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Biomedical subjects

Thomas Martin

Publications and source records attributed to Thomas Martin.

33 records · Page 2Linked to original sources
PubMed2004

Analgesic efficacy of orally administered buprenorphine in rats: methodologic considerations.

Buprenorphine has been widely recommended for treatment of pain in rodents. We have previously documented that the recommended postoperative oral dose of buprenorphine in male Long-Evans rats, 0.5 mg/kg, is not as effective as the recommended parenteral dose of buprenorphine (0.05 mg/kg, s.c.) as an analgesic. In the series of experiments reported here, we compared: the analgesic effect of buprenorphine when prepared in two ways in the laboratory with that of a commercially available injectable solution of buprenorphine; the analgesic effect of buprenorphine in Long-Evans rats with that in Sprague-Dawley rats; and Long-Evans and Sprague-Dawley rats for development of pica, a commonly reported side effect of buprenorphine. We followed the pica experiment with assessment of the effectiveness of buprenorphine in establishing a conditioned flavor aversion. The results indicated that method of preparation did not result in any significant differences in the efficacy of injected buprenorphine. Strain of rat was not associated with a significant difference in the efficacy of buprenorphine. However, a significant strain difference was found in development of pica. Buprenorphine treatment was effective in inducing a conditioned flavor aversion. We concluded that the recommended oral dose of buprenorphine (0.5 mg/kg) is ineffective as an analgesic, and that this was not the result of method of preparation of the buprenorphine or strain of rat used. Furthermore, we concluded that buprenorphine treatment may induce gastrointestinal distress in both strains tested. The results reaffirm our previous conclusion that oral administration of buprenorphine at 0.5 mg/kg, despite the general recommendation, is not a reasonable treatment for postsurgical pain in rats.

Administration, Oral↗
PubMed2004

An e-textile system for motion analysis.

Electronic textiles (e-textiles) offer the promise of home health care devices that integrate seamlessly into the wearer's everyday lifestyle while providing a higher level of functionality than current devices. Existing gait analysis systems are cumbersome laboratory-based systems that, while providing valuable information, would be difficult or impossible to deploy in the home. Yet gait analysis systems offer the promise of preventing and/or mitigating the serious effects of falls in the elderly population. This paper proposes an e-textile solution to this problem along with a design approach for realizing a solution that is inexpensive and usable across the elderly population. Preliminary results are given to demonstrate the promise of the proposed system.

Aged↗
PubMed2003

Chemically modified tetracyclines selectively inhibit IL-6 expression in osteoblasts by decreasing mRNA stability.

In bone biology, interleukin (IL)-6 is an autocrine/paracrine cytokine which can induce osteoclasts formation and activation to help mediate inflammatory bone destruction. Previous studies have shown that tetracycline and its derivatives have potentially beneficial therapeutic effects in the prevention and treatment of metabolic bone diseases by modulating osteoblast and osteoclast activities. Our previous studies indicated that non-antimicrobial chemically modified tetracyclines (CMTs) can dose-dependently inhibit IL-1 beta-induced IL-6 secretion in osteoblastic cells. In the present study, we explored the molecular mechanisms underlying the ability of doxycycline analogs CMT-8 and its non-chelating pyrazole derivative, CMT-5 to affect IL-6 gene expression in murine osteoblasts. Steady-state IL-6 mRNA was decreased with CMT-8 (ca. 50%) but not by CMT-5 when stimulated by IL-1 beta. CMT-8 regulation of IL-1 beta-induced IL-6 gene expression was further explored. CMT-8 did not affect IL-6 promoter activity in reporter gene assays. However, the IL-6 mRNA stability was decreased in the presence of CMT-8. These effects require de novo protein synthesis as they were inhibited by cycloheximide. Western blot analysis indicated that CMT-8 did not affect p38 mitogen-activated protein kinase, c-jun NH(2)-terminal kinases, or extracellular signal-regulated kinases (1 and 2) phosphorylation in response to IL-1 beta. These data suggest that CMT-8 can modulate inhibit IL-1 beta-induced IL-6 expression in MC3T3-E1 cells at the post-transcriptional level affecting IL-6 mRNA stability. These observations may offer a novel molecular basis for this treatment of metabolic bone diseases that are mediated by IL-6.

Animals↗
PubMed2003

HSP110-HER2/neu chaperone complex vaccine induces protective immunity against spontaneous mammary tumors in HER-2/neu transgenic mice.

