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R Sarkar

Publications and source records attributed to R Sarkar.

At least 37 records · Page 2Linked to original sources
PubMed2001

Reproductive phase depedent circadian variation in the pineal biochemical constituents of Indian palm squirrel, Funambulus pennanti.

In mammals, pineal gland is intimately concerned with the co-ordination of rhythm physiology. Biochemical characteristics of pineal gland in man and other mammals may provide strong, yet sometimes elusive support for the belief in functional individuality and probable importance of this tiny gland. In seasonal breeding animals, pineal gland function is very much dependent on the reproductive status. Therefore, the aim of this experiment is to note the circadian rhythmicity of different biochemical constituents of pineal gland during active and inactive phases of reproductive cycle of a seasonally breeding rodent, F. pennanti. In the present study, pineal biochemical constituents i.e. protein and cholesterol showed higher values during daytime (1400 h). The plasma melatonin level presented two peaks during active (April; at 1800 h and 0200 h) and inactive (December; at 1400 h and 0200 h) phases of reproductive cycle. The pineal protein, cholesterol and plasma melatonin values in term of basal and peak levels were higher during the reproductive inactive/pineal active phase. Therefore, pineal--also known to have antigonadotropic properties and cholesterol which appears conjugated with pineal serotonin, presented circadian rhythmicity along with the plasma level of melatonin. This rhythmicity noted in present study was dependent on the reproductive and pineal activity status, and might be regulated by the sex steroid receptor present on the pineal gland.

Animals↗
PubMed2001

Detection of clinically silent infarcts after carotid endarterectomy by use of diffusion-weighted imaging.

BACKGROUND AND PURPOSE: Intraprocedural transcranial Doppler sonography has identified multiple microembolic events during and immediately after carotid endarterectomy (CEA) or angioplasty, yet the rate of clinically evident stroke is small. To determine the significance of the transcranial Doppler sonography findings, we examined patients by use of diffusion-weighted imaging and fluid-attenuated inversion recovery MR imaging before and immediately after CEA for evidence of clinically silent ischemic events. METHODS: Twenty-five patients with atherosclerotic disease of the carotid arteries underwent diffusion-weighted imaging and fluid-attenuated inversion recovery MR imaging performed, on average, 3 days before and 12 hours after CEA. Diffusion-weighted images were acquired in three orthogonal directions at b = 900. Pre- and postoperative neurologic examinations were performed by the same physician. RESULTS: After endarterectomy, 4.0% of the patients (one of 25 patients) showed a single, cortical focus of restricted diffusion and new fluid-attenuated inversion recovery hyperintensity, measuring <1 cm in diameter, ipsilateral to the CEA. The postoperative neurologic examination showed no change in status from the preoperative baseline state. This patient had an intraoperative course complicated by the development of a large luminal thrombus, necessitating thrombectomy. CONCLUSION: The use of diffusion-weighted imaging may serve to improve conspicuity of clinically silent infarcts after CEA. An important next step is to determine the risk factors that predispose to detectable parenchymal ischemic events.

Aged↗
PubMed2001

Alginate immobilization of Spirulina platensis for wastewater treatment.

Immobilization of cyanobacterium Spirulina platensis in sodium alginate (1.5 %) gave the best quality of bead and 15-16 beads were formed per mL of aqueous solution of alginate. The immobilized cells were used in a batch process for treatment of diluted sewage. After 8 days, 95 % of BOD5, 77 % of COD, 90 % of ammonia, and 94 % of TSS were removed.

Alginates↗
PubMed2000

Correction of the coagulation defect in hemophilia A mice through factor VIII expression in skin.

To test the hypothesis that factor VIII expressed in the epidermis can correct hemophilia A, we generated transgenic mice in a factor VIII-deficient background that express human factor VIII under control of the involucrin promoter. Mice from 5 transgenic lines had both phenotypic correction and plasma factor VIII activity. In addition to the skin, however, some factor VIII expression was detected in other tissues that have stratified squamous epithelia. To determine whether an exclusively cutaneous source of factor VIII could correct factor VIII deficiency, we grafted skin explants from transgenic mice onto mice that are double knockouts for the factor VIII and RAG-1 genes. Two graft recipients had plasma factor VIII activity of 4% to 20% of normal and improved whole blood clotting compared with factor VIII-deficient mice. Thus, expression of factor VIII from the epidermis can correct hemophilia A mice, thereby supporting the feasibility of cutaneous gene therapy for systemic disease. (Blood. 2000;95:2799-2805)

Animals↗
PubMed2000

Partial correction of murine hemophilia A with neo-antigenic murine factor VIII.

