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D Williams

Publications and source records attributed to D Williams.

At least 487 records · Page 27Linked to original sources
PubMed1985

Effects of corticosterone and 5 alpha-dihydrocorticosterone on brain excitability in the rat.

The effects of corticosterone (B) and its reduced metabolite 5 alpha-dihydrocorticosterone (DHB) on CNS activity in the rat were examined. Two indices of brain excitability were evaluated: 1) amplitude of population responses (evoked potentials [EP] to sciatic nerve stimulation) and 2) changes in the rate of firing of tonically discharging neurons--both at pontine brainstem regions of the reticular formation. Experiments were carried out in adrenalectomized rats, and recordings were obtained from animals under urethane anesthesia. Steroids were dissolved in a 4:1 saline:Cremophor-El (Sigma) solution and doses of 750 micrograms/0.5 ml were injected (IV). The effects of B on EPs were bidirectional. Increases (8 animals) and decreases (6 animals) of the amplitude responses in different animals were observed. In 4 animals, no changes were detected. In contrast, injection of DHB produced a consistent and significant reduction of brainstem sciatic evoked potentials in 10 of 12 animals tested; 2 animals did not respond to the steroid. At the neuronal level, the effects of the steroids were evaluated by the changes they induced in the mean firing frequency (P less than 0.01) measured during 5-min intervals as determined by a one-way analysis of variance and analysis with a test of multiple comparisons. Only cells that fired in a stationary mode for 15 min before the steroid injection were studied. A more consistent pattern of responses to B was observed at the single-cell level. From 31 neurons that responded to the hormone, of 76 examined, 27 showed an increase in their firing rate and only 4 neurons showed a decrease. The increase in firing rate had an onset latency of 2-5 min (means = 3.5, SE 0.43) with a duration of 16-25 min (means = 17.5, SE 2.7). Of 69 neurons that were tested with DHB, 51 showed a significant decrease in their mean firing frequency. Onset latency of the effect was 2-8 min (means = 4.0, SE 1.21) and the duration of the induced changes was 16-40 min (means = 30.0, SE 3.47). Central interactions of DHB and B when sequentially administered were examined in 28 neurons. Of these, 21 responded to DHB administration with a significant decrease in their firing rates. In 11 of these neurons, injection of B, 5 min after DHB, was followed by a rapid (1-2 min) return of the neurons to baseline firing rates.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1985

Visual motion, binocular correspondence and binocular rivalry.

Human observers dichoptically viewed displays consisting of isotropic random dots, with the dots in each eye's view all moving in a given direction or appearing stationary. When the interocular difference in direction of motion was less than 30 deg, a stable, fused percept resulted. Once this interocular difference was exceeded, binocular rivalry ensued. Rivalry was also obtained when dots seen by the two eyes moved in identical directions but at different velocities. Under this condition, the proportion of time that rivalry was experienced increased with the interocular difference in velocity. Moving dots predominated over stationary ones, and when both sets of dots moved there was no clear advantage of one speed of motion over the other. Contrary to some earlier reports, these results show that motion is not immune to binocular rivalry. Evidently the process responsible for establishing binocular correspondence between images received by the two eyes is sensitive to disparities in direction and velocity of motion.

Functional Laterality↗
PubMed1985

Transient blindness following transurethral resection of the prostate in an achondroplastic dwarf.

Neurological complications associated with transurethral resection of the prostate have been reported in the past. We report on an achondroplastic dwarf who suffered transient blindness following transurethral resection of the prostate. The blindness correlated with a markedly elevated serum glycine level of 13,734 mumol. per l. We discuss the possibility of glycine being responsible for this complication.

Achondroplasia↗
PubMed1985

The role of fiberoptic bronchoscopy in the evaluation of immunocompromised hosts with diffuse pulmonary infiltrates.

To define the utility of fiberoptic bronchoscopy in the evaluation of immunocompromised patients with diffuse pulmonary infiltrates, we reviewed our experience between January 1980, and January 1983, with 50 such patients with a wide variety of underlying diseases. Of these, 35 patients underwent bronchoscopy, including brushings, alveolar lavage, and transbronchial biopsy, and 15 underwent open lung biopsy; 8 patients underwent both procedures. All patients with a nondiagnostic bronchoscopy either recovered without specific antibiotic therapy or underwent an open procedure. A diagnosis was made in 29 patients (58%). An infectious process was found in 20 patients (40%). A diagnosis was made bronchoscopically in 19 patients including 18 infections. Transbronchial biopsy was rarely diagnostic of infection when brushings were negative. For all diagnoses, bronchoscopy had a sensitivity of 76.9%. For all pulmonary infections, bronchoscopy had a sensitivity of 90%. Given a negative bronchoscopy, the probability that an infection was not present (i.e., predictive value negative) was 94.4%. Unfortunately, making a specific diagnosis did not appear to greatly improve survival. We conclude that in this setting: (1) fiberoptic bronchoscopy is an extremely sensitive procedure for diagnosing pulmonary infections, (2) bronchial brushings are as useful as transbronchial biopsies for diagnosing nonfungal infections, (3) these procedures are less useful for diagnosing noninfectious conditions, and (4) in the face of a negative bronchoscopic procedure, there is a very low probability that an infectious process will be found with an open biopsy.

