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Biomedical subjects

T Oliver

Publications and source records attributed to T Oliver.

At least 37 records · Page 2Linked to original sources
PubMed1999

Width/length ratios of normal clinical crowns of the maxillary anterior dentition in man.

The purpose of this investigation was to analyze the clinical crown of the 3 tooth groups of the maxillary anterior sextant of the permanent dentition of normal subjects with respect to (i) width, length and the width/length ratios and (ii) determine if there is a correlation between tooth dimensions or tooth group ratios and subject height. Subjects (> or = 20 y.o.) were recruited for this study if (i) the free gingival margin on the facial surface of teeth in the maxillary sextant was positioned apical to the cervical bulge, (ii) there was no evidence of attachment loss; as determined by lack of a detectable CEJ and (iii) the marginal tissue was knife edged in form, firm in consistency and coral pink in color. Teeth were excluded if (i) there was evidence of gingival alteration, i.e., gingival overgrowth/hyperplasia, inflammation, altered passive eruption, attachment loss, gingival recession or history of periodontal surgery, or (ii) there was evidence or history of incisal edge/proximal tooth alteration as in, i.e., restorative intervention, traumatic injury or occlusal wear into dentin. At least 1 suitable tooth from each tooth group of the maxillary anterior dentition had to be present. A maxillary impression was taken and poured in yellow die stone. The widest mesial-distal portion and the longest apical-coronal portion of the test teeth were measured. Gender, ethnicity and subject height (SH) were recorded for each participant. Due to a limited ethnic diversity only data from the Caucasian group were analyzed. The mean coronal tooth width (mm) of males versus females was CI: 8.59 versus 8.06, LI: 6.59 versus 6.13 and CA: 7.64 versus 07.15. The mean coronal tooth length (mm) of males versus females was CI: 10.19 versus 9.39, LI: 8.70 versus 7.79 and CA: 10.06 versus 8.89. All width and length measures were significantly greater for males than for females. The mean coronal tooth width/length ratios for males versus females was CI: 0.85 versus 0.86, LI: 0.76 versus 0.79 and CA: 0.77 versus 0.81. A comparison between genders of the width/length ratios of the CI and LI were found not to differ, however the CA ratio for females was significantly greater than for males. A statistically significant difference was found to exist between the mean (cm) SH for males versus females: 181.2 versus 164.0. A positive correlation (p < or = 0.0001 to 0.0691) was found to exist between tooth group width/height ratios within genders. No significant correlation was found between any of the tooth dimensions or tooth group ratios and SH. The results of this study indicate that within male and female Caucasians, the mean width/length ratio of the maxillary 3 anterior tooth groups is 0.81. As well, within both genders there is a positive correlation between tooth group width/length ratios. The significance of these findings with respect to periodontal mucogingival plastic surgical procedures is discussed.

Adult↗
PubMed1998

A neuropsychological study of panic disorder: negative findings.

BACKGROUND: Gray (1982) proposed that the septo-hippocampal system, which plays an important role in learning and memory, may partially mediate anxiety. Thus, patients with anxiety disorders may manifest neurocognitive performance deficits. We hypothesized that patients with panic disorder would demonstrate learning and memory deficits relative to normal comparison subjects. METHOD: Comprehensive neuropsychological batteries were administered to 69 panic disorder subjects and 19 normal volunteers. RESULTS: There were no significant group differences in any neuropsychological performance domain including learning, memory, attention, visuospatial functioning, and psychomotor speed. Multiple regression conducted to evaluate the contribution of clinical symptoms to neuropsychological impairment within the panic disorder sample revealed that anxiety severity did not affect neuropsychological test performance. LIMITATIONS: Most patients had mild or moderate, rather than severe, panic disorder. CONCLUSION: Neuropsychological dysfunction was not associated with panic disorder.

Adolescent↗
PubMed1998

Potential of limited day 21 post-chemotherapy CT scan in predicting need for post-chemotherapy surgery in nonseminomatous testicular germ cell cancer.

