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Biomedical subjects

A Dutta

Publications and source records attributed to A Dutta.

At least 55 records · Page 3Linked to original sources
PubMed2000

Reinforcement of laryngeal mask airway cuff position with endotracheal tube cuff for airway control in a patient with altered upper airway anatomy.

IMPLICATIONS: This case report suggests that the laryngeal mask airway (LMA) cuff position may not be optimal in some difficult airway situations in which the anatomical position of the larynx is altered. Reinforcement of the LMA cuff position by an additional cuff on the dorsal side of the LMA cuff may prove helpful. In this case, in which a difficult airway was anticipated, a nasopharyngeal tube cuff placed behind the standard LMA cuff helped relieve upper airway obstruction.

Adult↗
PubMed2000

Radiation doses during CT fluoroscopy.

CT fluoroscopy (CTF) is a relatively new imaging modality that is particularly useful for performing complex biopsy procedures. Despite the obvious benefits, the potential exists to deliver considerable radiation doses to both the patients and medical staff. The purpose of our study was to quantify the radiation levels based upon typical clinical procedures. To assess the potential radiation risks, the patient radiation doses via the CT dose index (CTDI) method were measured during CTF for a GE Pro-Speed CT scanner using standardized head and body phantoms and a CT ionization chamber. The measurements were performed for a variety of kVp, mA, and slice thickness settings. To determine patient radiation doses, the CT kVp, mA, and total CTF scan times were recorded for various biopsy procedures. To determine the radiation doses to the hands of the radiologists, a radiation survey meter was used to measure the scattered radiation from standard phantoms. The effectiveness of various types of leaded gloves and shields were also determined. The measured CTDI values ranged from 20.4 cGy min(-1) to 63.1 cGy min(-1) of CTF. For a group of 78 patients, the clinically utilized imaging times varied from 13.0 to 407 s with an mean time of 96.6 s +/- 78.9 s (1 standard deviation). The scattered x-ray radiation at the position of the radiologists hands performing the biopsy procedures was measured to be 0.6 to 1.5 mGy min(-1). The thin leaded gloves provided a relatively minimal reduction in the scattered radiation to the hands between 11% and 44% dependent upon the kVp and the type of glove. However, floor mounted radiation shields reduced the scattered radiation levels to the body by 94% to 99%. In comparison to standard x-ray fluoroscopy, CTF employs much higher radiation dose rates due to the higher kVp, mA, and rotating geometry. It is important to minimize the radiation dose to patients and staff by limiting the imaging times, employing lower mA settings, and using appropriate radiation protection measures.

Fluoroscopy↗
PubMed1999

The metazoan origin recognition complex.

Regulated initiation of DNA replication relies on the firing of initiator proteins that bind specifically to origin DNA. The discovery of the first eukaryotic initiator, the Saccharomyces cerevisiae Origin Recognition Complex (ORC) has allowed us to discern some aspects of how the onset of replication is regulated. However, understanding the specifics of replication in metazoan organisms can only be achieved by directly addressing these questions in animal cells. This review deals with the current state of knowledge on the metazoan Origin Recognition Complex, its composition and regulation in higher eukaryotes, its role in the initiation of replication and beyond replication, and its possible connection with human pathology.

Animals↗
PubMed1999

BH-protocadherin-c, a member of the cadherin superfamily, interacts with protein phosphatase 1 alpha through its intracellular domain.

Using a yeast two-hybrid system, we isolated eight cDNA clones which interacted with BH-protocadherin-c (BH-Pcdh-c) from the human brain cDNA library. One clone encoded protein phosphatase type I isoform alpha (PP1alpha) and another two PP1alpha2. PP1alpha was co-immunoprecipitated from the extract of a gastric adenocarcinoma cell line MKN-28 with anti-BH-Pcdh-c antibody. PP1alpha activity towards glycogen phosphorylase was inhibited by the intracellular domain of BH-Pcdh-c. Inhibition of the phosphatase required more than the minimal domain of BH-Pcdh-c which could associate with PP1alpha. In situ hybridization revealed that BH-Pcdh-c mRNA was predominantly expressed in cerebral cortex neurons in the adult mouse brain.

