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Biomedical subjects

P Lott

Publications and source records attributed to P Lott.

8 recordsLinked to original sources
PubMed2003

Cellular mechanism of thymic involution.

Involution of the thymus and alterations in the development of thymocytes are the most prominent features of age-related immune senescence. We have carried out a comparative analysis of thymocyte and stroma in rapid thymic involution DBA/2 (D2) strain of mice compared with slow involution C57BL/6 (B6) strain of mice. Analysis of mice at 15 months of age suggested an age-related decrease in the thymocyte cell count, a block in the development of T cells and cortical involution in D2 mice compared with 3-month-old mice. TUNEL (terminal-deoxynucleotidyl-transferase-mediated dUTP-digoxigenin nick end labelling) staining and fluorescence-activated cell sorter (FACS) analysis showed that there was a significant increase in apoptotic cells in the cortex region of thymus in 15-month-old D2 mice compared with the same aged B6 mice. The thymocyte proliferation rate, as assessed by bromodeoxyuridine (BrdU) staining and [3H]-thymidine incorporation assay, was lower in 3-month-old D2 mice compared with the same age B6 mice. Immunohistochemical staining showed that the arrangement of MTS (mouse thymus stromal)-10+ epithelial cells and MTS-16+ connective tissue staining pattern had become disorganized in 15-month-old D2 mice but remained intact in B6 mice of the same age. These results suggest that, in D2 mice, both the thymocytes and stromal cells exhibit age-related defects, and that the genetic background of mice plays an important role in determining age-related alterations in thymic involution.

Aging↗
PubMed2003

Quantification of tartrate resistant acid phosphatase distribution in mouse tibiae using image analysis.

Tartrate resistant acid phosphatase (TRAP) activity of bone is a suitable biochemical marker for osteoclastic bone resorption. Qualitatively, the histochemical distribution of TRAP has been used to identify osteoclasts responsible for bone resorption; however, there have been few attempts to quantify TRAP localization. We describe a method for evaluating bone resorption by quantifying area percentages of positive TRAP localization using image analysis. Mouse tibiae were paraffin embedded following demineralization in disodium ethylenediamine tetraacetic acid. Longitudinal sections of tibia were cut from 15 levels in the left and the right limbs of six mice (180 sections total) and stained for TRAP distribution. Positive TRAP localization was quantified by pixel area count and reported as a percentage of the total tissue area specified. The 1.85 mm2 region of interest was placed at the midpoint of the epiphyseal growth plate containing the provisional calcification layer and the primary spongiosa, while excluding cortical bone of each mouse tibia. The percentage of TRAP localization ranged from 0.95 to 1.31% and was not significantly different from level to level or limb to limb in each mouse (p > 0.100). Within the same region of interest, an osteoclast count along the bone perimeter also was performed. We demonstrated a strong correlation (r2 = 0.903) between the conventional histomorphometric osteoclast index and positive TRAP localization, validating the latter as an alternative method to assess bone resorption. Quantitative analysis of TRAP is significant because it allows statistical comparisons between treatment groups, promotes precise pathological diagnoses and facilitates a reference data base that may aid the study of bone related diseases involving increased bone resorption.

Acid Phosphatase↗
PubMed2001

Effect of medroxyprogesterone pretreatment on pentagastrin-induced panic symptoms in females with panic disorder.

Clinical observation, as well as epidemiological and research data, suggest that female gonadal hormones influence the course of panic disorder (PD). Panicogenic agents such as pentagastrin are useful tools with which to study the pathophysiology of panic attacks. Nine women with PD were randomly assigned to receive, in a crossover design, a 3-day pretreatment with medroxyprogesterone acetate (MP) prior to an injection of pentagastrin, and a 3-day pretreatment with a placebo prior to another injection of pentagastrin. The panic response and the anxiety response to pentagastrin were decreased after MP pretreatment. These preliminary results support the use of laboratory models for investigations of the interactions between progestins and anxiety.

Adult↗
PubMed2000

Response to flumazenil in women with premenstrual dysphoric disorder.

OBJECTIVE: The authors sought to determine whether the administration of flumazenil would induce marked panic symptoms in women suffering from premenstrual dysphoric disorder. METHOD: Ten women with premenstrual dysphoric disorder and 11 comparison subjects were injected with flumazenil or placebo in a double-blind, randomized, balanced crossover design in a single session in the luteal phase of their menstrual cycles. RESULTS: Flumazenil induced a much greater panic response in the women with premenstrual dysphoric disorder than in the comparison subjects. CONCLUSIONS: These preliminary results are consistent with a dysregulation of the g-aminobutyric acid A/benzodiazepine receptor complex during the premenstruum of women suffering from premenstrual dysphoric disorder.

Cross-Over Studies↗