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D Shukla

Publications and source records attributed to D Shukla.

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

Expression of hsp 27, hsp 60, hsc 70, and hsp 70 by immortalized human proximal tubule cells (HK-2) following exposure to heat shock, sodium arsenite, or cadmium chloride.

The expression of hsp 27, hsp 60, hsc 70, and hsp 70 mRNA and protein was determined in immortalized human proximal tubule cells (HK-2) exposed to heat shock, sodium arsenite, or cadmium chloride (CdCl2) under both acute and extended conditions of exposure. It was demonstrated that the HK-2 cells did not exhibit the classic heat-shock response when subjected to an acute physical (heat) or chemical stress (sodium arsenite or CdCl2). Heat stress, elevated temperature at 42.5 degrees C for 1 h, caused a marked increase only in hsp 70 mRNA and protein, but not hsp 27 or hsp 60 mRNA and protein. Similar results were obtained when the cells were subjected to a classic chemical stress of exposure to 100 microM sodium arsenite for 4 h or CdCl2 for 4 h. These findings were in contrast to those found previously with mortal human proximal tubule (HPT) cells, where acute stress by all three stimuli elicited marked increases in hsp 27, hsp 60, and hsp 70 mRNA and protein. It was shown that the basal levels of expression of hsp 27 and hsp 60 in the HK-2 cells were elevated when compared to those found in unstressed HPT cells and that the basal levels were similar to those found in HPT cells under stress conditions. These results suggest that the failure of the HK-2 cells to increase hsp 27 and hsp 60 levels in response to physical and chemical stress is because they already possess elevated basal levels of these proteins. This would indicate that one or more of the genetic events that resulted in the immortalization of the HK-2 cells also elicited a stress response for hsp 27 and hsp 60, but not for hsp 70, stress response family members. Overall, the results suggest that although there are differences in the regulation of the stress response between the immortal HK-2 and mortal HPT cell lines, as long as these differences are recognized, the HK-2 cell line should be a valuable adjunct to study the stress response of the proximal tubule in general and when exposed to environmental pollutants such as cadmium.

Analysis of Variance↗
PubMed2001

Hypothalamic tumour with haemorrhage.

Haemorrhage in low-grade glioma is rare. A 4-year-old boy presented with sudden loss of consciousness. CT scan of his head revealed anterior third ventricular tumour with bleeding, intraventricular haemorrhage and hydrocephalus. The boy expired within 26 h of the onset of his illness, and an autopsy revealed a haemorrhagic juvenile pilocytic astrocytoma arising from the lateral hypothalamus with intraventricular haemorrhage. Intracranial tumour as the cause of sudden death and tumour with bleeding are discussed.

Astrocytoma↗
PubMed2001

Breast mass in a 55-year-old woman.

A 55-year-old white woman presented with a one-month history of a palpable breast mass. A mammogram was performed six months prior to her presentation and was read negative. However, the mammogram done two weeks prior to her clinical visit was suspicious for malignancy. Physical examination revealed a 1.5 cm to 2 cm palpable right breast mass. She underwent excision of the mass. Gross examination of the mass revealed a 2.5 cm well defined, ovoid-shaped, firm tan white tumor with a scalloped border, irregular extension into the surrounding tissue, and a granular cut surface. Largest tumor diameter was 2.5 cm. Microscopic examination of the tumor revealed small tumor cells with a solid, alveolar, and classic "single file" arrangement. There is also focal expansion and filling of the acini by similar small cells.

Breast Neoplasms↗
PubMed2000

Laser flash photolysis evidence for styryl radical cation cyclization in the SET-induced photorearrangement of a p-methoxy-substituted 2-phenylallyl phosphite.