Animals↗
PubMed1999

latheo encodes a subunit of the origin recognition complex and disrupts neuronal proliferation and adult olfactory memory when mutant.

The Drosophila latheo (lat) gene was identified in a behavioral screen for olfactory memory mutants. The original hypomorphic latP1 mutant (Boynton and Tully, 1992) shows a structural defect in adult brain. Homozygous lethal lat mutants lack imaginal discs, show little cell proliferation in the CNS of third instar larvae, and die as early pupae. latP1 was cloned, and all of the above mentioned defects of hypomorphic or homozygous lethal lat mutants were rescued with a lat+ transgene. lat encodes a novel protein with homology to a subunit of the origin recognition complex (ORC). Human and Drosophila LAT both associate with ORC2 and are related to yeast ORC3, suggesting that LAT functions in DNA replication during cell proliferation.

Amino Acid Sequence↗
PubMed1999

Bioelectrical impedance analysis in the evaluation of the nutritional status of continuous ambulatory peritoneal dialysis patients.

The authors evaluated the nutritional status of 47 continuous ambulatory peritoneal dialysis (CAPD) patients, 26 men (age 58.9 +/- 14.6 years, duration on CAPD 27.3 +/- 18.3 months) and 21 women (age 56.2 +/- 14.9 years, duration on CAPD 34.5 +/- 23.4 months), using subjective global assessment (SGA), an established method for the nutritional assessment of dialysis patients, and bioelectrical impedance analysis (BIA: body cell mass, fat mass, and phase angle). Of the studied patients, 19 were diabetic (age 59.7 +/- 13.8 years, duration on CAPD 29.2 +/- 19.7 months) and 28 were non diabetic (age 53.9 +/- 14.3 years, duration on CAPD 31.5 +/- 21.8 months. According to SGA, 24 patients were scored as well nourished (Group I), 18 as mildly malnourished (Group II), and 5 as moderately malnourished (Group III). No patient scored as severely malnourished (Group IV). Analysis of the main nutritional parameters for the subgroups revealed a proportional decrease in phase angle, with a statistically significant correlation (p < 0.009) between phase angle and SGA. No significant difference was seen in serum albumin levels between patients in Group I and Group II, but the mean level was significantly lower in patients in Group III compared to Group I. The nutritional and biochemical data in diabetic patients and non diabetic patients were not significantly different. BIA phase angle seems to be a simple and reliable method for the routine assessment of nutritional status in CAPD patients.

Diabetes Complications↗
PubMed1998

An eukaryotic RuvB-like protein (RUVBL1) essential for growth.

A human protein (RUVBL1), consisting of 456 amino acids (50 kDa) and highly homologous to RuvB, was identified by using the 14-kDa subunit of replication protein A (hsRPA3) as bait in a yeast two-hybrid system. RuvB is a bacterial protein involved in genetic recombination that bears structural similarity to subunits of the RF-C clamp loader family of proteins. Fluorescence in situ hybridization analysis demonstrated that the RUVBL1 gene is located at 3q21, a region with frequent rearrangements in different types of leukemia and solid tumors. RUVBL1 co-immunoprecipitated with at least three other unidentified cellular proteins and was detected in the RNA polymerase II holoenzyme complex purified over multiple chromatographic steps. In addition, two yeast homologs, scRUVBL1 and scRUVBL2 with 70 and 42% identity to RUVBL1, respectively, were revealed by screening the complete Saccharomyces cerevisiae genome sequence. Yeast with a null mutation in scRUVBL1 was nonviable. Thus RUVBL1 is an eukaryotic member of the RuvB/clamp loader family of structurally related proteins from bacteria and eukaryotes that is essential for viability of yeast.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1998

ORC5L, a new member of the human origin recognition complex, is deleted in uterine leiomyomas and malignant myeloid diseases.

