Quantum noise and squeezing in an optical parametric oscillator with arbitrary output-mirror coupling. III. Effect of pump amplitude and phase fluctuations.
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Journal Article↗
Biomedical subjects
S Prasad
Publications and source records attributed to S Prasad.
Human immunodeficiency virus env expression becomes Rev-independent if the env region is not defined as an intron.
The human immunodeficiency virus (HIV) Rev protein functions to facilitate export of intron-containing HIV mRNA from the nucleus to the cytoplasm. We have previously shown that splice site recognition plays an important role in Rev regulation of HIV env expression. Here we have further analyzed the effects of splice sites on HIV env expression and Rev regulation, using a simian virus 40 late replacement vector system. env expression from the vector became completely Rev-independent when an excisable intron was positioned upstream of the env region, provided that env was not recognized as an intron. Complete Rev regulation was restored either by the insertion of a 5' splice site between the intron and the env open reading frame or by deletion of the 3' splice site of the upstream intron. These results show that 5' splice sites can function as cis-acting repressor sequence (CRS) elements to retain RNA in the nucleus in the absence of Rev. They also indicate that Rev regulation of HIV env expression is critically dependent on whether the env region is defined as an intron. This strengthens the hypothesis that Rev interacts with components of the splicing machinery to release splicing factors and enable export of the mRNA before splicing occurs.
Gene Expression Regulation, Viral↗
Localisation of thromboxane A2 receptors and the corresponding mRNAs in human eye tissue.
Thromboxane A2 (TxA2) receptors in human eye sections were identified and localised using a potent TxA2 specific agonist, 125-iodinated 5-heptenoic acid 7-[3-[3-hydroxy-4-[4-(iodo-125I) phenoxy]-1-butenyl]-7- oxabicyclo[2.2.1]hept-2-yl]-,[1S-[1a,2a,(Z),3B(1E,3S*),4a]]-C23 H29 IO5 (125I-BOP) in a binding assay. TxA2 receptors were concentrated in several specific loci within ocular tissues, including the corneal epithelium, the ciliary processes, retina, and posterior ciliary arteries. In addition, we have used the method of in situ hybridisation to observe the distribution of TxA2 receptor mRNA. The distributions of both receptor binding sites and receptor mRNAs showed a close correlation. These studies employed film autoradiography which does not permit cellular resolution. In order to obtain enhanced cellular resolution and more detailed information about the localisation of the receptors and their corresponding mRNAs, emulsion autoradiography was used after ligand binding and in situ hybridisation. This approach showed further that TxA2 receptors are mainly concentrated on non-pigmented epithelial cells of the ciliary processes, on photoreceptors within the retina, and on endothelial cells of the posterior ciliary arteries. These results may be helpful for understanding the pathophysiological effects of TxA2 in the human eye.
Adult↗
Localization of M3 muscarinic receptor subtype and mRNA in the human eye.
Cholinergic agents used to lower intraocular pressure in the medical management of glaucoma act on muscarinic receptors in the eye. Recently, subtypes of muscarinic receptors have been recognized in many tissues including the eye. To localize the M3 muscarinic receptor subtype and m3 messenger RNA (mRNA) in the human eye, we used in vitro ligand binding and in situ hybridization techniques on post-mortem sections. We used an M3 antagonist, [3H]-4-DAMP ([3H]-4-diphenylacetoxy-N-methylpiperidine methiodide) to identify M3-binding sites and a [35S]-labelled oligonucleotide probe to detect and localize m3 mRNA. M3 and m3 mRNA were both localized in the ciliary muscle, ciliary epithelium, iris, corneal epithelium and anterior lens epithelium. The m3 transcript was also detected in the trabecular meshwork and corneal endothelium.
Acetylcholine↗
Efficacy of surgical treatments for squamous cell carcinoma of the temporal bone: a literature review.
