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T Young

Publications and source records attributed to T Young.

At least 145 records · Page 8Linked to original sources
PubMed1990

Photo-CIDNP detection of pyrimidine dimer radical cations in anthraquinonesulfonate-sensitized splitting.

Anthraquinone-2-sulfonate (AQS) photosensitizes pyrimidine dimer splitting. Electron abstraction from the dimer is thought to induce dimer splitting, but direct evidence for the existence and intermediacy of dimer radical cations has been lacking. By employing photochemically induced dynamic nuclear polarization, we have found emission signals in the NMR spectra of dimers upon photolysis of dimers in the presence of anthraquinone-2-sulfonate. The two dimers employed were cis, syn-thymine dimer in which the N(1)-positions were linked by a three-carbon bridge and the N(3), N(3')-dimethyl derivative of that compound. The anthraquinone-2-sulfonate sensitized photochemically induced dynamic nuclear polarization spectrum of the methylated derivative exhibited an emission signal from the dimer-C(6) hydrogens. This result implied the existence of a dimer radical cation (mD+.) formed by electron abstraction by excited anthraquinone-2-sulfonate and nuclear spin sorting within a solvent caged radical ion pair [mD+. AQS-.]. Product pyrimidine photochemically induced dynamic nuclear polarization signals were also seen [enhanced absorption by C(6)-hydrogens and emission by C(5)-methyl groups]. Nuclear spin polarization in the product resulted from spin sorting in one or more of its precursors, including mD+. The results support the conclusion that dimer radical cations not only exist but are intermediates in the photosensitized splitting of pyrimidine dimers by anthraquinonesulfonate.

Anthraquinones↗
PubMed1990

Adherence of Mycoplasma hyopneumoniae to cell monolayers.

This work was an attempt to develop an in vitro adherence model for Mycoplasma hyopneumoniae, using monolayers of human and porcine lung fibroblasts and porcine kidney cells. Mycoplasma hyopneumoniae grown in Friis mycoplasma broth was radiolabeled with 35[S]-methionine, washed, concentrated, and inoculated on the monolayers. After 15 minutes of centrifugation to facilitate adherence, monolayers were washed 3 times, dissolved with 0.1N NaOH, and suspended in scintillation liquid, and the radioactivity was determined in a liquid scintillation counter. Adherence, measured as a percentage of counts added, varied according to the mycoplasma strain and the cell line used. Comparison of strains J, 144L, and 232 of M hyopneumoniae revealed 7.5 +/- 5.9, 31.9 +/- 13, and 9.6 +/- 5% adherence to porcine kidney cells, respectively. Slightly different, but proportionally the same relationships were obtained with swine or human fibroblasts. Adherence was decreased slightly by repeated washings of the mycoplasma-treated cell monolayers; however, a plateau was reached, indicating irreversibility of the adherence process. Pretreatment of cell monolayers with nonlabeled organisms substantially blocked adherence by labeled organisms. Dilution of labeled organisms resulted in an increased proportion adhering. Therefore, it appears that the adherence was a receptor-dependent event. Treatment of the mycoplasmas with trypsin prior to the inoculation of monolayers resulted in a marked reduction in adherence. Treatment of the mycoplasmas with hyperimmune swine serum against M hyopneumoniae or normal swine serum resulted in 80 to 90% reduction of adherence; however, no inhibition occurred when mycoplasmas were treated with purified IgG from the hyperimmune serum.

Animals↗
PubMed1989

Are pancarcinoma T and Tn differentiation antigens?

