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Biomedical subjects

J Sen

Publications and source records attributed to J Sen.

At least 19 recordsLinked to original sources
PubMed2006

Free phenytoin concentration measurement in brain extracellular fluid: a pilot study.

This article investigates the relationship between brain extracellular fluid free phenytoin concentration and plasma free phenytoin concentration in adults with acute brain injury. Daily cerebral microdialysate free phenytoin concentration was measured in eight adults with acute brain injury and compared with simultaneous measurement of plasma free phenytoin concentration. The group data revealed no significant correlation between microdialysate and plasma free phenytoin concentration (r = 0.34, p = 0.41). However, in two patients, with a sufficient number of samples for intra-individual analysis, there was a significant correlation between microdialysate and plasma free phenytoin concentration (r = 0.92, p < 0.001 and r = 0.88, p < 0.01). In vitro microdialysis relative recovery for phenytoin was 2.1%. In the context of acute brain injury, measurement of free plasma phenytoin concentration may not provide an accurate reflection of regional brain extracellular fluid free phenytoin concentration and may have limitations with respect to achieving reproducible brain extracellular fluid free phenytoin concentrations. This has implications for dosing regimens relying on plasma phenytoin levels.

Adolescent↗
PubMed2005

Extracellular fluid S100B in the injured brain: a future surrogate marker of acute brain injury?

The authors describe the measurement of S100B protein in brain extracellular fluid (ECF) of patients with acute brain injury (traumatic brain injury and subarachnoid haemorrhage) using the technique of microdialysis. To our knowledge, this is the first report of S100B measurement in the human brain. Acute Brain Injury (ABI) is a leading cause of death and disability and the need for a practical and sensitive biochemical marker for monitoring these patients is urgent. The calcium binding astrocyte protein, S100B, may be a candidate for this role. Previous serum studies have shown S100B to be a sensitive predictor of mortality and rise in intracranial pressure in ABI, but it has never before been measured directly within the brain. The ECF reflects the local biochemistry of the brain parenchyma, and the use of intracerebral microdialysis opens up the possibility of studying many novel surrogate markers of injury in the laboratory, in addition to the conventional markers it measures at the bedside (lactate, pyruvate, glucose, and glycerol). In this preliminary report of two cases, the authors demonstrate the quantification of S100B in ECF microdialysate, and investigate whether changes in hourly S100B profile can be related to secondary brain injury. It is shown that extracellular concentrations of S100B change markedly in response to secondary brain injury. Further investigation is required to determine whether extracellular S100B measurement in ABI could assist in patient management.

Adult↗
PubMed2005

Axonal pathology in subarachnoid and intracerebral hemorrhage.

Electrically active axons degenerate in the presence of nitric oxide (NO) in vitro. High CSF NO concentrations have been observed in patients with hemorrhagic brain injury such as subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH). This study investigated the evidence for axonal injury in SAH and ICH and related this to CSF NO levels. In this study, neurofilament phosphoforms (NfH(SMI34), NfH(SMI35), NfH(SMI38), NfH(SMI310)), surrogate markers for axonal injury, and NO metabolites (nitrate, nitrite = NOx) were measured by ELISA in cerebrospinal fluid (CSF) from patients with SAH and ICH and from a group of controls. Injury severity was classified using the Glasgow Coma Scale, and survival was used as the outcome measure. Compared to the control group, a higher proportion of patients with SAH and ICH had elevated NfH(SMI34) levels from day 0 to day 6 (p < 0.001), elevated NfH(SMI35) levels from day 1 to 6 (p < 0.001), and elevated NfH(SMI310) levels at day 0, 1, 4, and 6 (p < 0.001). The NOx levels were higher in the SAH and ICH patients than in the controls (p < 0.05) and distinguished the non-survivors from the survivors (p < 0.05). No direct correlation was found for NOx with any of the NfH phosphoforms. This study provides evidence for primary and secondary axonal injury in patients with SAH and ICH, with non-survivors also having higher NOx levels. CSF NfH phosphoforms might emerge as a putative surrogate marker for monitoring the development for secondary axonal degeneration in neurocritical care and guiding targeted neuroprotective strategies.