A review of all publications dealing with surgical treatment for squamous cell carcinomas of the temporal bone was performed. No randomized or nonrandomized control studies were identified. All studies were case series without control subjects. Twenty-six of 96 publications, which contained information on 144 patients, were analyzed. Several inferences are suggested by the available evidence; however, these areas should be investigated by properly designed randomized clinical trials: (1) patients with carcinoma that is confined to the external auditory canal have similar survival, regardless of whether mastoidectomy, lateral temporal bone resection (TBR), or subtotal TBR is performed: the addition of radiation therapy to lateral TBR does not appear to improve survival; (2) when disease extends into the middle ear, survival of patients treated with subtotal TBR appeared to be improved over those treated with lateral TBR or mastoidectomy: it remains uncertain if the addition of radiation therapy to mastoidectomy improves survival; (3) the value of surgical resection when carcinoma extends to involve the petrous apex remains unclear; (4) resection of involved dura mater does not appear to improve survival; however, incomplete data regarding margins of resection were reported; and (5) determination of the value of resection of involved brain parenchyma or internal carotid artery will require further study.
Brain Neoplasms↗
Case report: radiology of stromal sarcoma of the breast with ossifying pleural metastases.
Stromal sarcoma of the breast is a rare tumour, the radiology of which has not been to our knowledge properly documented: the case presented returned to medical attention with a large, apparently calcifying pulmonary mass. This proved to be an ossifying pleural metastasis at thoracotomy, when a second smaller, unsuspected similar lesion was found. The radiological findings (including mammography and CT) are reviewed. The role of the radionuclide bone scan (the full significance of which was not appreciated preoperatively) is discussed.
Aged↗
Postequatorial horizontal rectus recession in the management of congenital nystagmus.
Postequatorial (12 mm) recession of all four horizontal recti was done in nine patients with congenital nystagmus. Fifteen of 18 eyes showed decreased amplitude of nystagmus while 12 eyes also showed an increase in visual acuity. Functionally, significant limitation of ocular motility was not encountered despite unconventionally large recessions.
Adolescent↗
Guidance of filopodial extension by fibronectin-rich extracellular matrix fibrils during avian gastrulation. A study using confocal microscopy.
We have used double-label confocal microscopy to examine the relationships between the orientation of filopodial extension in mesoderm cells and the orientation of fibronectin-rich extracellular matrix fibrils during chick embryo gastrulation. We fluorescently labeled mesoderm tissue dissected from donor embryos by immersion in carboxyfluorescein and then grafted it into unlabeled host embryos at the same stage of gastrulation. After further incubation, the host embryos were fixed, the endoderm removed, and the extracellular matrix was immunostained with antibodies to fibronectin conjugated to Texas Red. We found that both the general shape of the mesoderm cells and the orientation of filopodial extension were influenced by the surrounding matrix fibrils. Elongated shape was associated with individual fibrils which impinge on only one side of the cell. Similarly, filopodial extension followed a single fibronectin-rich fibril, although filopodia were also observed to be channeled between pairs of parallel fibrils. Cells attached to non-aligned regions of substratum showed no polarity. The mesoderm cells themselves apparently synthesize their own fibronectin, and deposit this on the cell surface not attached to the substratum. We conclude that individual fibronectin-rich substratum fibrils, in the size range 0.7-2.8 microns, are able to exert contact guidance on the mesoderm cells, despite the production of endogenous fibronectin by the cells themselves. These results support the contention that contact guidance is a physiological mechanism influencing the orientation and directionality of cells during the morphogenetic movements of embryogenesis.
Animals↗
Poly(ADP-ribose) polymerase in HeLa cells--a high resolution two-dimensional gel analysis.
PADPRP is an eukaryotic enzyme responsible for poly(ADP-ribosyl)ation of several chromatin-associated proteins. Consequently, the modified proteins acquire various lengths of negatively charged, covalently bound oligo or poly(ADP-ribosyl) homopolymers. The present study was undertaken to get an insight into the charge and size heterogeneity of the various auto-modified species of PADPRP and other protein acceptors of (ADP-ribose) polymers. Toward this end, we analyzed HeLa cells using high resolution two-dimensional gel electrophoresis (2D-PAGE). Resolution of HeLa total cellular lysates in the basic pH range combined with immunoblots and activity-blots revealed extensive modification and processing of the enzyme. In addition to the native enzyme, a protein of approximately 116 kDa, we observed several proteins that exhibit immunoreactivity to an antibody prepared against a peptide encompassing the N-terminal 20 amino acids of the polymerase. Several protein species showed auto-modifying potential in an in situ activity blot assay. We have also localized the ADP-ribosylated proteins in permeabilized HeLa cells to demonstrate protein acceptors of poly(ADP-ribose).