UNLABELLED: Nonseminomatous germ cell cancers (NSGCC) have a varied response to chemotherapy, some melting away with resultant cure, some have tumour stem cell necrosis and residual benign disease whilst others are resistant to treatment. The latter two require surgical excision in order to identify those needing high intensity chemotherapy. OBJECTIVE: The aim of this study was to investigate whether it was possible to give an earlier prediction of need for surgery after chemotherapy on the basis of a limited CT scan performed after the first course. MATERIALS AND METHODS: Twenty-three patients with metastatic NSGCC undergoing induction chemotherapy were studied. The site of the maximum disease was noted before treatment and only this area was rescanned at day 21. The change in disease bulk, measured as maximum transverse diameter (MTD), was compared with appearances on a CT scan immediately after chemotherapy and post-treatment response. RESULTS: Of those patients showing a poor response on the day 21 scan (i.e. no change, or less than 50% reduction in MTD), 70% required early surgical excision of residual disease, while none of the good responders (i.e. greater than 50% reduction in MTD), required immediate surgery (p < 0.001). CONCLUSION: It is concluded that a limited day 21 CT scan may represent an independent predictor of good and poor response to chemotherapy, thus enabling reduction in chemotherapy and its toxicity in good responders and early identification of those who may need surgical excision, thereby permitting easier scheduling of these often difficult surgical procedures.

Adult↗
PubMed1998

Maturation of cell-substratum focal adhesions induced by depolymerization of microtubules is mediated by increased cortical tension.

Dynamics of alterations of focal adhesions (FA) induced by a microtubule-depolymerizing drug, colcemid, was examined in several types of fibroblastic cells. Evolution of individual FA in cultured cells was monitored by interference-reflection microscopy (IRM); at the end of the monitoring period (3 hours) the cells were fixed and immunofluorescence microscopy of the same FA was performed with an antibody against vinculin. Control and colcemid-treated cells remained non-motile and did not show lamellipodial activity at the edges. During the incubation, formation of new FA or disappearance of pre-existing FA did not occur in either colcemid-treated or control cultures. However, FA in colcemid-treated cells significantly increased in size in the course of a 3 hour incubation. The growth of FA was centripetal and sometimes was accompanied by the fusion of several adjacent FA. Immunofluorescence examination showed that colcemid-induced growth of FA was accompanied by accumulation of several proteins specific for these structures including vinculin, talin, paxillin and pp125FAK kinase. Immunoblotting with anti-vinculin antibody showed that incubation with colcemid considerably increased the amount of vinculin associated with the ventral membranes due to its partial redistribution from a soluble pool into the growing adhesions. A substantial increase in tyrosine phosphorylation of pp125FAK was also observed in colcemid-treated cells. In cells plated on elastic silicone rubber films, colcemid induced formation of wrinkles in the films and these wrinkles relaxed after treatment with cytochalasin D. These results confirm that microtubule depolymerization increases traction transmitted to the substratum by the actin cortex and shows that an increase in cortical tension accompanies maturation of FA. Taken together, these data show that short-term incubation with colcemid does not affect the formation of initial FA. In contrast, microtubule depolymerization considerably stimulates the maturation FA, manifested by their centripetal growth. Maturation is proposed to be mediated by increased cortical tension, which is caused by microtubule depolymerization.

Animals↗
PubMed1996

Automated system for the on-line monitoring of powder blending processes using near-infrared spectroscopy. Part I. System development and control.

An automated system for the on-line monitoring of powder blending processes is described. The system employs near-infrared (NIR) spectroscopy using fibre-optics and a graphical user interface (GUI) developed in the LabVIEW environment. The complete supervisory control and data analysis (SCADA) software controls blender and spectrophotometer operation and performs statistical spectral data analysis in real time. A data analysis routine using standard deviation is described to demonstrate an approach to the real-time determination of blend homogeneity.

Chemistry, Pharmaceutical↗
PubMed1996

Imaging the traction stresses exerted by locomoting cells with the elastic substratum method.

The cytoskeletal activity of motile or adherent cells is frequently seen to induce detectable displacements of sufficiently compliant substrata. The physics of this phenomenon is discussed in terms of the classical theory of small-strain, plane-stress elasticity. The main results of such analysis is a transform expressing the displacement field of the elastic substrate as an integral over the traction field. The existence of this transform is used to derive a Bayesian method for converting noisy measurements of substratum displacement into "images" of the actual traction forces exerted by adherent or locomoting cells. Finally, the Monte Carlo validation of the statistical method is discussed, some new rheological studies of films are presented, and a practical application is given.

Animals↗
PubMed1995

Traction forces in locomoting cells.

