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Biomedical subjects

C L Blanchard

Publications and source records attributed to C L Blanchard.

At least 19 recordsLinked to original sources
PubMed2000

The use of ambient measurements to identify which precursor species limit aerosol nitrate formation.

A thermodynamic equilibrium model was used to investigate the response of aerosol NO3 to changes in concentrations of HNO3, NH3, and H2SO4. Over a range of temperatures and relative humidities (RHs), two parameters provided sufficient information for indicating the qualitative response of aerosol NO3. The first was the excess of aerosol NH4+ plus gas-phase NH3 over the sum of HNO3, particulate NO3, and particulate SO4(2-) concentrations. The second was the ratio of particulate to total NO3 concentrations. Computation of these quantities from ambient measurements provides a means to rapidly analyze large numbers of samples and identify cases in which inorganic aerosol NO3 formation is limited by the availability of NH3. Example calculations are presented using data from three field studies. The predictions of the indicator variables and the equilibrium model are compared.

Aerosols↗
PubMed1999

T cell recognition of hapten. Anatomy of T cell receptor binding of a H-2kd-associated photoreactive peptide derivative.

To elucidate the structural basis of T cell recognition of hapten-modified antigenic peptides, we studied the interaction of the T1 T cell antigen receptor (TCR) with its ligand, the H-2Kd-bound Plasmodium berghei circumsporozoite peptide 252-260 (SYIPSAEKI) containing photoreactive 4-azidobenzoic acid (ABA) on P. berghei circumsporozoite Lys259. The photoaffinity-labeled TCR residue(s) were mapped as Tyr48 and/or Tyr50 of complementary determining region 2beta (CDR2beta). Other TCR-ligand contacts were identified by mutational analysis. Molecular modeling, based on crystallographic coordinates of closely related TCR and major histocompatibility complex I molecules, indicated that ABA binds strongly and specifically in a cavity between CDR3alpha and CDR2beta. We conclude that TCR expressing selective Vbeta and CDR3alpha sequences form a binding domain between CDR3alpha and CDR2beta that can accommodate nonpeptidic moieties conjugated at the C-terminal portion of peptides binding to major histocompatibility complex (MHC) encoded proteins.

Amino Acid Sequence↗
PubMed1997

RNAs 4A and 5 are present in tomato aspermy virus and both subgroups of cucumber mosaic virus.

Primer extension analysis was used to determine the presence of RNAs 4A and 5 in tomato aspermy virus (TAV) and both subgroups of cucumber mosaic virus (CMV). RNAs 4A and 5 were detected in TAV and all CMV strains (representative of both subgroups) that were analysed, except for one subgroup I CMV strain which lacked detectable RNA 5. In subgroup II CMV strains the RNA 5 population was found to consist of two sequence variants. Comparison of the RNA 5 sequences from TAV and CMV indicated that TAV and subgroup II CMV RNA 5 share a much greater degree of sequence similarity than either has with subgroup I RNA 5. RNA 4A and the encoded 2b protein appear to be unique to the cucumovirus genus of the tripartite viruses, which share an otherwise common genome structure, and may have played a role in the evolutionary origin of this genus.

Cucumis sativus↗
PubMed1997

The application of exposure-based criteria in developing alternative primary ambient ozone standards.

The form of the primary National Ambient Air Quality Standard (NAAQS) for ozone has been a matter of some concern in recent years. The Environmental Protection Agency is reviewing the ozone NAAQS and has proposed a set of alternative standards that address some deficiencies. However, the proposed alternatives are all based upon the ozone concentrations occurring at the peak monitor, which may not be representative of the air quality and population exposure throughout a nonattainment area. Representativeness could be improved by converting the form of the standard from an exceedance-based metric (with x allowable exceedances per year, on average) to one based upon exposure. Three approaches to defining an exposure-based standard are developed here. Data from the San Francisco Bay area are used to illustrate the proposed standards.

Air Pollutants, Occupational↗
PubMed1996

Cucumber mosaic virus RNA 5 is a mixed population derived from the conserved 3'-terminal regions of genomic RNAs 2 and 3.

