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Biomedical subjects

H Rao

Publications and source records attributed to H Rao.

At least 19 recordsLinked to original sources
PubMed2005

Impact of hypertension and apolipoprotein E4 on poststroke cognition in subjects >75 years of age.

BACKGROUND AND PURPOSE: The apolipoprotein E4 allele (APOE4) associates with increased dementia risk, and hypertension may associate with mild cognitive deficits. We examined whether nondemented stroke patients with (1) a prestroke history of hypertension and (2) APOE4 were more cognitively impaired at 3 months after stroke. METHODS: A total of 257 participants were genotyped and outcomes from neuropsychological evaluations analyzed using regression. RESULTS: Total Cambridge Assessment for Mental Disorders in the Elderly (CAMCOG) and speed of working memory significantly associated with hypertension. No outcomes significantly associated with APOE4. CONCLUSIONS: Subjects with prestroke hypertension had more impaired global cognition and slower access to information held in working memory.

Age Factors↗
PubMed2004

APOE epsilon4 and cognitive decline in older stroke patients with early cognitive impairment.

BACKGROUND: Dementia is common post stroke, but the potential role of early cognitive impairment and APOE epsilon4 as risk factors is unclear. METHOD: Stroke survivors older than 75 years without dementia at 3 months post stroke received a detailed neuropsychological evaluation at 3 and 15 months post stroke, which included the Cambridge Assessment of Mental Disorders in the Elderly (CAMCOG). Early cognitive impairment was diagnosed using the criteria for cognitive impairment/no dementia (vascular CIND). APOE genotype was determined using a standardized method. RESULTS: One hundred thirty-seven older stroke patients without dementia (mean age 80.6 +/- 4.3, mean CAMCOG score 83.5 +/- 10.4, 68 women) participated in the study, of whom 40 met the criteria for CIND. Stroke patients with one or more APOE epsilon4 alleles were significantly more likely to have CIND (14/40 vs 17/97, odds ratio = 2.5, 95% CI 1.1 to 5.8). Over the 1 year of follow-up, CIND patients with one or more APOE epsilon4 alleles had a mean decline on the total CAMCOG of 2.7 points compared with an improvement of >4 points among patients without APOE epsilon4 (T = 2.9 p = 0.006). CIND patients with an APOE epsilon4 allele also experienced greater decline in memory (T = 2.5, p = 0.015). CONCLUSION: In older stroke patients with early cognitive impairment, the presence of an APOE epsilon4 allele is associated with greater progression of cognitive decline. This has implications for interventions aimed at the secondary prevention of dementia in stroke patients.

Age Factors↗
PubMed2001

Continuum description of rarefied gas dynamics. I. Derivation from kinetic theory.

We describe an asymptotic procedure for deriving continuum equations from the kinetic theory of a simple gas. As in the works of Hilbert, of Chapman, and of Enskog, we expand in the mean flight time of the constituent particles of the gas, but we do not adopt the Chapman-Enskog device of simplifying the formulas at each order by using results from previous orders. In this way, we are able to derive a new set of fluid dynamical equations from kinetic theory, as we illustrate here for the relaxation model for monatomic gases. We obtain a stress tensor that contains a dynamical pressure term (or bulk viscosity) that is process dependent and our heat current depends on the gradients of both temperature and density. On account of these features, the equations apply to a greater range of Knudsen number (the ratio of mean free path to macroscopic scale) than do the Navier-Stokes equations, as we see in the accompanying paper. In the limit of vanishing Knudsen number, our equations reduce to the usual Navier-Stokes equations with no bulk viscosity.

Journal Article↗
PubMed2001

A novel fibronectin binding site required for fibronectin fibril growth during matrix assembly.

Fibronectin (FN) assembly into a fibrillar extracellular matrix is a stepwise process requiring participation from multiple FN domains. Fibril formation is regulated in part by segments within the first seven type III repeats (III1-7). To define the specific function(s) of this region, recombinant FNs (recFNs) containing an overlapping set of deletions were tested for the ability to assemble into fibrils. Surprisingly, recFN lacking type III repeat III1 (FNDeltaIII1), which contains a cryptic FN binding site and has been suggested to be essential for fibril assembly, formed a matrix identical in all respects to a native FN matrix. Similarly, displacement of the cell binding domain in repeats III9-10 to a position close to the NH2-terminal assembly domain, as well as a large deletion spanning repeats III4-7, had no effect on assembly. In contrast, two deletions that included repeat III2, DeltaIII1-2 and DeltaIII2-5, caused significant reductions in fibril elongation, although binding of FN to the cell surface and initiation of assembly still proceeded. Using individual repeats in binding assays, we show that III2 but not III1 contains an FN binding site. Thus, these results pinpoint repeat III2 as an important module for FN-FN interactions during fibril growth.

