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Biomedical subjects

H Rao

Publications and source records attributed to H Rao.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Osteoblast-like cells cultured in vitro].

OBJECTIVE: To identify the relationship of osteogenesis and osteoblast-like cells from different tissues, and the shape and functional changes of these cells in their different growing stages. METHODS: Three types of osteoblast-like cells, long spindle-shaped, spherical, and squamous cells were obtained from the fetal calvaria of SD rats or Leghorn chickens cultured in vitro. RESULTS: The long spindle-shaped and the spherical cells developed into the squamous cells. They had the same developing tendency and the same results of development. Three types of cells in their different growing stages displayed separately their functional status. They secreted acid mucopolysaccharide, collagen, calcium salt, alkaline phosphatase, etc. The secreted substances heaped up to form new bone tissues. At the same time there were positive acid phosphatase-staining cells around the new bone tissues. CONCLUSIONS: The cells isolated from the fetal calvaria contained two lines of bone cells, carrying out both bone formation and bone resorption.

Animals↗
PubMed1995

Inhibition of the vasopressin-enhancing effect on memory retrieval and relearning by a vasopressin V1 receptor antagonist in mice.

We have previously shown that [Arg8]vasopressin bilaterally administered into the ventral hippocampus of mice at a dose of 0.025 ng/animal 10 min prior to the retention session, improved long-term retrieval processes and relearning of a Go-No-Go visual discrimination task. The purpose of the present study was to determine whether the vasopressin V1 receptor antagonist, -beta-mercapto-beta,beta-cyclopentamethylenepropionyl1, O-Me-Tyr2,Arg8]vasopressin, d(CH2)5Tyr(Me)vasopressin), is able to block the behavioral effect of arginine-vasopressin in the ventral hippocampus. We first tested the effect of three doses of d(CH2)5Tyr(Me)vasopressin (0.025, 1, and 6.3 ng/animal) in the same experimental conditions as used for arginine-vasopressin. The results showed a dose-dependent deleterious effect of the vasopressin V1 receptor antagonist on retrieval and relearning, suggesting the involvement of endogenous arginine-vasopressin in the ventral hippocampus for these memory processes. Second, we tested the ability of d(CH2)5Tyr(Me)vasopressin to block the enhancing effect of experimentally administered arginine-vasopressin. The antagonist was injected at a dose of 0.025 ng, which had no intrinsic effect on behavior, or at a dose of 1 ng, which had a weak deleterious effect on behavior, followed by administration of 0.025 ng of arginine-vasopressin. The results showed that even at the weakest dose (0.025 ng), d(CH2)5Tyr(Me)vasopressin blocked the enhancing effect of arginine-vasopressin on retrieval and relearning. Thus, as for other behaviors and structures, the antagonist microinjected into the ventral hippocampus prevents the enhancing effect of arginine-vasopressin on long-term retrieval and relearning. However, the exclusive involvement of the vasopressin V1 receptors remain to demonstrate vis-a-vis oxytocin receptors.

Animals↗
PubMed1995

Postnatal changes in glutamate binding in the lower medulla of the rat.

Changes in [3H]glutamate (Glu) binding occurring in the lower medulla of the rat between birth (P0) and adulthood (P72) were investigated on cryostat sections using in vitro receptor autoradiography. Densitometric measurements were performed in both autonomic (nucleus tractus solitarii, dorsal motor nucleus of the vagus nerve, ventrolateral medulla) and non-autonomic (inferior olive, spinal trigeminal nucleus) medullary regions. In all these areas, binding densities peaked at P9 and then gradually declined. Values close to those measured in adult animals were reached by P23-P30. These data indicate that glutamatergic neurotransmission within the lower medulla undergoes developmental changes during the early postnatal period. They thereby suggest that the neural circuits essential in organizing autonomic functions are still immature at birth.

Age Factors↗
PubMed1995

The origin recognition complex interacts with a bipartite DNA binding site within yeast replicators.

Replicators are genetically defined elements within chromosomes that determine the location of origins of DNA replication. In the yeast Saccharomyces cerevisiae, the ARS1 replicator contains multiple functional DNA elements: an essential A element and three important B elements--B1, B2, and B3. Functionally similar A, B1, and B2 elements are also present in the ARS307 replicator. The B3 element binds a replication and transcription enhancer protein Abf1p, whereas the A element is required for binding the origin recognition complex (ORC). The function of the B1 and B2 elements remains to be defined. We have used a gel-based DNA binding assay to study the interaction between replicators and the putative initiator protein ORC. In addition to the established requirements for ATP and the A element for ORC-DNA interaction, the new data demonstrate that sequences in the B1 element are also important for ORC-DNA association. This conclusion is supported by DNase I footprint analyses and demonstrates that ORC binds to a bipartitite recognition element within the DNA. Furthermore, mutation of nucleotides in the B1 element suggests that this element has other functions in the initiation of DNA replication besides participating in the ORC-DNA interaction.