We have previously reported a factor VIII knockout (FVIII KO) mouse model for hemophilia A. Here we demonstrate the presence of nonfunctional heavy chain factor VIII protein in the mouse, making it an excellent model for cross-reacting material (CRM)-positive hemophilia A patients, who express normal levels of a dysfunctional FVIII protein. We attempted to correct these mice phenotypically by transduction of wild-type mouse factor VIII cDNA delivered in an E1/E3-deleted adenoviral vector by tail vein injection. All treated mice displayed initial high-level FVIII expression that diminished after 1 month. Ten of 12 mice administered between 6 x 10(9) and 1 x 10(11) particles/mouse along with anti-CD4 antibody showed long-term FVIII activity (0.03-0.05 IU/ml, equivalent to 3-5% of normal FVIII) that corrected the phenotype. Wild-type murine FVIII was a neo-antigen to the KO mice, generating both cytotoxic and humoral immune responses. Immune suppression with anti-CD4 antibody abrogated these immune responses. These data demonstrate that despite the presence of endogenous FVIII protein the immune system still recognizes a species-specific transgene protein as a neo-antigen, eliciting a cytotoxic T cell response. This phenomenon may exist in the treatment of other genetic disorders by gene therapy.

Adenoviridae↗
PubMed2000

Dexamethasone inhibits the phosphorylation of retinoblastoma protein in the suppression of human vascular smooth muscle cell proliferation.

We have previously demonstrated that dexamethasone (DEX) suppresses neointimal hyperplasia and proliferation of rat aortic smooth muscle cells (SMC) by inducing a late G1 phase cell cycle arrest. Phosphorylation of retinoblastoma protein (Rb) regulates cell proliferation by controlling progression from G1 to S phase of the cell cycle. We hypothesized that DEX inhibits human vascular SMC proliferation and causes cell cycle arrest through inhibition of Rb phosphorylation. Human aortic SMC were cultured and treated with incremental doses of DEX. Cell counts and [(3)H]thymidine uptake were determined after 72 h. To examine the effects of DEX on the cell cycle, cells were synchronized by serum deprivation, restimulated to enter G1 phase, and treated with 10(-5) M DEX, and protein was extracted at sequential time points. Flow cytometry was performed to track cell cycle progression. Western blots were performed to examine Rb phosphorylation. DEX inhibited smooth muscle cell proliferation and DNA synthesis in a concentration-dependent fashion. Flow cytometry indicated that DEX induces a G1 phase cell cycle arrest. DEX inhibited the phosphorylation of Rb protein compared to control. DEX inhibits the proliferation of human vascular SMC by inducing G1 phase cell cycle arrest. DEX inhibited the phosphorylation of Rb, a key step in the progression of the cell from G1 to S phase. Elucidation of the mechanism of DEX may be helpful in treatment strategies for preventing neointimal hyperplasia as well as other disorders of cell proliferation.

Aorta↗
PubMed2000

Incidence of femoral and popliteal artery aneurysms in patients with abdominal aortic aneurysms.

OBJECTIVE: The purpose of this study was to determine the incidence of femoral and popliteal aneurysms in men and women who have abdominal aortic aneurysms (AAAs) and to assess potential etiologic differences in patients with and without these lower extremity aneurysms. METHODS: We studied 313 consecutive patients with AAAs encountered from 1995 to 1998 who underwent prospective ultrasound scanning to detect the presence or absence of femoral and popliteal aneurysms. Patients with and without these extremity aneurysms were compared for differences in potential etiologic risk factors with each other and with a statewide population of patients with AAAs. RESULTS: A total of 51 femoral and popliteal aneurysms were encountered, all occurring in male patients. Among the 251 men with AAAs, the incidence of femoral or popliteal aneurysms was 14%, compared with 0% among the 62 women with AAAs (P <.01). A family history of aneurysmal disease was present in only one (3%) of the 36 men with these extremity arterial aneurysms, a significant finding (P <.01) when compared with the family history that was positive for aneurysmal disease in 14 women (23%). Peripheral arterial occlusive disease affected 14 (39%) of the 36 men with peripheral arterial aneurysms versus 20 (9%) of the 215 men without these aneurysms (P <.01). Most other etiologic variables studied proved not to be different among the various groups of patients examined. CONCLUSION: The incidence of femoral and popliteal aneurysms in persons with AAAs appears higher than that noted previously. Femoral and popliteal aneurysmal disease preferentially affects men; however, the basis for this sex difference is unknown. Few common etiologic factors differed between men with and without these extremity aneurysms. Most femoral and popliteal artery aneurysms in this study were undetectable on physical examination, suggesting that ultrasound scanning is appropriate in the recognition of peripheral aneurysms among men with AAAs.

Aged↗
PubMed2000

Three unusual siblings with Harlequin icthyosis in an Indian family.

Harlequin fetuses occurring as three siblings in an Indian family are described here. All three were preterm, low birth weight, and did not survive. There was no history of consanguinous marriage in the parents or in the family. Thus autosomal recessive inheritance appears to be a remote possibility, although not impossible or, as recently described, these recurrent harlequin fetuses could be the result of new dominant mutations with parental mosaicism.

Female↗
PubMed2000

Effects of an organophosphate pesticide, quinalphos, on the hypothalamo-pituitary-gonadal axis in adult male rats.