Animals↗
PubMed2001

Degradation of a cohesin subunit by the N-end rule pathway is essential for chromosome stability.

Cohesion between sister chromatids is established during DNA replication and depends on a protein complex called cohesin. At the metaphase-anaphase transition in the yeast Saccharomyces cerevisiae, the ESP1-encoded protease separin cleaves SCC1, a subunit of cohesin with a relative molecular mass of 63,000 (Mr 63K). The resulting 33K carboxy-terminal fragment of SCC1 bears an amino-terminal arginine-a destabilizing residue in the N-end rule. Here we show that the SCC1 fragment is short-lived (t1/2 approximately 2 min), being degraded by the ubiquitin/proteasome-dependent N-end rule pathway. Overexpression of a long-lived derivative of the SCC1 fragment is lethal. In ubr1Delta cells, which lack the N-end rule pathway, we found a highly increased frequency of chromosome loss. The bulk of increased chromosome loss in ubr1Delta cells is caused by metabolic stabilization of the ESP1-produced SCC1 fragment. This fragment is the first physiological substrate of the N-end rule pathway that is targeted through its N-terminal residue. A number of yeast proteins bear putative cleavage sites for the ESP1 separin, suggesting other physiological substrates and functions of the N-end rule pathway.

Anaphase↗
PubMed2000

Positive findings on bone scan in multiple myeloma.

We report a case of multiple myeloma in which the bone lesions showed high uptake of technetium Tc 99m methylene diphosphonate on a bone scan. A review of the literature comparing the usefulness of conventional skeletal radiography and bone scans in diagnosing the osteolytic lesions of myeloma shows that bone scintigraphy, considered by many to have no role in the detection of osteolytic lesions of myeloma, is in fact more sensitive than radiography in detecting lesions in the ribs, scapula, and spine.

Bone Neoplasms↗
PubMed1999

Postnatal development of synaptophysin immunoreactivity in the rat nucleus tractus solitarii and caudal ventrolateral medulla.

Synaptophysin (SY) is a major integral membrane protein of small synaptic vesicles. In the present study, SY immunohistochemistry was used to investigate the postnatal development of the rat nucleus tractus solitarii (NTS) and nucleus ambiguus/ventrolateral medulla (NA/VLM). Whatever the age of the animal, SY immunoreactivity showed a typical pattern of punctate staining reminiscent of presynaptic terminal labeling. In the NTS and the NA/VLM, SY immunoreactive puncta were few at birth and increased in number during the first postnatal days. These changes were quantified by measuring the volumetric fraction occupied by SY immunoreactive puncta at various postnatal ages. Using volumetric fraction data, an index of the total volume occupied SY immunoreactivity in each region was then calculated. Between birth and adulthood, this index increased by 6-fold in the NTS and by 7-fold in the NA/VLM, suggesting that most of the synaptic development of these regions occurs postnatally.

Aging↗
PubMed1999

Effect of acute high dose dobutamine administration on serum thyrotrophin (TSH).

OBJECTIVE: The interpretation of thyroid function tests in the setting of severe illness is often complicated by concomitant drug administration which may independently produce changes in thyroid hormone concentrations or even secondary hypothyroidism. Although the effects of dopamine on TSH are well established, the effects of dobutamine, another drug commonly used in the setting of severe illness, on TSH are unknown. The aim of the study was to establish the effect(s) of acute high dose dobutamine on serum TSH concentration. DESIGN AND PATIENTS: Thirty subjects undergoing dobutamine stress echocardiogram were compared to twenty controls. Serum TSH was determined between the hours of 0800 and 1000 h at baseline, at maximum dobutamine infusion (20-50 micrograms/kg/min and 15 minutes after stopping dobutamine. MEASUREMENTS: Serum TSH concentration was measured using a third generation chemiluminescent assay. RESULTS: TSH concentration decreased with time in both dobutamine and control subjects and there was an additional statistically significant effect of dobutamine treatment to decrease TSH. TSH concentration remained within the normal range in all subjects who started with normal TSH concentration and remained above normal in the three dobutamine-treated subjects with elevated TSH at baseline. The dobutamine-associated decrease in TSH was still present 15 minutes after discontinuing dobutamine. CONCLUSIONS: These results indicate that acute high dose dobutamine lowers TSH by an unknown mechanism. Additional study with prolonged dobutamine infusion is needed to establish the steady state level and physiological consequences of dobutamine-inhibited TSH.