A new member of the human origin recognition complex (ORC) was cloned and identified as ORC5L. HsORC5p is a 50-kDa protein whose sequence is 38% identical and 62% similar to ORC5p from Drosophila melanogaster. Two alleles of ORC5L were identified, one with and one without an evolutionarily conserved purine nucleotide binding motif. HsORC5p is precipitated from cell extracts with HsORC2p and HsORC4p, indicating that it is part of the putative human ORC. The bulk of HsORC5p is in an insoluble nuclear fraction, whereas the other known human ORC subunits (HsORC1p, HsORC2p, and HsORC4p) are easily extracted in the nuclear-soluble fractions and in S100 (HsORC1p). In addition, we identified an alternatively spliced mRNA from the same locus (HsORC5T). HsORC5Tp also formed a complex with HsORC4p but not with HsORC2p, suggesting it may play a regulatory role in the assembly of different ORC subcomplexes. HsORC5, HsORC5T, and HsORC4 transcripts are abundant in spleen, ovary, and prostate in addition to tissues with high levels of DNA replication like testes and colon mucosa, implicating the human ORC proteins in functions besides DNA replication. Finally, the gene for ORC5L is located at chromosome 7, band q22, in the minimal region deleted in 10% of uterine leiomyomas and in 10-20% of acute myeloid leukemias and myelodysplastic syndromes.

Alternative Splicing↗
PubMed1998

The human homolog of Saccharomyces cerevisiae CDC45.

In budding yeast Saccharomyces cerevisiae CDC45 is an essential gene required for initiation of DNA replication. A structurally related protein Tsd2 is necessary for DNA replication in Ustilago maydis. We have identified and cloned the gene for a human protein homologous to the fungal proteins. The human gene CDC45L is 30 kilobases long and contains 15 introns. The 16 exons encode a protein of 566 amino acids. The human protein is 52 and 49.5% similar to CDC45p and Tsd2p, respectively. The level of CDC45L mRNA peaks at G1-S transition, but total protein amount remains constant throughout the cell cycle. Consistent with a role of CDC45L protein in the initiation of DNA replication it co-immunoprecipitates from cell extracts with a putative replication initiator protein, human ORC2L. In addition, subcellular fractionation indicates that the association of the protein with the nuclear fraction becomes labile as S phase progresses. The CDC45L gene is located to chromosome 22q11.2 region by cytogenetics and by fluorescence in situ hybridization. This region, known as DiGeorge syndrome critical region, is a minimal area of 2 megabases, which is consistently deleted in DiGeorge syndrome and related disorders. The syndrome is marked by parathyroid hypoplasia, thymic aplasia, or hypoplasia and congenital cardiac abnormalities. CDC45L is the first gene mapped to the DiGeorge syndrome critical region interval whose loss may negatively affect cell proliferation.

Amino Acid Sequence↗
PubMed1998

The evolutionarily conserved zinc finger motif in the largest subunit of human replication protein A is required for DNA replication and mismatch repair but not for nucleotide excision repair.

The largest subunit of the replication protein A (RPA) contains an evolutionarily conserved zinc finger motif that lies outside of the domains required for binding to single-stranded DNA or forming the RPA holocomplex. In previous studies, we showed that a point mutation in this motif (RPAm) cannot support SV40 DNA replication. We have now investigated the role of this motif in several steps of DNA replication and in two DNA repair pathways. RPAm associates with T antigen, assists the unwinding of double-stranded DNA at an origin of replication, stimulates DNA polymerases alpha and delta, and supports the formation of the initial short Okazaki fragments. However, the synthesis of a leading strand and later Okazaki fragments is impaired. In contrast, RPAm can function well during the incision step of nucleotide excision repair and in a full repair synthesis reaction, with either UV-damaged or cisplatin-adducted DNA. Two deletion mutants of the Rpa1 subunit (eliminating amino acids 1-278 or 222-411) were not functional in nucleotide excision repair. We report for the first time that wild type RPA is required for a mismatch repair reaction in vitro. Neither the deletion mutants nor RPAm can support this reaction. Therefore, the zinc finger of the largest subunit of RPA is required for a function that is essential for DNA replication and mismatch repair but not for nucleotide excision repair.