Human fetal tissues were studied for presence of immunoreactive Thomsen-Friedenreich (T) and Tn epitopes (EPs) using well-defined anti-T and anti-Tn rodent monoclonal antibodies. T and Tn are universal (pan) carcinoma (CA) markers that are occluded in normal postfetal tissues except in some immunoprivileged enclaves. Immunohistochemical methods using avidin-biotin immunoperoxidase for staining were employed. Tissues between 45 and 117 days after ovulation were studied. In most instances, anti-T and anti-Tn antibodies showed similar immunoreactivity as demonstrated by positive immunohistochemical staining. The most intense staining was in epithelial and mesothelial components; the mesenchyme stained more faintly. All human sera have anti-T and anti-Tn antibodies, stimulated largely by intestinal flora. The presence of immunoreactive T and Tn during an early phase of fetal development, as shown here, and their known absence in noncarcinomatous postfetal tissues suggests that T and Tn, in addition to their association with CA, are stage-specific oncofetal antigens in pretolerogenic differentiation phases.

Antigens, Differentiation↗
PubMed1989

Free services versus fee for services.

In summary, there are many benefits that can be argued, many risks that can be pointed out, in addressing the question of user charges in community health and social services and institutional services. There is no simple road map for how to make the final political decisions about what charges any government wishes to put in place. As the Ontario government approaches this, it is considering what its options are. It has asked its staff to review current charges to examine what the possibilities are and, in the context of reforming the overall long term care system, will again be looking at some of these questions that I have presented to you.

Community Health Services↗
PubMed1989

Cyclitic glaucoma.

A series of patients is presented showing the widely variable clinical behaviour of different groups of patients who share the common features of cyclitic glaucoma. These cyclitic glaucomas may be classified: 1. Glaucomatocyclitic crises: unilateral or bilateral. This condition presents acutely, almost always in males with a strong tendency to spontaneous resolution but a liability to subsequent recurrence. Some cases are slow to resolve and may recur frequently. 2. Heterochromic cyclitis: glaucoma infrequently complicates heterochromic cyclitis and then with only a mild rise in intraocular pressure (IOP). 3. Chronic cyclitis: unilateral or bilateral. This is more common in females often presenting with a high rise in IOP which may be difficult to control medically. An insidious form of chronic cyclitis occurs in middle-aged, blue-eyed females, often with sarcoid, and is likely to progress to profound visual loss if unrecognised.

Adolescent↗
PubMed1988

Serum and quantitative electroencephalographic pharmacokinetics of loprazolam in the elderly.

This study was undertaken to determine the serum pharmacokinetic parameters of loprazolam, a new benzodiazepine hypnotic, in elderly subjects and to compare these with the kinetics of the drug as determined by quantitative EEG analysis. In addition, a 14-day study was undertaken to determine the steady-state serum levels achieved in this population with repeated drug administration. The study was conducted on 16 male and female subjects between the ages of 62 and 72 years, randomly assigned to two groups treated with 0.5 or 1.0 mg of loprazolam. The serum half-life of loprazolam was found to be 5 hours, and the peak serum concentration was reached after 2 hours. Quantitative EEG changes were observed after 30 minutes suggesting rapid access of the drug into the nervous system. Quantitative EEG changes were evident for 9.5 hours, suggesting the persistent effects of an active metabolite. The 14-day study indicated that loprazolam did not accumulate with continued use.

Aged↗
PubMed1988

Prenatal diagnosis of tetrasomy 47,XY,+i(12p) confirmed by in situ hybridization.

A case of tetrasomy i(12p) detected prenatally is reported. The patient, a black, 32-year-old G3P2002 at 24 weeks' gestation with an unremarkable family history presented herself for prenatal care. Ultrasound examination showed a fetus with diminished femoral and humeral lengths, and hydramnios. A level II scan confirmed the presence of an omphalocele. Amniocentesis at 31 weeks showed 47,XY,+i(12p) karyotype. An infant with multiple congenital anomalies was delivered at 34 weeks. The infant died after 5 h. Genetic and ultrasonographic examinations in the third trimester were helpful in the investigation of this fetus with multiple congenital anomalies. The careful, complete team counselling afforded by this approach enabled the mother and family to be well adjusted to the strong possibility (and subsequent reality) of an abnormal infant.

Adult↗
PubMed1988

Stereotaxic biopsy diagnosis of central nervous system lymphoma.