The SET-induced photorearrangement of dimethyl 2-(4-methoxyphenyl)allyl phosphite, 9 (UV light, uranium glass filter, 9,10-dicyanoanthracene (DCA), biphenyl), gives phosphonate 12 in 83% isolated yield. Laser flash irradiation at 355 nm of oxygen saturated solutions of phosphite 9 containing DCA and biphenyl generates the transient UV spectrum of the biphenyl radical cation that is quenched by electron transfer from phosphite 9 (k(q) = 8.9 x 10(9) M(-1) s(-1) at 20 degrees C) to form the 4-methoxystyryl cation 10. The UV spectrum of 10 decays by a measured first-order rate constant of 8.0 x 10(6) s(-1), presumably to generate the cyclic distonic radical cation 11. Intermediate 10 was further characterized by measurement of the second-order rate constants for its reaction with azide, chloride, and bromide ions and with the neutral nucleophile trimethyl phosphite. This study provides the first spectroscopic evidence regarding the proposed mechanism (Schemes 1 and 2) for the SET-induced photorearrangements of dimethyl 2-arylallyl phosphites to the corresponding 2-arylallylphosphonates. Moreover, absolute rate constants for the intramolecular trapping of alkene radical cations have seldom been measured. The removal of the electron from the styryl moiety of phosphite 9, rather than from phosphorus, and the detectability of 10 arise from the stabilizing effect of the 4-methoxy substituent. These results, however, do not allow conclusions to be made concerning the site of removal of an electron in the SET-induced photorearrangement of dimethyl 2-phenylallyl phosphite 1 to phosphonate 6.

Allyl Compounds↗
PubMed2000

Metallothionein isoform 1 and 2 gene expression in the human prostate: downregulation of MT-1X in advanced prostate cancer.

BACKGROUND: Studies have shown an association of metallothionein (MT) overexpression with tumor type and grade. However, a family of genes underlies the expression of these proteins. The goals of this study were to define the expression of MT genes and protein in normal human prostate and to provide evidence that the expression of the MT isoforms is altered in prostate cancer. METHODS: Immunohistochemistry was used to localize MT protein, reverse transcription-polymerase chain reaction (RT-PCR) to determine the MT isoform-specific mRNAs, and immunoblot analysis to determine MT protein levels. RESULTS: The localization of MT in the prostate was further defined using the E9 antibody. Using normal prostate tissue dissected from glands removed for prostate cancer, it was demonstrated that MT protein expression in the normal prostate is supported by mRNA from the MT-1A, MT-1E, MT-1X, and MT-2A genes. No expression of the MT-1X gene was demonstrated in cases of advanced prostate cancer. The expression of MT-1 and MT-2 isoform-specific mRNA varied among three commonly utilized prostate cancer cell lines. CONCLUSIONS: MT protein in the normal human prostate is supported by transcription of mRNA from the MT-1A, MT-1E, MT-1X, and MT-2A genes. Expression of MT-1X mRNA is downregulated in advanced prostate cancer. Variable expression of MT mRNA in prostate cell lines provides evidence that MT gene expression may be altered among individual prostate cancers.

Cell Line↗
PubMed2000

Striking similarity of murine nectin-1alpha to human nectin-1alpha (HveC) in sequence and activity as a glycoprotein D receptor for alphaherpesvirus entry.

A cDNA encoding the murine homolog of human nectin-1alpha (also known as poliovirus receptor-related protein 1 [Prr1] and herpesvirus entry protein C [HveC]) was isolated. The protein encoded by this cDNA proved to be 95% identical in sequence to the human protein and to have similar herpesvirus entry activity. Upon expression of the murine cDNA in hamster cells resistant to alphaherpesvirus entry, the cells became susceptible to the entry of herpes simplex virus types 1 and 2 (HSV-1 and -2), pseudorabies virus, and bovine herpesvirus 1. HSV envelope glycoprotein D (gD), a viral ligand for human nectin-1alpha, is also a ligand for the murine homolog based on evidence that (i) a soluble hybrid protein composed in part of the murine nectin-1 ectodomain bound specifically to purified soluble forms of HSV-1 and HSV-2 gD as demonstrated by enzyme-linked immunosorbent assay, (ii) a soluble hybrid of HSV-1 gD bound to hamster cells expressing murine nectin-1alpha but not to control cells, and (iii) cells expressing both murine nectin-1alpha and one of the alphaherpesvirus gDs were resistant to entry of HSV-1, indicative of interference with entry resulting from interactions of cell-associated gD with the entry receptor. Northern blot analysis revealed that nectin-1 is expressed in most of the mouse tissues examined and at high levels in the brain, skin, and kidneys. Immunocytochemical localization demonstrated the presence of nectin-1 in epithelial cells of the mouse vagina and also in neuronal cells of the central nervous system, suggesting an expression pattern relevant to both infection at a portal of entry and spread of infection to the brain.

Alphaherpesvirinae↗
PubMed1999

Metallothionein isoform 3 expression in the human prostate and cancer-derived cell lines.