Binding Sites↗
PubMed1998

Genotoxicity of sennosides on the bone marrow cells of mice.

Preparations of a number of plants which contain hydroxyanthraquinones as active constituents are used worldwide for their laxative effect. Anthraquinone glycosides of Cassia angustifolia and C. fistula were investigated for their ability to induce a clastogenic effect on the bone marrow cells of Swiss albino mice. The endpoints screened were chromosomal aberrations and frequency of aberrant cells. Oral exposure to doses of these anthraquinones and their equivalent amount in leaf and pod extracts did not induce significant numbers of chromosomal aberrations or aberrant cells. The results indicate that anthraquinone sennoside B and rhein are weakly genotoxic.

Administration, Oral↗
PubMed1998

Promoting adherence to an electronic home spirometry research program after lung transplantation.

Adherence with any long-term treatment or research protocol is a challenge; this has been found to be the case with lung transplant recipients participating in an electronic home spirometry research program. Because the purpose of the current study is to develop a system for detecting early infection and rejection in lung transplant recipients, regular transmission of data by subjects to the research data center is imperative to the success of the study. Various adherence-promoting strategies have been developed by the research team to increase subject adherence with the program. An increased adherence rate has been reported after implementation of these various strategies, yet work remains to promote continually regular participation in the program by all subjects. It remains a challenge for the research team to devise creative and effective strategies for increasing adherence to regular spirometer use to provide data to develop a computerized system for detecting early infection and rejection of transplanted lung tissue.

Algorithms↗
PubMed1998

Efficacy of oral hyposmolar glucose-based and rice-based oral rehydration salt solutions in the treatment of cholera in adults.

BACKGROUND: Recent animal experiments and clinical trials have shown that both osmolarity and rice as the organic components are important factors for net intestinal absorption of an oral rehydration salt solution. METHODS: In a controlled clinical trial 123 male adult patients with severe cholera, after initial rehydration with intravenous Ringer's lactate solution, were randomly assigned to receive one of the four oral rehydration salt solutions: WHO ORS, ORS containing 70 mmol/l Na+ and 16.2 g/l glucose, rice ORS containing 50 g/l rice and 90 mmol/l Na+, and rice ORS containing 50 g/l rice and 70 mmol/l Na+. All patients received 300 mg of doxycycline as a single dose. RESULTS: Patients who received rice-low-sodium ORS subsequently had lower (P < 0.05) stool output, ORS consumption, and diarrhoea duration than the other three ORS groups. CONCLUSIONS: We conclude that rice-based low-sodium ORS is superior for treating adult cholera.

Adult↗
PubMed1998

Human CDC6/Cdc18 associates with Orc1 and cyclin-cdk and is selectively eliminated from the nucleus at the onset of S phase.

In a two-hybrid screen for proteins that interact with human PCNA, we identified and cloned a human protein (hCdc18) homologous to yeast CDC6/Cdc18 and human Orc1. Unlike yeast, in which the rapid and total destruction of CDC6/Cdc18 protein in S phase is a central feature of DNA replication, the total level of the human protein is unchanged throughout the cell cycle. Epitope-tagged protein is nuclear in G1 and cytoplasmic in S-phase cells, suggesting that DNA replication may be regulated by either the translocation of this protein between the nucleus and the cytoplasm or the selective degradation of the protein in the nucleus. Mutation of the only nuclear localization signal of this protein does not alter its nuclear localization, implying that the protein is translocated to the nucleus through its association with other nuclear proteins. Rapid elimination of the nuclear pool of this protein after the onset of DNA replication and its association with human Orc1 protein and cyclin-cdks supports its identification as human CDC6/Cdc18 protein.

Amino Acid Sequence↗
PubMed1998

Molecular motor and electrokinetic contributions to outer hair cell electromotility.