Base Sequence↗
PubMed1995

[Megaloblastic changes in cervical epithelium associated with oral contraceptives and changes after treatment with folic acid].

OBJECTIVE: To study the influence of oral contraceptives on cervical epithelium, serum and red blood cell folate levels of users and to observe the changes after treatment with folic acid. METHODS: Morphology of cervical epithelium, serum folate and red blood cell folate levels were studied in 101 women who had used oral contraceptives for over 6 months and 33 intrauterine devices users served as controls, 29 women using oral contraceptives with cervical megaloblastic changes were treated with folic acid (5mg daily) for 3-4 weeks and followed up for observation on morphological changes of cervical epithelium. RESULTS: The mean nuclear diameter of cervical epithelial cells was larger in the oral contraceptive group than that in the control group (P < 0.001). Megaloblastic changes in cervical epithelium occurred in 29 women in the oral contraceptive group (28.7%). There was significant difference in the occurrence of cervical megaloblastic changes between the two groups (P < 0.01). The level of red blood cell folate was lower in the oral contraceptive group than that in the control group (P < 0.05). There was no difference in serum folate, hemoglobin and neutrophil nuclear index between the two groups (P > 0.05). The mean nuclear diameter of cervical epithelial cells decreased significantly (P < 0.001) and multinuclear and vacuolar changes disappeared after folic acid therapy in 26 women with megaloblastic changes. CONCLUSIONS: Oral contraceptives reduced folate storage in the body and resulted in megaloblastic changes in cervical epithelium. This condition was improved with folic acid therapy.

Adult↗
PubMed1994

Functional conservation of multiple elements in yeast chromosomal replicators.

Replicators that control the initiation of DNA replication in the chromosomes of Saccharomyces cerevisiae retain their function when cloned into plasmids, where they are commonly referred to as autonomously replicating sequences (ARSs). Previous studies of the structure of ARS1 in both plasmid and chromosome contexts have shown that it contains one essential DNA element, A, that includes a match to the ARS consensus sequence (ACS), and three additional elements, B1, B2, and B3, that are also important for ARS function. Elements A and B3 are bound by a candidate initiator protein called the origin recognition complex and ARS-binding factor 1, respectively. Although the A and B3 elements have been found in other ARSs, sequence comparisons among ARSs have failed to identify B1- and B2-like elements. To assess the generality of the modular nature of yeast replicators, linker substitution mutagenesis of another yeast chromosomal replicator, ARS307, was performed. Three DNA sequence elements were identified in ARS307, and they were demonstrated to be functionally equivalent to the A, B1, and B2 elements present in ARS1. Despite the lack of DNA sequence similarity, the B1 and B2 elements at each ARS were functionally conserved. Single-base substitutions in the core of the ARS1 B1 and B2 elements identified critical nucleotides required for the function of the B1 element. In contrast, no single-point mutations were found to affect B2 function. The results suggest that multiple DNA sequence elements might be a general and conserved feature of replicator sequences in S. cerevisiae.

Base Sequence↗
PubMed1993

The effect of 5-azacytidine (5-aza-CR) and its analogue on cell differentiation and DNA methylation of HL-60 cells.

The effect of 5-aza-CR and 5-aza-2'-deoxycytidine (5-aza-CdR) on cell differentiation and DNA methylation of HL-60 cells was studied. The differentiation index of HL-60 cells was measured after being treated with drugs by using the NBT stain method. DNA methylase activities of HL-60 cells treated with the drugs were assayed by using 3H-methyl-S-adenosylmethionine (3H-SAM) as a methyl donor. The DNA methylation level of HL-60 cells treated with the drugs was measured by HPLC. The results showed that the HL-60 cell differentiation index was increased after being treated with 5-aza-CR or 5-aza-CdR at a certain concentration for 4 days. But, at the same time, DNA methylase activity and the DNA methylation level were decreased. And all these changes were related to the concentration of the drugs. 5-Aza-CdR was more efficient than 5-aza-CR. We also assayed the E. coli RNA polymerase activity in vitro by using different DNA templets different in DNA methylation level. We found that the transcriptional activity of RNA polymerase was increased with the decrease of the DNA methylation level of HL-60 cells.

Antineoplastic Agents↗
PubMed1992

Synthesis and characterization of a 29-amino acid residue DNA-binding peptide derived from alpha/beta-type small, acid-soluble spore proteins (SASP) of bacteria.