Adult↗
PubMed2004

Use of a herbicide or lysine plus threonine for non-antibiotic selection of transgenic chickpea.

A desensitized aspartate kinase (AK) gene has been developed as a non-antibiotic selection marker for use in the production of transgenic chickpea ( Cicer arietinum L.). Transgenic shoots regenerated from embryo explants bombarded with the desensitized AK gene were selected on media containing two amino acids, lysine and threonine (LT). Approximately 15% of the putative transgenic shoots of vars. P-362 and P-1042 survived after 4 weeks of growth on MSB5 medium (MS mineral salts and B5 vitamins) containing 2 microM thidiazuron (TDZ) and 2 mM lysine and 2 m M threonine. These shoots were subsequently grown on MSB5 medium supplemented with 2 micro M TDZ and 5 mM lysine and 5 mM threonine, and nearly 1% continued to grow after 16 weeks of selection. A phosphinothricin (PPT) selection system for Agrobacterium-mediated chickpea transformation was also developed. Three varieties of chickpea, P-362, P-1042 and P-1043, were successfully used for Agrobacterium transformation. Following Agrobacterium infection, 3-8% of the regenerated shoots remained green and continued to grow on MSB5 medium supplemented with 2.5 mg l(-1 )PPT. Increasing the concentrations of PPT to 15 mg l(-1) reduced transgenic shoot production in P-362, P-1042 and P-1043 to 0.7%, 1.2% and 1.1%, respectively. Selected putatively transformed shoots of all three varieties were rooted and grown to maturity. Southern hybridization analysis revealed single as well as multiple integration of genes in selected transgenic lines. The level of AK activity detected in LT-selected plants was higher than that detected in the non-transformed control.

Agrobacterium tumefaciens↗
PubMed2003

A prospective study of the rate of falls before and after cataract surgery.

BACKGROUND: There has been considerable interest in the development of intervention programmes aimed at reducing the risk of falls. The primary objective was to ascertain whether cataract surgery reduced the risk of falls in elderly patients with age related cataract. METHODS: 97 patients scheduled for cataract surgery were enrolled in this prospective clinical study. The patients were assessed for established risk factors for falls preoperatively and postoperatively. Patients were issued with a diary to record any falls and phoned at 2 monthly intervals during the 6 month preoperative and postoperative periods. RESULTS: Of the 84 patients who completed the study, 31 recorded falls during the preoperative period (37%). This group showed a statistically significant reduction in the number of fallers in the postoperative period (n = 6, p<0.001) CONCLUSION: These results suggest that cataract surgery is an effective intervention to reduce the risk of falls in elderly patients with cataract related visual impairment.

Accidental Falls↗
PubMed2003

Clinical profile in gelatinous bone marrow transformation.

OBJECTIVE: To study the clinical spectrum associated with gelatinous bone marrow transformation (GMT). METHODS: All subjects whose bone marrow aspiration showed pink purple material on Leishman stain underwent a detail history, clinical examination and investigation (biochemical/microbiological/radiological). Additionally, in each subject the smear was stained with special stains of Periodic Acid Schiff and Alcian blue. RESULTS: Out of total 1498 marrows, 65 showed evidence of GMT. All of these had anaemia. The associated clinical spectra of diseases noticed were: Infection (31 cases), Nutritional deficiency (5 cases), Haematological disorders (Aplastic/toxic depression) (17 cases), Malignancies (3 cases), and Miscellaneous (9 cases). CONCLUSION: Based on the heterogenecity of associated clinical disorders, GMT indicates severe illness and not a particular disease. GMT may be a result of bioregulatory process (which presently needs further prospective studies) that are activated in different pathologic conditions but resulting in similar lesion in the bone marrow and so till then it may be concluded that GMT is a symptom of bone marrow.

Adolescent↗
PubMed2001

p38 MAP kinase activity modulates alpha beta T cell development.