Analysis of encapsidated RNA from the Q strain of CMV (Q-CMV) has indicated the presence of a discreet population of molecules of approximately 300 nt termed RNA 5 (Peden, K.W.C., and Symons, R.H., Virology 53,487-492, 1973.). Q-CMV RNA 5 was isolated and the 5'-end sequence was determined by direct RNA sequencing. This sequence corresponded to the exact beginning of the imperfectly conserved 3'-terminal region of genomic RNAs 1, 2, and 3. A probe generated from RNA 3 consisting of the last 130 nt of this region hybridised to RNA 5. Oligonucleotides containing sequences from the 5'- and 3'-ends of the conserved region were used to generate RNA 5 cDNA clones by RT-PCR on gel-purified RNA 5. Sequencing of these clones and primer extension analysis of transcripts (derived from the cDNA clones) and purified RNA 5 indicated that RNA 5 consists of the conserved 3'-terminal region of genomic RNAs 2 and 3.

Base Sequence↗
PubMed1995

RNA 4 sequences from cucumber mosaic virus subgroups I and II.

The complete sequences of RNA 4 from cucumber mosaic virus (CMV) strains Ny (subgroup I) and Sn (subgroup II) have been determined and compared to all other known complete CMV RNA 4 sequences. The identification of a unique EcoRI site, present only in subgroup-II RNA 4 sequences, provides the basis for a simple method of classifying CMV isolates.

Base Sequence↗
PubMed1991

Rethinking the ozone standard.

Six properties appear desirable for any set of ozone attainment criteria: (1) sufficient stringency to protect public health, (2) simplicity and understandability, (3) sensitivity to real changes in air quality, (4) stability against meteorological fluctuations, (5) use of as much data as possible, and (6) equivalence between the stringency the criteria appear to mandate, and what they actually mandate. We consider how the federal attainment criteria might be improved with respect to Properties 4 through 6 while being equally strong on 1 through 3. Whether the federal standard meets Property 1 has been the subject of debate, but our analysis would apply also to a modified standard. We show that there are subtleties in how improvements might be made. In particular, basing the attainment status on a statistic with low variance may not lead to a more stable criterion, and although it is easy to find a criterion that makes it hard for a district with bad air to reach attainment, or a district with good air to get out of attainment, it is hard to find a criterion that does both. This suggests using different criteria for districts that are out of attainment from districts that are in attainment. Initially the burden of proof would be on the district to prove that its air is of attainment quality. However, once the district has achieved attainment the burden of proof would shift; the district would remain in attainment unless there was strong evidence to the contrary.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗
PubMed1986

Suppression of cellular immunity by head and neck irradiation. Precipitating factors and reparative mechanisms in an experimental model.

A model was developed in C3H mice to investigate the immunosuppressive effects of head and neck irradiation and to explore mechanisms for repair of the defects. Mice receiving 1200 rad (12 Gy) of head and neck irradiation showed significant depression of delayed-type hypersensitivity, peripheral blood lymphocyte counts, spleen cell counts, and spleen cell production of interleukin-2. Treatment with optimal dosages of thymosin alpha 1 (T alpha-1) produced significant increases in all of these values, in some instances to levels higher than in the nonirradiated controls. In identical experiments with mice irradiated to a portal limited to the pelvic region, T alpha-1 induced only partial remission of the abnormalities. The dose response of T alpha-1 with head and neck irradiation showed a relatively limited dose range for immune restoration, a finding that warrants similar determinations in clinical trials with immunomodulating agents. The results suggest a potential clinical usefulness of T alpha-1 and also interleukin-2 in restoring cellular immunity after irradiation for head and neck cancers. The model appears to be useful for investigating immunomodulating agents before they are clinically evaluated as adjuvants with head and neck irradiation regimens.

Animals↗
PubMed1985

Effects of radiation therapy on T-lymphocyte subpopulations in patients with head and neck cancer.