A 29-amino acid residue peptide (SASP-peptide) derived from the sequence of the putative DNA-contacting portion at the carboxyl terminus of an alpha/beta-type small, acid-soluble spore protein (SASP) of Bacillus subtilis has been synthesized by automated solid-phase methods and tested for its ability to interact with DNA. Circular dichroism (CD) spectroscopy reveals an interaction between this SASP-peptide and DNA, both by an increase in alpha-helix content of the peptide (which alone has a mostly random conformation) and by enhancement of the 275-nm CD band of the DNA. In contrast to results with intact alpha/beta-type SASP, however, the peptide does not induce a B----A conformational transition in the DNA. The SASP-peptide also binds to poly(dG).poly(dC) and protects this polynucleotide against DNase I digestion and UV light-induced cytosine dimer formation, parallel to findings made previously with native alpha/beta-type SASP. The results confirm the hypothesis that the carboxyl-terminal region of the alpha/beta-type SASP directly contacts DNA and possesses some, but not all, of the functional characteristics of the intact molecule.

Amino Acid Sequence↗
PubMed1991

Case report: isolated right coronary artery obstruction presenting as acute anterior myocardial infarction.

A patient presented with chest pain and S-T segment elevation in the anterior chest leads diagnostic of acute anterior myocardial infarction (MI). The non-invasive imaging studies showed no evidence of left ventricular anterior MI but showed a right ventricular MI. Coronary angiography showed an isolated right coronary artery obstruction. Occasionally, the ECG in acute right ventricular myocardial infarction may resemble an anterior MI. The differentiation is important from a therapeutic viewpoint.

Adult↗
PubMed1989

Ocular melanoma.

Explore the source record for details and available documents.

Adult↗
PubMed1984

Hepatobiliary imaging in gallstone ileus.

Hepatobiliary imaging was performed in a woman who, at subsequent surgery, was found to have gallstone ileus due to a large gallstone obstructing the proximal jejunum. The triad of findings (failure of the radiopharmaceutical to pass beyond the point of obstruction, marked reflux into the stomach, and nonvisualization of the gallbladder) is nonspecific but, in the appropriate clinical setting, should suggest the possibility of gallstone ileus.

Aged↗
PubMed1984

Immunosuppression promotes ocular virus replication and CNS neurovirulence following corneal inoculation with an avirulent herpes simplex type 1 thymidine kinase negative mutant.

The present study determined the effect of immunosuppression on the pathogenicity of an avirulent HSV-1 thymidine kinase negative mutant in the murine model. Following corneal inoculation with an HSV-1 TK- mutant, normal and cyclophosphamide-immunosuppressed outbred mice were evaluated for keratitis, ocular, trigeminal ganglia, and forebrain virus titers, survival, and latency. Immunosuppression enhanced virus pathogenicity producing greater keratitis, higher ocular, trigeminal, and forebrain virus titers, decreased survival, and increased trigeminal ganglionic residual infectious virus and latency. Our results suggest that both normal host defenses as well as the virus thymidine kinase expression contribute to HSV-1 pathogenicity.

Animals↗
PubMed1983

Hemolytic complement activity in aqueous humor.

Hemolytic C1, C4, C3, and C5 and IgG levels were measured in aqueous humor obtained at surgery from human eyes without inflammation or previous surgery (group 1), eyes with previous surgery (group 2), and eyes with anterior uveitis (group 3). Serum hemolytic complement and IgG levels were also compared with aqueous humor levels. Aqueous humor from eyes in group 1 contained functional C1, C4, C3, and C5, but there was relatively little complement in normal aqueous humor when compared with serum. The mean values of all complement components and IgG in aqueous humor increased from groups 1 to 3; aqueous-serum ratios for each complement component and IgG also increased from groups 1 to 3. Eyes in group 3 had the highest complement and IgG levels and in some cases these values approached those found in serum.

Adult↗
PubMed1983

Thyroid carcinoma after radioiodide therapy for hyperthyroidism. Analysis based on age, latency, and administered dose of I-131.

Twenty-five reports in the medical literature of thyroid carcinomas which were detected after radioiodide therapy for hyperthyroidism were reviewed. These cases did not show a usual characteristic of radiation-associated tumors, namely a long latency period. That is, in 8/25 the latency period was under five years, and the mean latency was only 7.3 years. Further, there was no relationship between latency and age at treatment, or between latency and the dose of radioiodide employed. In 15/25 of the cases, there were known thyroid nodules. Three of the patients had thyroiditis (which itself has a correlation with thyroid carcinoma), and one individual had prior head and neck external radiation. There was no substantiating evidence that radioiodide treatment for hyperthyroidism was the cause of these thyroid carcinomas.

Adenocarcinoma↗