BACKGROUND: Expression of metallothionein isoform 3 (MT-3) was initially reported to be confined to neural tissues. However, it was recently demonstrated that MT-3 is expressed in epithelial cells of the human kidney. This motivated the current examination of the expression of MT-3 in the human prostate. METHODS: Immunohistochemistry (IHC) was used to localize the expression of MT-3, RT-PCR to determine the expression of MT-3 mRNA, and Western blot analysis to determine the level of MT-3 protein. RESULTS: Selected epithelial and stromal cells of the normal human prostate were shown to have low levels of MT-3 expression. MT-3 was increased in prostatic intraepithelial neoplasia (PIN) lesions and further increased in a highly variable fashion in prostatic adenocarcinoma. In some adenocarcinomas, MT-3 expression exceeded that of nerve. Three cell culture models of prostate cancer were also shown to variably express MT-3. Restriction enzyme analysis confirmed the expression of MT-3 in the cells and tissues. CONCLUSIONS: MT-3 is expressed in the normal human prostate, and expression is enhanced and highly variable in PIN lesions and primary prostate cancer cells. The variable nature of MT-3 expression was also noted in commonly utilized prostate cancer cell lines.

Amino Acid Sequence↗
PubMed1999

A novel role for 3-O-sulfated heparan sulfate in herpes simplex virus 1 entry.

Herpes simplex virus type 1 (HSV-1) binds to cells through interactions of viral glycoproteins gB and gC with heparan sulfate chains on cell surface proteoglycans. This binding is not sufficient for viral entry, which requires fusion between the viral envelope and cell membrane. Here, we show that heparan sulfate modified by a subset of the multiple D-glucosaminyl 3-O-sulfotransferase isoforms provides sites for the binding of a third viral glycoprotein, gD, and for initiation of HSV-1 entry. We conclude that susceptibility of cells to HSV-1 entry depends on (1) presence of heparan sulfate chains to which virus can bind and (2) 3-O-sulfation of specific glucosamine residues in heparan sulfate to generate gD-binding sites or the expression of other previously identified gD-binding receptors.

Amino Acid Substitution↗
PubMed1999

The murine homolog (Mph) of human herpesvirus entry protein B (HveB) mediates entry of pseudorabies virus but not herpes simplex virus types 1 and 2.

A mouse member of the immunoglobulin superfamily, originally designated the murine poliovirus receptor homolog (Mph), was found to be a receptor for the porcine alphaherpesvirus pseudorabies virus (PRV). This mouse protein, designated here murine herpesvirus entry protein B (mHveB), is most similar to one of three related human alphaherpesvirus receptors, the one designated HveB and also known as poliovirus receptor-related protein 2. Hamster cells resistant to PRV entry became susceptible upon expression of a cDNA encoding mHveB. Anti-mHveB antibody and a soluble protein composed of the mHveB ectodomain inhibited mHveB-dependent PRV entry. Expression of mHveB mRNA was detected in a variety of mouse cell lines, but anti-mHveB antibody inhibited PRV infection in only a subset of these cell lines, indicating that mHveB is the principal mediator of PRV entry into some mouse cell types but not others. Coexpression of mHveB with PRV gD, but not herpes simplex virus type 1 (HSV-1) gD, inhibited entry activity, suggesting that PRV gD may interact directly with mHveB as a ligand that can cause interference. By analogy with HSV-1, envelope-associated PRV gD probably also interacts directly with mHveB during viral entry.

3T3 Cells↗
PubMed1998

Flagellar motor-switch binding face of CheY and the biochemical basis of suppression by CheY mutants that compensate for motor-switch defects in Escherichia coli.