A means of determining quantitative maps of the tractions exerted by locomoting cells on a substratum has been developed. This method is similar to the Harris silicone substratum assay [Harris et al., 1980: Science 208:177-179], but uses an improved non-wrinkling film that deforms more predictably in response to traction forces. The method also utilizes a mathematical analysis of rubber deformation to produce the final map of the distribution of tractions. The resulting maps consistently showed that fish keratocytes exert a steady-state "pinching" on the substratum, perpendicular to the cell's direction of locomotion. No significant rearward tractions were detected at or near the front edge of the cell. Likewise, no significant forward tractions associated with peeling of adhesions were found at the back of the cell. A second assay uses deflection of a lightly attached glass microneedle to measure the total force exerted by locomoting cells. Forces of approximately 4.5 x 10(-3) dyn were required to "stall" locomoting keratocytes. The implications of these findings for cell movement are discussed.

Animals↗
PubMed1994

Forces exerted by locomoting cells.

The movement of cells along substrata is a complex phenomenon involving cell extension and retraction, and cell-substratum adhesion. Knowledge is beginning to accumulate about the forces required for cell protrusion and retraction. Both of these processes also require traction to be exerted on the substratum, and new assays for these forces are under development. This review briefly discusses the forces that locomotory cells exert, in terms of both recent force measurements and possible mechanisms for their generation.

Actins↗
PubMed1994

Traction forces generated by locomoting keratocytes.

Traction forces produced by moving fibroblasts have been observed as distortions in flexible substrata including wrinkling of thin, silicone rubber films. Traction forces generated by fibroblast lamellae were thought to represent the forces required to move the cell forwards. However, traction forces could not be detected with faster moving cell types such as leukocytes and growth cones (Harris, A. K., D. Stopak, and P. Wild. 1981. Nature (Lond.). 290:249-251). We have developed a new assay in which traction forces produced by rapidly locomoting fish keratocytes can be detected by the two-dimensional displacements of small beads embedded in the plane of an elastic substratum. Traction forces were not detected at the rapidly extending front edge of the cell. Instead the largest traction forces were exerted perpendicular to the left and right cell margins. The maximum traction forces exerted by keratocytes were estimated to be approximately 2 x 10(-8) N. The pattern of traction forces can be related to the locomotion of a single keratocyte in terms of lamellar contractility and area of close cell-substratum contact.

Animals↗
PubMed1993

Subcutaneous recombinant interleukin-2 and alpha-interferon in patients with advanced renal cell carcinoma: results of a multicenter Phase II Study.

A phase II multiinstitutional clinical trial was conducted to evaluate the safety and efficacy of the subcutaneous outpatient administration of recombinant human interleukin-2 and alpha-interferon in patients with progressive metastatic renal cell carcinoma. One hundred and forty-five patients were entered on this study between October 1989 and May 1991. Among 134 patients evaluable for treatment response, there were six complete (4.5%) and twenty partial (14.9%) responders, with an overall response rate of 19.4% (95% confidence interval, 13-26%). The median duration of complete remissions was 228 (range 51(+)-520+) days; the median duration of partial tumor regressions was calculated at 226 (range 112-473+) days. The overall median survival from start of therapy was 14.2 (range 1-23+) months. Fever, chills and general fatigue occurred in the majority of patients treated and were measured at grade II, III and IV in up to 55%, 24% and 3% of all evaluable patients, respectively. Three patients each developed grade III hypotension, dyspnea and diarrhea; two patients each had grade III and grade IV elevations of alkaline phosphatase; two and one patients respectively, exhibited grade III anemia and grade IV thrombocytopenia; two patients experienced severe cutaneous toxicity. The majority of patients received treatment in the outpatient setting. In summary, the outpatient use of subcutaneous interleukin-2 and alpha-interferon was effective in patients with advanced metastatic renal cell carcinoma; it was associated with less toxicity and thus, could improve the therapeutic index of interleukin-2 based biologic therapy when compared against high dose intravenous therapy.

Adult↗
PubMed1993

Testicular cancer.

