emulsion. To describe the observed trends, the modified emulsion transport model from Part 1 was modified to include the processes of the formation of the emulsion and the reduction of the PCE residual. The good comparison between the simulations and the experimental data suggests that the model correctly reflects the multiple processes controlling the hydraulic conductivity of the packed columns during surfactant solution injection.

Algorithms↗
PubMed2002

Epileptic monocular nystagmus.

The authors describe a case of epileptic monocular nystagmus in a cognitively intact adult with normal vision. Focal seizures originated in the occipital lobe contralateral to the involved eye, and an associated structural lesion was thought to represent a forme fruste of Sturge-Weber syndrome. It is hypothesized that the seizure discharge either activated a cortical saccade region and caused simultaneous supranuclear inhibition of ipsilateral eye movement or triggered monocular eye movement commands.

Adult↗