Cellular immunity was assessed in 85 patients with head and neck cancer with monoclonal antibodies to lymphocyte surface antigens that identify total T cells, helper cells, and suppressor cells. The control group consisted of 22 healthy volunteers. Nine patients who had surgical procedures for benign diseases were also studied. Compared with the controls, the patients with cancer who received radiation therapy had a significant decrease in total lymphocytes, T cells, helper cells, suppressor cells, and decreased helper/suppressor cell ratio. Significant decreases in lymphocyte subpopulations were not detected in patients tested before treatment or in patients treated with surgery alone. The immune deficits observed were prolonged in duration, with some present in the patients studied up to 11 years after radiation therapy. This long-lasting immune depression may have relevance to tumor recurrences and second primaries in patients with head and neck cancer treated by radiation therapy and to attempts at increasing cure rates with adjuvant agents that improve immune reactivity.

Carcinoma, Squamous Cell↗
PubMed1984

Acquired inflammatory superior oblique tendon sheath (Brown's) syndrome. Report of a case following frontal sinus surgery.

A case of acquired Brown's syndrome secondary to fibrous proliferation about the trochlea and the superior oblique tendon developed following frontal sinus surgery. This syndrome is a restrictive ocular motility disorder characterized by vertical diplopia and inability to elevate the affected eye above the midline on medial gaze. The purpose of this report is to bring to the attention of otolaryngologists this sequela of sinus surgery, to offer suggestions for modification of surgical technique to avoid this complication, and to emphasize the importance of identifying any signs or symptoms of eye muscle dysfunction prior to surgery.

Adult↗
PubMed1979

Tympanometry in the evaluation of vascular lesions of the middle ear and tinnitus of vascular origin.

The occurrence of vascular perturbations in the tympanogram in association with glomus tumors has previously been noted in the literature. We have broadened the scope of this method of diagnosis in the study of 3 glomus tympanicum and 3 glomus jugulare tumors, 1 dehiscent high jugular bulb, 1 aberrant carotid artery in the middle ear and 2 cases of pulsatile tinnitus of vascular origin. Analysis of illustrative tympanograms at standard and at increased sensitivity (x 20) obtained in these cases are presented. The following factors as they relate to the mechanism of recording the vascular perturbations are presented: air pressure and/or presence of fluid in the middle ear; compliance of the tympanic membrane and ossicular chain as affected by the mass, size and degree of vascularity of the mass and presence of extraneous sounds. A new method of recording the vascular perturbations utilizing a time-base generator affixed to an X-Y plotter is described. It is the purpose of this study to demonstrate the utility of obtaining tympanograms at standard and at increased sensitivity in the evaluation of vascular middle ear lesions and tinnitus of vascular origin.

Acoustic Impedance Tests↗
PubMed1979

Dermoid cysts of the floor of the mouth and lateral neck.

Dermoid cysts of the floor of the mouth and submandibular area represent an unusual clinical entity. We present three such cases and review their clinical presentation and pathologic classification. This study stresses the importance of recognizing and excising any tract leading from such cysts to the midline mandible or hyoid, in order to avoid a recurrence, since these tracts may be epithelialized.

Adult↗
PubMed1978

Use of tragal cartilage with the total ossicular replacement prosthesis.

A method was developed for the use of tragal cartilage and perichondrium with the total ossicular replacement prosthesis. The method involves securing the flat base of the prosthesis in a perichondrial tunnel on the cartilage to stabilize the prosthesis, prevent extrusion, and promote vascularization.

Cartilage↗
PubMed1977

Nystagmus responses to water and air caloric stimulation in clinical populations.

The nystagmus responses of two groups of patients referred for electronystagraphy were compared to test for differences between air and water caloric stimulation. Responses from patients with spontaneous or positional nystagmus or who showed greater than 30% directional preponderance or excitability of labyrinth were removed from the data. The 30 degree C and 44 degree C water and the 24 degree C air produced equivalent responses. The 50 degree C air produced responses with slow component velocities greater than expected; however, the distributions of computed directional preponderance and excitability of labyrinth showed no differences between the air and water caloric stimulation.

Air↗