Adrenergic beta-Agonists↗
PubMed1999

[Detection of Epstein-Barr virus, cell proliferation and apoptosis in thymic tumors].

OBJECTIVE: To investigate the incidence of thymic tumors in Guangzhou, its association with EBV infection and the cell proliferation and apoptosis characteristics of these tumors. METHODS: EBV encoded small RNAs (EBERs) were detected in 43 thymic tumors and 7 thymic hyperplasia samples by use of in situ hybridization, EBNA-1, LMP-1, PCNA, bcl-2 and p53 were examined using immunohistochemical methods, cell apoptosis was evaluated by TUNEL (TdT-mediated dUTP-X nick end labelling) in situ cell death detection kit. RESULTS: 1. Thymic diseases only accounted for 0.057% of biopsies in the Guangzhou area. Thymic tumor and hyperplasia accounted for 74.7% and 18.6% in thymic diseases respectively. Thymic lymphoepithelimoa-like carcinoma (LELC) occurred in 2.7% of thymic tumors. 2. EBV encoded products (EBERs, EBNA-1 and LMP-1) were not detected in 50 thymic disease specimens. 3. Marked proliferation (3+-4+) grade thymomas (0/18 cases) was much lower than that of thymic carcinomas (10/20 cases), and the marked apoptotic (2+-4+) grade was higher in thymomas (15/18) than the thymic carcinomas (13/20). 4. The p53 protein accumulation rate in thymic carcinomas (8/20) was significantly higher than that of thymomas (1/18). The apoptotic grade is significantly related to p53 accumulation in thymic epithelial tumors. 5. The bcl-2 over expression could be detected both in thymomas and thymic carcinomas. CONCLUSIONS: 1. Thymic diseases, including thymic LELC, is very rare in Guangzhou and is not closely associated with EBV infection. 2. Thymic carcinomas have a relatively rapid growth rate compared to thymomas. 3. p53 gene mutation may play an important role in the carcinogenesis of thymic carcinoma, and bcl-2 over-expression may also be involved in the evolution of thymic epithelial tumors. 4. Wild type p53 protein may exert an apoptosis-inducing function in thymic epithelial tumors, including thymomas and carcinomas, and a proliferation inhibiting function only in thymomas.

Adult↗
PubMed1998

Maternal-fetal transmission of human papillomavirus.

OBJECTIVE: To investigate the maternal-fetal transmission of human papillomavirus (HPV). METHODS: Samples of exfoliated cervical cells were obtained from 73 pregnant women on their third-trimester examinations. Samples of fetal membranes, amniotic fluid and nasopharyngeal swab were obtained from the parturients and their neonates. The presence of HPV types 16, 18 and 35 deoxyribonucleic acid was detected by polymerase chain reaction (PCR) and endonuclease method. RESULTS: HPV types 16, 18 and 35 deoxyribonucleic acid were found in 26 (35.6%) of 73 specimens of cervical cells obtained from the parturients, and in 31 (42.5%) of 73 specimens of fetal membranes, 6 (15.4%) of 39 specimens of amniotic fluid, and 5 (14.7%) of 34 neonatal nasopharyngeal swabs obtained from the neonates. The restriction endonuclease analysis of the amplified products showed that HPV types 16, 18 and 35 were positive in 24.7%, 9.6% and 1.4% respectively of parturients, and 11.0%, 4.1% and 0 respectively of neonates. The maternal-fetal transmission rate of HPV was 50% (7/14) for spontaneous vaginal delivery, and 33.3% (4/12) for cesarean section. CONCLUSION: HPV can be transmitted from mothers to their babies not only through the placenta during pregnancy, but also through the genital tract during delivery.

Female↗
PubMed1997

Immunohistochemical detection of glutamate in rat vagal sensory neurons.