Twelve cases of central nervous system lymphoma diagnosed by stereotaxic brain biopsy are reviewed to determine the most effective method to establish the diagnosis given the small amount of tissue obtained by this technique. The stereotaxic biopsy material was examined cytologically, histologically, and immunocytochemically. The diagnosis was established by a smear made at the time of biopsy in eight cases. Histologic sections were diagnostic of lymphoma in 11 of 12 cases. Accurate classification according to the Working Formulation was possible in six cases, with diagnosis of diffuse small non-cleaved non-Burkitt's in three, large cell immunoblastic in two, and mixed small and large cell type in one. Five additional cases were diagnosed as high-grade lymphoma but could not be further subclassified because of the small biopsy size or formalin fixation. Immunocytochemical stains for lymphoid markers on paraffin-embedded material confirmed the diagnosis in ten cases, and, in one of these, the demonstration of monoclonality on air-dried cytospins identified an atypical polymorphous lymphocytic population as neoplastic.

Adult↗
PubMed1987

Phase I and pharmacokinetic study of flavone acetic acid.

Flavone acetic acid is the second in a series of compounds based on the flavonoid aglycone ring structure to be clinically evaluated in malignant disease. Preclinical studies have indicated that a minimum plasma level of 150 micrograms/ml is required before therapeutic efficacy (in a wide range of experimental tumors) is seen in mice; both in vitro and in vivo studies also suggest that the duration of drug exposure is crucial in determining activity. Thus a Phase I trial has been performed in a total of 54 patients using 3 schedules, i.e., a 1-, 3-, and 6-h infusion. In each case, treatment was given once weekly for a minimum of 3 weeks. The maximum tolerated doses were 6.4, 6.4, and 10.0 g/m2, respectively. Dose limiting toxicity was denoted by an intense feeling of warmth and flushing with a 1-h infusion, hypotension with a 3-h infusion, and hypotension and diarrhea with a 6-h infusion. No objective responses were seen in this Phase I trial. The recommended doses for Phase II trials of flavone acetic acid in Europe are 4.8 g/m2 over 1 h or 8.6 g/m2 over 6 h. At these doses the peak plasma concentrations obtained are 650 and 388 micrograms/ml, respectively. Total drug exposure (assessed by an area under the curve greater than 100 micrograms/ml) was approximately 50% greater for the 6-h schedule. This Phase I trial indicates that peak plasma concentrations associated with experimental activity are achievable in humans, although optimal drug exposure times have not yet been defined.

Adult↗
PubMed1987

Clinical aspects of phencyclidine (PCP).

The authors provide a comprehensive review of the current phencylidine literature in exploring the history, clinical effects, diagnostic criteria, and treatment of PCP abuse. Seventy-one references are cited.

Humans↗
PubMed1986

Brain imaging in functional mental disorders.

The application of brain imaging techniques to psychiatry is reviewed with respect to computerized tomography (CT), EEG topography, positron emission tomography (PET), and magnetic resonance imaging (MRI). While early computerized tomography studies have suggested structural abnormalities in schizophrenia, more recent studies have shown that most schizophrenics and patients with other disorders have normal CT scans. EEG topography and positron emission tomography have not been evaluated as fully as computerized tomography. However, preliminary studies indicate some functional abnormalities in schizophrenia and affective disorders compared to normal controls. Magnetic resonance imaging shows promise but has had only a limited application to date in psychiatry.

Brain↗
PubMed1985

Unilateral ECT: advantages and efficacy in the treatment of depression.

Electroconvulsive therapy is an efficacious treatment for some acute or drug resistant psychiatric disorders. However, there is some concern with memory impairment and brain damage and in order to decrease these complications, some changes to the technical aspect of electroconvulsive therapy were implemented during the last few decades. One of the major changes is the use of unilateral electrical stimulation on the non-dominant hemisphere which leads to less memory impairment and faster recovery time of cognitive functions. However, for optimal efficacy several variables have to be understood and integrated: electrodes placement, interelectrodes distance, waveform stimuli.

Aged↗