Adenosine Diphosphate Ribose↗
Double ureters in renal transplantation: our technique.
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Follow-Up Studies↗
Management of multiple arteries in renal transplantation.
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Anastomosis, Surgical↗
Identification and structural characterization of the 75-kDa rabbit zona pellucida protein.
A cDNA (rc75) encoding a 75-kDa rabbit zona pellucida (ZP) glycoprotein (R75) has been cloned and sequenced. The predicted amino acid sequence consists of 676 amino acids including seven potential N-glycosylation sites. The cDNA hybridizes to a 2.4-kilobase mRNA in ovary that is not detectable in other rabbit tissues. The R75 mRNA was also found to be expressed during the early stages of rabbit ovarian development (2-6 weeks of age) when the ovary contains primordial, primary, and early secondary follicles. The deduced amino acid sequence of rc75 has 77% similarity to the mouse ZP2 protein but no similarity to mouse ZP3. R75 also contains regions with 35-55% similarity to a previously cloned rabbit 55-kDa ZP protein. Monte Carlo simulation comparison confirmed that R75 has a significant probability of homology with mouse ZP2 and the rabbit 55-kDa ZP protein. Antibodies were developed against a fragment of R75 (rc75a cDNA) expressed in the pEX expression vector. These antibodies were used to confirm that the expressed protein contained epitopes found in the native rabbit ZP glycoprotein. These data suggest that some, but not all, ZP proteins may be conserved among different species and that within a species ZP proteins may share similar regions.
Aging↗
Immunocytochemical localization of sodium channels in an insect central nervous system using a site-directed antibody.
Antibodies to channel proteins and specific peptide sequences have been previously used to localize voltage-activated sodium channels in the rat brain. Here we describe the first localization of sodium channels in an insect nervous system using a site-directed antibody. The mesothoracic ganglion of the cockroach was stained with an antibody to the highly conserved SP19 sequence. Antibody labelling was visualized by light microscopy using the avidin/biotin method on wax sections, and transmission electron microscopy of immunogold-labelled thin sections. Central ganglia of insects contain clearly separated regions of cell bodies, synaptic neuropil, axon tracts, and nerves. Antibody staining by light microscopy was limited to neurons, and was intense in axons throughout the ganglion and nerves. Staining was also strong in the cytoplasm, but not the nuclei, of many neuronal cell bodies. Neuropil regions were relatively lightly labelled. These findings can be correlated with the known electrophysiology of the ganglion. Electron microscopy detected sodium channels in areas surrounding axons, probably including axon membranes and enveloping glial cell membranes. Axonal mitochondria were also heavily labelled, suggesting a sodium channel transport function for these organelles.
Amino Acid Sequence↗
The involvement of TGF beta 1 in early avian development: gastrulation and chondrogenesis.