The effects of chronic sub-lethal doses (7-14 mg kg-1 a day for 15 days) of quinalphos were evaluated in adult male rats for changes in testicular morphology, circulatory concentrations of hormones (LH, FSH, prolactin and testosterone), activities of acetylcholinesterase (AChE) and angiotensin converting enzyme (ACE) as well as metabolism of biogenic amines (dopamine, noradrenaline and 5-hydroxytryptamine (5-HT)) in the hypothalamus and pituitary. Hormones were assayed by radioimmunoassay or chemiluminescent immunoassay (testosterone). The enzymes were estimated after spectrophotometry and the biogenic amines by HPLC-electrochemistry. Sub-lethal chronic administration of quinalphos resulted in: decreased testicular mass and AChE activity in central as well as peripheral organs; increased serum LH, FSH, prolactin and testosterone concentrations; decreased pituitary or increased testicular ACE activity; severe disruption of spermatogenesis with increasing doses of pesticide; and no significant effects on dopamine, noradrenaline or 5-HT concentrations in the hypothalamus or pituitary. Administration of oestradiol (50 micrograms per rat a day) during pesticide treatment resulted in: a significant decrease in the mass of the testis and accessory sex organs; decreases in serum LH, FSH, testosterone concentrations; an increase in prolactin concentration; and a decrease in dopamine or an increase in noradrenaline and 5-HT in the hypothalamus or pituitary. Oestradiol had a marked effect: in pesticide-treated animals, the pesticide effects were significantly reversed. This indicates that in pesticide toxicity, the hypothalamo-pituitary-gonadal axis is operational. Since many of the observed pesticide effects could be inhibited by oestradiol, it is suggested that the pesticide acts directly on the gonadotrophins. In conclusion, quinalphos decreases fertility in adult male rats by affecting the pituitary gonadotrophins.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

Short-term correction of factor VIII deficiency in a murine model of hemophilia A after delivery of adenovirus murine factor VIII in utero.

Development of in utero gene transfer approaches may provide therapies for genetic disorders with perinatal morbidity. In hemophilia A, prenatal and postnatal bleeding may be catastrophic, and modest increments in factor VIII (FVIII) activity are therapeutic. We performed transuterine i.p. gene transfer at day 15 of gestation in a murine model of hemophilia A. Normal, carrier (X(H)X), and FVIII-deficient (X(H)Y and X(H)X(H)) fetuses injected with adenoviral vectors carrying luciferase or beta-galactosidase reporter genes showed high-level gene expression with 91% fetal survival. The live-born rates of normal and FVIII-deficient animals injected in utero with adenovirus murine FVIII (3.3 x 10(5) plaque-forming units) was 87%. FVIII activity in plasma was 50.7 +/- 10.5% of normal levels at day 2 of life, 7.2 +/- 2.2% by day 15 of life, and no longer detectable at day 21 of life in hemophilic animals. Injection of higher doses of murine FVIII adenovirus at embryonic day 15 produced supranormal levels of FVIII activity in the neonatal period. PCR analysis identified viral genomes primarily in the liver, intestine, and spleen, although adenoviral DNA was detected in distal tissues when higher doses of adenovirus were administered. These studies show that transuterine i.p. injection of adenoviral vectors produces therapeutic levels of circulating FVIII throughout the neonatal period. The future development of efficient and persisting vectors that produce long-term gene expression may allow for in utero correction of genetic diseases originating in the fetal liver, hematopoietic stem cells, as well as other tissues.

Adenoviridae↗
PubMed1999

Effect of cigarette smoke on endothelial regeneration in vivo and nitric oxide levels.

BACKGROUND: Cigarette smoking accelerates atherosclerosis and restenosis after vascular reconstruction. The mechanisms by which smoking alters vessel structure after injury are unclear. This study examined the effects of cigarette smoking on endothelial regeneration, an important component of arterial remodeling. MATERIALS AND METHODS: Adult male rats were subjected to balloon injury of the thoracic aorta and exposed to mainstream cigarette smoke via a Griffith-type smoking machine for 2 weeks. Control groups included rats which were restrained in the machine but not smoked and a group not utilizing the machine. Aortic reendothelialization was determined using Evan's blue staining of the arterial surface. Serum levels of nitric oxide were measured to determine if smoke exposure altered this potential endothelial cell mitogen. RESULTS: Cigarette smoking increased aortic endothelial regeneration (78.4 +/- 4.6% vs 59.2 +/- 2.1%, P < 0.05) and was associated with an increase in serum nitric oxide level (59.9 +/- 7. 1 microM vs 28.5 +/- 1.8 microM, P < 0.05). Daily restraint alone in the smoking machine had no effect on endothelial regeneration. CONCLUSIONS: This is the first report on the effects of smoking on endothelial regeneration and demonstrates that smoking increases reendothelialization after large vessel injury and serum levels of nitric oxide, an EC mitogen.

Animals↗