Vagal primary afferent neurons have their cell bodies located in the nodose (inferior) and jugular (superior) vagal ganglia and send terminals into the nucleus tractus solitarii (NTS) which lies in the dorsomedial medulla. The presence of glutamate (Glu)-containing neurons in the rat nodose ganglion was investigated using immunohistochemistry. Glu-immunoreactivity on nodose sections was found in neuronal perikarya and nerve fibers, but not in non-neuronal elements such as Schwann cells and satellite cells. Both immunoreactive and non-immunoreactive ganglion cells were observed. The immunoreactive ganglion cells amounted to about 60% of the nodose population. No specific intraganglionic localization was observed for the non-immunoreactive cells. Immunoreactive perikarya were slightly smaller than the non-immunoreactive ones, but no relationship was found between size and staining intensities of immunoreactive neurons. The present data indicate that immunodetectable Glu is present in a large population of vagal afferent neurons. They therefore add to a growing body of evidence suggesting that Glu may be the main neurotransmitter released by vagal afferent terminals within the nucleus tractus solitarii.

Animals↗
PubMed1997

Postnatal ontogeny of glutamate receptors in the rat nucleus tractus solitarii and ventrolateral medulla.

The nucleus tractus solitarii and the ventrolateral medulla are two brainstem regions involved in regulation of autonomic functions. Glutamate (Glu) receptors localized within these two regions play a key role in neural control of swallowing and breathing and in blood pressure regulation. In the present study, postnatal changes in global [3H]Glu binding and in [3H]Glu binding to N-methyl-D-aspartate (NMDA) receptors were analyzed in the nucleus tractus solitarii and the ventrolateral medulla using in vitro receptor autoradiography. Similar results were obtained in both regions. When expressed as density values (fmol/mg tissue), both global and NMDA-sensitive Glu binding increased by approximately 50-70% between birth and postnatal day 9 (P9) and then decreased until P30. When expressed as binding per nucleus (i.e., after correction for tissue growth), global Glu binding still increased between birth and P9 and decreased between P9 and P30 whereas NMDA-sensitive binding increased until P9 and remained stable thereafter. Saturation studies showed a postnatal increase in Glu receptor number per nucleus, which occurred mainly between birth and P9, and a decrease in Glu receptor affinity between P9 and adulthood. These results indicate that dramatic changes in glutamatergic neurotransmission occur in the nucleus tractus solitarii and the ventrolateral medulla during the first month of postnatal life. They suggest that both neonates and young animals may not be fully mature as regard to central regulation of autonomic functions.

Animals↗
PubMed1997

[The significance of detecting EB virus and its products in benign and malignant lymphoepithelial lesions of the salivary glands].

OBJECTIVE: To study the relationship between EB virus and benign malignant lymphoepithelial Lesions (ELEL) and malignant lymphoepithelial lesions (MLEL). METHODS: In situ hybridization, polymeras Chain reaction (PCR) and immunohistochemical methods were used to detect EBV DNA, EBER1 and latent membrane protein 1 (LMP1) on paraffin embedded tissues of 18 MLEL cases and 14 BLEL cases. RESULTS: (1) Positive rates for Bam H1 W fragmet by PCR and EBER1 by in situ hybridization in 18 cases of MLEL were both 100%. Positive rates of EBV DNA by PCR and EBER1 by in situ hybridization in 14 cases of BLEL were both zero percent. (2) LMP1 expression was detected in 77.8% (14/18) of MLEL, EBNA2 was examined in 9 cases of MLEL and no expression was found. (3) Among the infiltrating lymphocytes studied by immunohistochemistry, T cells predominated over B cells in MLEL, B cells predominated over T cells in BLEL. (4) Of the 216 cases of salivary gland cancer, 37 cases could satisfy the criteria for MLEL. The incidence of MLEL in this group was 17.13% (37/216). CONCLUSION: Our results suggest that EBV infection may have some relationship with the genesis of MLEL.

Capsid↗
PubMed1997

[An experimental study of stretching capacity of lens anterior capsule].

OBJECTIVE: To study the stretching capacity of the lens anterior capsule. METHODS: After continuous circular capsulorhexis (CCC) was performed on 22 bull eyes, the capsular elasticity was measured by gradually opening a modified caliper until the capsular opening was torn. The ratio between the circumference of the opening at rupture and that of the original intact one was used as an index of capsular elasticity. RESULT: The circumference of the intact CCC could be enlarged to an additional 61% before a radial tear occurred. The area of the extended CCC was significantly larger than that of the original CCC and than the cross-section of a lens nucleus tilted 30 degrees. CONCLUSION: The anterior capsule was found to have remarkable stretching capacity, and a suitable size of CCC allows a safe removal of lens substance and intraocular lens implantation without radial tears.

Animals↗