Adult↗
PubMed1985

Acute mixed lineage leukemia: clinicopathologic correlations and prognostic significance.

The frequency and clinical significance of acute leukemia displaying both lymphoid and myeloid characteristics was determined in 123 consecutive children using a panel of lineage-associated markers. The leukemic blasts from 18 of 95 children (19%) with the diagnosis of acute lymphoblastic leukemia (ALL) by standard diagnostic criteria expressed myeloid-associated cell surface antigens. Despite immunological evidence of lymphoid differentiation (17 CALLA + and one T cell-associated antigen +) and findings of immunoglobulin gene rearrangement, blasts from these patients reacted with one to five monoclonal antibodies identifying myeloid-associated cell surface antigens (My-1, MCS.2, Mo1, SJ-D1, or 5F1). Dual staining with microsphere-conjugated antibodies and analysis by flow cytometry confirmed that some blasts were simultaneously expressing lymphoid- and myeloid-associated antigens. Conversely, blasts from seven of 28 patients (25%) with acute nonlymphocytic leukemia (ANLL), diagnosed by otherwise standard morphological and cytochemical criteria, expressed lymphoid-associated surface antigens. Dual staining of individual blasts demonstrated simultaneous expression of myeloperoxidase (MPO) (including Auer rods) in association with either T-11, CALLA, or terminal deoxynucleotidyl transferase. Blasts from one patient with ANLL demonstrated T cell receptor gene rearrangement, while blasts from another patient demonstrated characteristics associated with T (T-11), B (CALLA and heavy-chain immunoglobulin gene rearrangement), and myeloid (MPO) lineage. There were no consistent cytogenetic abnormalities, and no patient demonstrated independent leukemic clones. Each patient with typical ALL, except for myeloid-associated antigens, achieved complete remission with conventional induction therapy for ALL. By contrast, three of the seven children with ANLL whose blasts expressed the T-11 surface antigen failed ANLL induction therapy. These three patients subsequently achieved remission with ALL therapy.

Acute Disease↗
PubMed1984

Identification and purification of a 55K polypeptide in Sjögren's syndrome A antigen.

The Sjögren's syndrome A antigen (SS-A) purified by affinity chromatography from human spleen was shown to contain a major polypeptide with a mol. wt. of 55 000 daltons confirmed as SS-A by its reactivity with different anti-SS-A sera on affinity columns, immunodiffusion and the Western blot. A similar reactive polypeptide was demonstrated in extracts of rabbit liver, brain, spleen, kidney, lung and thymus.

Animals↗
PubMed1984

The pulmonary arteries of the yak.

A quantitative histological study was carried out on the pulmonary arteries of a female yak (Bos grunniens), a member of the genus Bos which comprises the various types of cattle. A characteristic feature of cattle is a muscular pulmonary vasculature which responds sensitively to alveolar hypoxia by constriction. The yak studied had thin-walled pulmonary arteries and showed no evidence of right ventricular hypertrophy. It is suggested that this may be a feature of adaptation (as contrasted to acclimatisation) to a life in the hypobaric hypoxia of high altitude.

Adaptation, Physiological↗
PubMed1984

Underwater weighing using the Hubbard tank vs the standard tank.

The purpose of this study was to determine whether underwater weighing in the Hubbard tank is a valid and reliable method for estimating body composition. Thirty healthy subjects were weighed underwater for four separate trials; each trial consisted of five weighings. The first trial was completed in a standardized sit-in underwater weighing tank, and the last three trials were completed in a Hubbard tank. Validity was determined by calculating Pearson's correlation coefficient across the four underwater trials, which resulted in r = .077 or higher. The coefficient of variation was found to be 1.22 percent for the sit-in tank and 1.23 percent for the Hubbard tank. A paired t test between the two methods was significant at the .001 level. Reliability for the Hubbard tank method was determined by the repeated measures analysis of variance across the three trials and found not to be significant. The intraclass correlation for the three Hubbard tank trials resulted in R = .997. In addition, the interrater reliability between the two researchers who made independent observations of the weight scale resulted in r = .999 for the standardized sit-in tank and r = .998 for the Hubbard tank. Therefore, the Hubbard tank appears to be valid, reliable, and equally effective as the standardized sit-in underwater weighing tank for determining body composition. Because the paired t test was significant, however, the two methods should not be interchanged; one or the other method should be used, but not both.

Adipose Tissue↗
PubMed1984

Sudan black B positive acute lymphoblastic leukaemia.

The presence of greater than 3% Sudan black B (SBB) positivity in leukaemic blasts has been considered diagnostic of acute non-lymphocytic leukaemia (ANLL). A rare report has indicated that this finding may not be specific for ANLL. In order to determine whether SBB could be found in acute lymphoblastic leukaemia (ALL) the data on 350 patients with newly diagnosed ALL were reviewed. Six patients (1.6%) were found to have 5% or greater SBB positive blasts. The diagnosis of ALL was supported by morphology, cytochemistries, immunologic markers, therapeutic response, and in one case immunoglobulin gene rearrangement. It is important to recognize the fact that SBB is not specific for AML and may be found in the blasts of patients with ALL.

Adolescent↗