Despite the overall cure rate now in excess of 90%, innovation in management of germ cell tumors continues. The report that 80% of patients with extragonadal germ cell tumors have either carcinoma in situ or atrophic tubules as evidence of tumor rejection emphasizes the need to investigate the testis in patients with undiagnosed primary cancer because even today treatment delay is worsening prognosis. The evidence that testicular atrophy is a precursor of malignancy may explain why testis cancer has increased while normal sperm count has fallen over the past 50 years and why there is an association between exposure during service in Vietnam to agents that damage spermatogenesis and development of testis cancer. The improved prognostication from analysis of large databases and salvage with high-dose chemotherapy and bone marrow rescue are giving confidence to explore new innovations, eg, carboplatin instead of cisplatin. In addition, as the database on patients with stage I disease on surveillance enlarges, so does interest in adjuvant chemotherapy, encouraging the search for better markers to predict poor response. Linkage between overproduction of the tumor marker lactate dehydrogenase-1 and the increased copy number of the isochrome 12p in the tumor may be of use in this respect. Reports that germ cell tumor patients exposed to etoposide, eg, leukemic, lung, and ovarian cancer patients, can develop an acute myeloid leukemia with a marker on chromosome 11 are tempering enthusiasm for its use in adjuvant therapy. However, the observation that radiotherapy or chemotherapy may reduce second testis tumor incidence more effectively than surgery does encourages more detailed exploration of the results of adjuvant treatment.

Dysgerminoma↗
PubMed1991

Effect of organic anions on the crystallization of the Ca2(+)-ATPase of muscle sarcoplasmic reticulum.

The effect of varying the solute species on the crystallization of the Ca2(+)-ATPase from rabbit muscle reticulum (SR) is reported. We have found that substitution of KCl with salts of organic acids in the crystallization protocol reported by Pikula et al. has a profound effect on the size of two-dimensional crystalline arrays. Crystalline arrays of up to 3 microns diameter have been obtained by incubating purified calcium ATPase in standard crystallization medium but with 0.8 M sodium propionate substituted for KCl. These two-dimensional (2-D) arrays display a reduced tendency to stack in addition to having larger planar dimensions. Increasing the KCl concentration does not have the same effect on stacking or crystal growth that sodium propionate has. The production of 2-D sheets has some dependence on the hydrocarbon chain length of the salt because crystals formed in propionate were larger and less stacked than those formed in acetate or formate. There seems to be no dependence on cation. These observations suggest that in addition to reducing the forces that lead to stacking of the sheets, propionate may facilitate incorporation of the detergent-solubilized protein into the 2-D sheet.

Acetates↗
PubMed1990

GDA-J/F3 monoclonal antibody as a novel probe for the human sperm tail fibrous sheath and its anomalies.

GDA-J/F3 monoclonal antibody (MoAb) recognized an antigen in the fibrous sheath (FS) of human spermatozoa. This was based on: (i) intracellular localization of the antigen which was limited to the principal piece of the sperm tail; (ii) its absence from the cilia of trachea and nasal mucosa which lack FS; (iii) immunogold electron microscopy (IEM) which confirmed its ultrastructural localization to the FS. The antibody was used for the detection of abnormal germ cells in human semen. Nucleated cells other than spermatozoa (NCOS) obtained from oligozoospermic donors were screened with GDA-J/F3 MoAb using the indirect immunofluorescence test. The antibody which stains only the tails in normal cells, produced diffuse cytoplasmic immunofluorescence inside some spermatids. Using phase contrast microscopy, the tails in these spermatids were either present or undetectable. Electron microscopy studies of the NCOS showed the lack of the FS in those which had the tails (afibrous tail), or the presence of disorganized tails (tail dysgenesis) in the others. This antibody therefore provides a useful analytical tool for probing the FS as well as for the easy identification of certain abnormal germ cells in human semen.

Antibodies, Monoclonal↗
PubMed1989

Speech understanding in the elderly.

Both auditory and cognitive status were determined in 130 elderly persons, in the age range from 51 to 91 years. Data were analyzed from the standpoint of the congruence of auditory and cognitive deficits. The prevalence of central auditory processing disorder was 50%, and the prevalence of cognitive deficit was 41%. Findings in the two areas were congruent, however, in only 63% of the total sample. Central auditory status was abnormal in the presence of normal cognitive function in 23% of subjects. Central auditory status was normal in the presence of cognitive deficit in 14% of subjects. In general, results did not support the hypothesis that decline in speech understanding in the elderly can be explained as the consequence of concomitant cognitive decline.

Aged↗
PubMed1987

Interaction of age and intersignal interval on acoustic reflex amplitude.

We studied the effect of intersignal interval (ISI) on the averaged acoustic reflex in nine young and nine elderly subjects. Over the range of ISIs from 1.5 to 9 sec, there was an interaction between ISI and age group, but the effect was unique to reflex mode. Results emphasize the importance of measuring both crossed and uncrossed reflex waveforms, in the study of aging, and of controlling the ISI in order to avoid overestimation of aging effects.

Acoustic Impedance Tests↗