Reciprocal interactions between bone marrow derived precursor cells and the thymic environment lead to the generation of the complete repertoire of diverse and functional T cells. We have previously shown that p38 MAP kinase is activated in response to intrathymic signals in thymocytes. In this report we provide evidence that p38 MAP kinase activity is essential for pre-TCR-mediated transition of thymocytes from the CD4- CD8- to the CD4+ CD8+ stage of development. In the absence of p38 MAP kinase activity differentiation of alpha beta T cells, but not gamma delta T cells, was blocked.

Animals↗
PubMed2001

Brief communication: Choice of washing method of hair samples for trace element analysis in environmental studies.

Determination of inseparable exogenous and endogenous levels of toxic trace elements such as lead in human scalp hair has been used to understand and assess population exposure to such elements. For any such analysis, washing of the hair samples to remove superficial contamination is the foremost requirement. However, the use of such washing methods prior to elemental analysis removes minute quantities of trace elements from the hair strands. This degree of loss is dependent on the washing method employed. In the present study, the element lead has been determined in human scalp hair after three methods of hair washing. It is apparent that the nonionic detergent-acetone method is best suited for securing valid lead analysis results in human scalp hair.

Acetone↗
PubMed2001

Hydrocortisone replacement dosage influences intraocular pressure in patients with primary and secondary hypocortisolism.

BACKGROUND: It has been suggested that the variation of intraocular pressure (IOP) during the day follows the diurnal variation of serum cortisol. There is also a higher risk of ocular hypertension and glaucoma in patients taking excessive oral steroid treatment. We assessed whether different replacement doses of hydrocortisone (HC) influenced IOP. METHODS: Seventeen patients (six Addison's disease, 11 hypopituitarism; seven males) aged 24-58 years mean 42.7 years and 20 control subjects (nine males) aged 20--59 years mean 38.7 years were studied. On the first visit, the 17 patients had been taking HC replacement doses, 20 mg morning and 10 mg afternoon. Serum cortisol and IOP in both eyes (Goldmann applanation tonometer) were measured at 0900, 1100, 1300, 1500, 1700 hours with HC 20 mg taken after the 0900 h assessment. The dose of HC was then reduced to 10 mg morning and 10 mg afternoon for 1 week and the measurements were repeated in 16 patients, with HC 10 mg taken at 0900 h. RESULTS: In the patients the peak serum cortisol occurred at 1100 h after the 0900 h HC dose. Cortisol levels were significantly higher at 1100, 1300, 1500 and 1700 h after taking 20 mg compared to 10 mg HC. The mean (SEM) IOP (mmHg) was significantly higher after 20 mg HC compared with 10 mg HC at 1300 h: 14.7(0.6) v 13.1(0.6) (P = 0.004) and at 1500 h: 14.4(0.6) v 13.1(0.5) (P = 0.04). The total mean (SEM) daily IOP score was significantly higher after 20 mg HC compared with 10 mg HC: 14.5(0.3) v 13.5(0.3) (P = 0.0002). The total mean (SEM) daily IOP score after the 20 mg HC dose compared with the control subjects was: 14.5(0.3) v 13.7(0.3) (P = 0.08). CONCLUSION: Intraocular pressures during the day are influenced by the morning hydrocortisone replacement dosage with significantly higher intraocular pressure levels in the early afternoon following 20 mg compared with 10 mg. A morning hydrocortisone dose of 10 mg leads to a more physiological intraocular pressure profile during the day. These data support the view that a daily replacement dose of 30 mg hydrocortisone may be excessive.

Addison Disease↗
PubMed2001

Signal transduction in thymus development.