CheY is a response regulator protein of Escherichia coli that interacts with the flagellar motor-switch complex to modulate flagellar rotation during chemotaxis. The switch complex is composed of three proteins, FliG, FliM, and FliN. Recent biochemical data suggest a direct interaction of CheY with FliM. In order to determine the FliM binding face of CheY, we isolated dominant suppressors of fliM mutations in cheY with limited allele specificity. The protein products of suppressor cheY alleles were purified and assayed for FliM binding. Six out of nine CheY mutants were defective in FliM binding. Suppressor amino acid substitutions were mapped on the crystal structure of CheY showing clustering of reduced binding mutations on a solvent-accessible face of CheY, thus revealing a FliM binding face of CheY. To examine the basis of genetic suppression, we cloned, purified, and tested FliM mutants for CheY binding. Like the wild-type FliM, the mutants were also defective in binding to various CheY suppressor mutants. This was not expected if CheY suppressors were compensatory conformational suppressors. Furthermore, a comparison of flagellar rotation patterns indicated that the cheY suppressors had readjusted the clockwise bias of the fliM strains. However, a chemotaxis assay revealed that the readjustment of the clockwise bias was not sufficient to make cells chemotactic. Although the suppressors did not restore chemotaxis, they did increase swarming on motility plates by a process called "pseudotaxis." Therefore, our genetic selection scheme generated suppressors of pseudotaxis or switch bias adjustment. The binding results suggest that the mechanism for this adjustment is the reduction in binding affinity of activated CheY. Therefore, these suppressors identified the switch-binding surface of CheY by loss-of-function defects rather than gain-of-function compensatory conformational changes.

Bacterial Proteins↗
PubMed1995

Mutations leading to altered CheA binding cluster on a face of CheY.

CheY is the response regulator of Escherichia coli chemotaxis and is one of the best studied response regulators of the two-component signaling system. CheY can receive phosphate from the histidine kinase, CheA. Phospho-CheY interacts with the motor-switch complex to induce clockwise flagellar rotation, thus causing the cell to tumble. We used an enzyme-linked immunosorbent assay to study the direct interaction between the kinase, CheA, and the regulator, CheY. The products of random, suppressor, and site-specific cheY mutants were assayed for their ability to bind CheA. Nine mutants showed altered binding. We sequenced and mapped these point mutations on the crystal structure of CheY, and a high degree of spatial clustering was revealed, indicating that this region of CheY is involved in CheA binding. Interestingly, five of these altered binding mutants were previously defined as being involved in motor-switch binding interactions. This suggested a possible overlap between the motor-switch binding and CheA binding surfaces of CheY. Using CheY (Trp-58) fluorescence quenching, we determined the equilibrium dissociation constants of CheA (124-257) binding for these CheY mutants. The results from the fluorescence quenching are in close agreement with our initial enzyme-linked immunosorbent assay results. Therefore, we propose that the CheA and the motor binding surfaces on CheY partially overlap and that this overlap allows CheY to interact with either the CheA or the flagellar motor, depending on its signaling (phosphorylation) state.

Amino Acid Sequence↗
PubMed1990

The primary structure of the virion protein gene and encoded protein of erysimum latent tymovirus.

The nucleotide sequence of the virion protein (VP) gene of erysimum latent tymovirus (ELV) has been determined and the amino acid sequence of the VP deduced and confirmed by peptide analysis. The ELV VP is larger than the VPs of other tymoviruses because it has, unexpectedly, 11 more amino acid residues at its N terminus. The amino acid sequences of the VPs of ELV and four other tymoviruses align unequivocally and their relationships, as assessed from the percentage of identical residues, correlate well with previously reported serological tests which have shown ELV to be distant from other tymoviruses.

Amino Acid Sequence↗
PubMed1987

Electrocerebral silence and nasopharyngeal EEG.

This limited study of six comatose patients who showed clinical signs of brain death was conducted to seek answers to the proposed questions regarding the confirmation of concurrent activity in both scalp and nasopharyngeal electrode tracings, and the detection of any recordable activity from the nasopharyngeal electrodes once no further electrical activity is detected from the surface electrodes. It appears that the nasopharyngeal electrode tracings are as informative as scalp surface electrode tracing is as informative as a scalp surface electrodes tracing in cases of electrocerebral silence. Perhaps a larger patient population testing should be studied to re-affirm this observation.

Brain Death↗
PubMed1980

Hypertensive cerebrovascular disease and normal pressure hydrocephalus.

A hypertensive patient with clinical and laboratory features of normal pressure hydrocephalus (NPH) but with evidence of bilateral multiple cerebral infarcts on computed tomography (CT) did not benefit from shunting. In six reported cases of hypertensive cerebrovascular disease with NPH, the result of shunting was not predictable and was generally disappointing. Laboratory criteria to predict which cases of NPH will benefit from shunting remain controversial. The chances of improvement after shunting are slight when there is CT evidence of bilateral multiple cerebral infarcts, even though other clinical and laboratory data might suggest NPH.

Aged↗