The outer hair cell of the inner ear is believed to be responsible for the high sensitivity and selectivity of mammalian hearing. Molecular motors are generally believed to cause the electrically-driven length change (electromotility) of the outer hair cell. It has been suggested that electrokinetic effects might also play a significant role in electromotility, along with the molecular motors. This paper describes a new technique that can be used to experimentally determine the percentage of the electromotile response that is caused by electrokinetic effects. The technique is based on the novel idea that molecular motor activity cannot in itself generate a net force on the cell, but that electrokinetic effects can. Our method is the first that can separate molecular motor behavior from electrokinetic behavior, during experiments on the outer hair cell.

Acoustic Stimulation↗
PubMed1998

Cyclin A and MIB1 (Ki67) as markers of proliferative activity in primary renal neoplasms.

Proliferative activity in renal cell carcinomas seems to be a significant predictor of prognosis independent of tumor stage and grade; its correlation with tumor type is not as well studied. We performed immunohistochemical analysis with antibodies directed against Ki67 (MIB1), cyclin A, and cyclin E on 44 renal tumors, including 2 metanephric adenomas, 9 oncocytomas, and 33 renal cell carcinomas, including 10 clear cell, 11 papillary, 6 chromophobe, and 6 sarcomatoid tumors. MIB1 and cyclin A stained between 0 and 23% of tumor nuclei. Reactivity for cyclin E was rare. There was a positive correlation between reactivity for MIB1 and for cyclin A (Spearman rank correlation r = .3587). Reactivity for either MIB1 or cyclin A did not correlate with tumor type, stage, or grade, but reactivity for MIB1 was significantly higher in patients older than 60 years than in patients 60 years of age or younger (P = .046). Proliferative activity as defined by either MIB1 or cyclin A is independent of tumor type, grade, or stage. The proliferative activity of benign renal tumors (metanephric adenoma and oncocytoma) was not significantly different than that seen in renal cell carcinoma.

Adenoma↗
PubMed1998

In vivo cyclin E expression as a marker for early cervical neoplasia.

Identification of human papillomavirus (HPV)-related early cervical neoplasia and its distinction from benign epithelial alterations is based on either subjectively applied morphologic criteria or on identification of associated papillomaviruses. The direct and indirect consequences of HPV infection, however, potentially include upregulation of some host genes. We investigated one candidate, cyclin E, as a possible marker for HPV-related early squamous lesions. Serial paraffin sections from 92 archival cervical biopsy specimens were analyzed, including 19 non-neoplastic biopsy specimens, 30 low-grade and 31 high-grade squamous intraepithelial lesions (SILs), and 12 invasive carcinomas. Four parameters (histologic diagnosis, cyclin E staining, HPV status and, in selected cases, Ki-67 staining) were scored, and their relationship(s) were evaluated by the chi2 independence test. Twenty-one, 73, 79, and 75% of nonlesional epithelia, low-grade SILs, high-grade SILs, and invasive squamous cell carcinomas, respectively, were HPV positive (P < .001 for HPV status vs. diagnosis). Cyclin E staining was nuclear in distribution, and the frequency of positive staining, ie., moderate or strong intensity, was significantly higher (P < .001 for cyclin E staining vs. diagnosis) in all of the lesional epithelia (92.3, 51.6, and 50% of low-grade and high-grade SILs and carcinomas, respectively) compared with nonlesional epithelium (5.9%). Cyclin E positivity and/or HPV positivity was seen in 100% of the low-grade SILs. Epithelial Ki-67 and cyclin E staining were strikingly different in frequency and distribution. Cyclin E was undetectable in basal cells of normal mucosa (which were positive for Ki-67) and limited to suprabasal epithelium in noninvasive lesions. Cyclin E expression correlates strongly with morphologic features of HPV-related preinvasive and invasive cervical disease. This correlation is most pronounced in low-grade SILs. The possibility that in vivo cyclin E staining is a generic marker for HPV infection in low-grade SILs merits additional study.

Biomarkers, Tumor↗