Reciprocal interaction between bone marrow derived lymphoid precursor cells and the thymic environment leads, through a series of developmental events, to the generation of a diverse repertoire of functional T-cells. During thymopoiesis fetal liver or bone marrow derived precursors enter the thymus and develop into mature T-cells in response to cues derived from the environment. The thymic micro-environment provides signals to the lymphoid cells as a result of cell-cell interactions, locally produced cytokines, chemokines and hormones. Developing thymocytes, in turn, influence the thymic stroma to form a supportive micro-environment. Stage-specific signals provide an exquisite balance between cellular proliferation, differentiation, cell survival and death. The result of this intricate signaling concert is the production of the requisite numbers of well educated self-restricted T-cells. Mature T-cells are exported to the peripheral lymphoid organs, where, upon encountering antigen, naive T-cells further mature into effector cells that provide cytolytic or T helper functions. While there are extra-thymic locations for T-cell development, majority of T-cells in peripheral lymphoid organs are thymus derived. In mice and humans, T-cells develop throughout life although the efficacy declines significantly with age. It is not clear if this is a direct consequence of deterioration of the thymic environment by involution, a paucity of bone marrow derived precursors, or both. However, new data clearly shows that the involuted adult thymus retains the ability to generate new T-cells. Recent advances have revealed many components of an exquisitely balanced signaling cascades that regulate cell fate, cellular proliferation and cell death in the thymus. This article describes fundamental features of developing thymocytes and the thymic micro-environment as they relate to the signaling pathways.

Animals↗
PubMed2000

Multiple neurilemmomas of the penis.

A 10-year-old male with multiple small swellings over the shaft of the penis for 2 years was found to have multiple neurilemmomas on histopathologic examination. The case is reported in view of the extreme rarity of the entity.

Biopsy↗
PubMed2000

Caudal duplication--a case report.

Caudal duplication is a rare entity due to incomplete separation of mono-ovular twins. It is usually associated with various congenital malformations involving mainly the genitourinary and gastrointestinal tracts. We report such a case operated upon successfully in which there was no other associated anomaly.

Anal Canal↗
PubMed2000

The homeobox gene mirror links EGF signalling to embryonic dorso-ventral axis formation through notch activation.

Recent studies in vertebrates and Drosophila melanogaster have revealed that Fringe-mediated activation of the Notch pathway has a role in patterning cell layers during organogenesis. In these processes, a homeobox-containing transcription factor is responsible for spatially regulating fringe (fng) expression and thus directing activation of the Notch pathway along the fng expression border. Here we show that this may be a general mechanism for patterning epithelial cell layers. At three stages in Drosophila oogenesis, mirror (mirr) and fng have complementary expression patterns in the follicle-cell epithelial layer, and at all three stages loss of mirr enlarges, and ectopic expression of mirr restricts, fng expression, with consequences for follicle-cell patterning. These morphological changes are similar to those caused by Notch mutations. Ectopic expression of mirr in the posterior follicle cells induces a stripe of rhomboid (rho) expression and represses pipe (pip), a gene with a role in the establishment of the dorsal-ventral axis, at a distance. Ectopic Notch activation has a similar long-range effect on pip. Our results suggest that Mirror and Notch induce secretion of diffusible morphogens and we have identified TGF-beta (encoded by dpp) as such a molecule in germarium. We also found that mirr expression in dorsal follicle cells is induced by the EGF-receptor (EGFR) pathway and that mirr then represses pip expression in all but the ventral follicle cells, connecting EGFR activation in the dorsal follicle cells to repression of pip in the dorsal and lateral follicle cells. Our results suggest that the differentiation of ventral follicle cells is not a direct consequence of germline signalling, but depends on long-range signals from dorsal follicle cells, and provide a link between early and late events in Drosophila embryonic dorsal-ventral axis formation.

Animals↗
PubMed2000

Subcutaneous cysticercosis involving the eyelid: sonographic diagnosis.

A 25-year-old man and a 14-year-old boy presented with neurocutaneous cysticercosis involving the eyelid. Both patients had hundreds of scattered subcutaneous cysticerci. They were arranged in clusters over the sternocleidomastoid muscle in the neck. Such clustering of cysticerci is highly suggestive of central nervous system (CNS) involvement, as both the sternocleidomastoid muscle and the CNS are supplied by the carotid artery and cysticerci travel via the hematogenous route. We used ultrasonography to diagnose subcutaneous cysticercosis, which showed characteristic low reflective cysts and high reflective scolices inside. Although subcutaneous cysticerci are inconsequential, their verification is important in the diagnosis of more severe CNS involvement. They may be confused with other painless swellings such as lymphadenopathies, neurofibromas, and epidermoid cysts.

Adolescent↗