We examined the effects of transforming growth factor-beta 1 (TGF beta 1) and a neutralizing monoclonal antibody on two phases of early chick embryo development: gastrulation and chondrogenesis. We carried out experiments in vivo and in vitro on mesoderm cells from the gastrulating embryo at day 1, and on sclerotome cells from day 3 embryos, having previously shown that this factor is present among these cells at these stages of development. Addition of the antibody to cultures of these cells produced a dose-dependent decrease in cell out-growth and spreading and concomitantly reduced fibronectin deposition. In vivo studies of the effects of TGF beta 1 on mesoderm during gastrulation were carried out by grafting beads carrying this agent into gastrulating embryos. We used beads of ion-exchange resin as well as hydrolysed polyacrylamide, and found that the grafts produced an accumulation of mesoderm cells around the implant and, at later stages, the formation of enlarged somites. There was no effect on embryonic axis formation. Studies of bromodeoxyuridine (BrdU) incorporation indicated that the mesoderm accumulation was due, at least in part, to an increase in cell proliferation. However, examination of the effect of TGF beta 1 on BrdU incorporation by mesoderm during gastrulation and sclerotome cells in vitro indicated in inhibition of cell proliferation, an inconsistency explained in terms of the variation between the in vivo and in vitro conditions. We conclude that TGF beta 1 is both appropriately located, and is able, to influence cell proliferation among the mesodermal cell populations during early development, and that this effect contributes to the overall control of mesodermal morphogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The biologic activities of peptidoglycan in experimental Haemophilus influenzae meningitis.
While gram-positive bacterial cell walls are known to incite inflammation, the contribution of gram-negative peptidoglycan to disease has not been characterized. The ability of cell wall, purified peptidoglycan, and soluble peptidoglycan subcomponents from Haemophilus influenzae to provoke inflammation was determined in a rabbit model of meningitis. Haemophilus peptidoglycan, with or without associated proteins, produced brain edema at > or = 0.1 micrograms/mL of cerebrospinal fluid (CSF); leukocytosis and protein accumulation in CSF occurred only at > or = 10.0 micrograms/mL of CSF. Solubilized peptidoglycan was 10-fold more active than intact cell wall. The bioactivity of peptidoglycan from ampicillin-resistant H. influenzae was at least twofold greater than that of ampicillin-sensitive strains. Consistent with these pathologic effects of purified peptidoglycan, ampicillin-induced bacterial lysates in which endotoxin was neutralized induced brain edema and protein influx but little leukocytosis. Thus, peptidoglycan seems to contribute to the pathology of gram-negative meningitis, particularly brain edema.
Ampicillin Resistance↗
Neurilemmoma (schwannoma) of the facial nerve presenting as a parotid mass.
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Adult↗
Results of revision stapedectomy for conductive hearing loss.
Revision stapedectomy operations performed over a 13-year period (1977 to 1990) for a conductive hearing loss are reviewed in terms of intraoperative findings and hearing results. All operations were performed in a conventional manner without use of laser techniques. A management algorithm based on intraoperative findings is described. Results are compared with previously reported series. The 66 cases include 20 males and 46 females, ranging in age from 8 to 73 years. Mean time between original and revision stapedectomy was 12.5 years. Prostheses encountered at time of revision included wireloop (29), Robinson (18), polyethylene (14), other (3), and two were not found. The most common cause of failure was displacement of the prosthesis. Incus erosion was found in 48% of wireloops, 35% of polyethylene, and only 11% of the Robinson prostheses. Revision resulted in closure of the pure-tone average (PTA) air-bone gap to within 10 dB in 46% and to within 15 dB in 76%. Sensorineural hearing loss (> 10 dB) occurred in 5 cases (7.6%), and a decline in speech discrimination (> 10%) occurred in 17%. Three of four cases requiring drillout had gap closure to within 10 dB. Findings suggest that our management technique produces results comparable to other large reported series. Drillout at the time of revision can be recommended.
Adolescent↗
Facial nerve function following cerebellopontine angle surgery: prognostic value of electroneurography.
Preoperative counseling of patients, regarding facial nerve function following cerebellopontine angle (CPA) surgery, has remained a difficult task. Facial nerve electroneurography (ENoG) or evoked electromyography can detect subclinical neural degeneration. This test was used in 44 patients undergoing CPA surgery, and facial nerve function was followed postoperatively. A normal preoperative ENoG study appeared to predict an 81 percent and 84 percent chance of good (House grade I-II) early and late postoperative facial function, respectively. An abnormal test is not as reliable. The relation of preoperative ENoG results with tumor size and tumor adherence to the facial nerve is investigated. Electroneurography appears to be a useful preoperative test when counseling patients regarding facial function following CPA surgery.
Adult↗