Heat shock proteins (HSPs) are shown to be strong immunoadjuvants, eliciting both innate and adaptive immune responses against cancers. HSP110 is related in sequence to HSP70 and is approximately 4-fold more efficient in binding to and stabilizing denatured protein substrates compared with HSP70. In the present study we evaluated the ability of a heat shock complex of HSP110 with the intracellular domain (ICD) of human HER-2/neu to elicit effective antitumor immune responses and to inhibit spontaneous mammary tumors in FVB-neu (FVBN202) transgenic mice. The HSP110-ICD complex was capable of breaking tolerance against the rat neu protein and inhibiting spontaneous mammary tumor development. This vaccine induced ICD-specific IFN-gamma and IL-4 production. Depletion studies revealed that CD8(+) T cells were involved in protection against challenge with mouse mammary tumors, whereas CD4(+) T cells revealed partial protection. Increased IgG2a Ab titer in the sera of tumor-free animals after vaccination and elevated CD4(+) CD25(+) regulatory T cells in the PBL of tumor-bearing animals suggested that IFN-gamma-producing Th1 cells may be responsible for partial protection of CD4(+) T cells against the mammary tumor challenge, whereas CD4(+)CD25(+) regulatory T cells (Th2 cells) may suppress the antitumor immune responses. Together, these results suggest that HSP110-ICD complex can elicit effective IFN-gamma-producing T cells against spontaneous mammary tumors and that up-regulation of CD4(+) CD25(+) regulatory T cells may prevent complete eradication of the tumor following immunotherapy.

Animals↗
PubMed2003

Reduced-intensity conditioning for unrelated donor hematopoietic stem cell transplantation as treatment for myeloid malignancies in patients older than 55 years.

Hematopoietic stem cell transplantation from unrelated donors is an effective treatment for myeloid malignancies, but its use is usually restricted to young patients without comorbidities. The development of reduced-intensity preparative regimens has allowed the extension of this form of treatment to older and medically infirm patients. We assessed the outcomes of patients older than 54 years who received unrelated donor transplants for the treatment of myeloid malignancies in our institution. There were 29 patients (median age, 59 years) with advanced acute myeloid leukemia (n = 13), myelodysplastic syndrome (n = 7), and chronic myeloid leukemia (n = 9) included. With a median follow-up of 27 months, the probability of overall and event-free survival, and nonrelapse mortality at one year were 44%, 37%, and 55%, respectively. Grades II to IV acute graft-versus-host disease (GVHD) occurred in 41% of patients and chronic GVHD developed in 63% of patients surviving more than 100 days. Of the 11 survivors, 9 were interviewed and reported good quality of life after transplantation using the Functional Assessment of Cancer Therapy-Bone Marrow Transplant Scale (FACT-BMT) questionnaire, with high scores in all dimensions. Unrelated donor transplantation is a treatment option for older patients with myeloid malignancies. The results in this cohort of patients are comparable with those reported in younger patients with similarly advanced disease.

Age Factors↗
PubMed2003

Human kallikrein 2 (hK2) mRNA in peripheral blood of patients with thyroid cancer: a novel molecular marker?

PURPOSE: To elucidate whether hK2 mRNA can be detected in peripheral blood of patients with thyroid disease using reverse transcription polymerase chain reaction (RT-PCR). METHODS: A nested RT-PCR protocol for the detection of hK2 mRNA was established, and blood samples of 72 patients with a history of thyroid cancer, 10 patients with current metastases of thyroid cancer, and 32 volunteers were tested. RESULTS: hK2-transcripts were significantly more often detected in patients with thyroid cancer (20/72=28%) than in the control group (2/32=6%, P = 0.03, chi-square analysis). CONCLUSIONS: This is the first study reporting on hK2 as a potential molecular marker for patients with thyroid cancer. We could demonstrate a correlation between diagnosis of thyroid cancer and the positive signal for hK2 in the RT-PCR assay. Future studies are necessary to prove the clinical value of hK2 as a molecular marker regarding recurrence and outcome.

Adult↗
PubMed2003

Palliative interstitial HDR brachytherapy for recurrent rectal cancer. Implantation techniques and results.

PURPOSE: To report the methods and clinical results of CT-based interstitial high-dose-rate (HDR) brachytherapy procedures for the palliative treatment of recurrent rectal cancer. PATIENTS AND METHODS: A total of 44 brachytherapy implants were performed in 38 patients. CT-guided catheter implants were performed in 34 patients under local anesthesia and sedation, and four patients were implanted intraoperatively. Of 40 CT-guided implants, 20 were done using metallic needles introduced via the sacrum and 20 were transperineal implants of plastic tubes in the presacral region. Postimplant CT scans were used for three-dimensional (3-D) conformal brachytherapy planning. Patients implanted with metallic needles were given a single fraction of 10-15 Gy using HDR (192)Ir, and those who received transperineal implants of plastic catheters were given fractionated brachytherapy, 5 Gy twice daily to a total dose of 30-40 Gy. The median tumor volume was 225 cm(3) with a range of 41-2,103 cm(3). RESULTS: After a median follow-up of 23.4 months, a total of 13/38 patients were alive. The median postbrachytherapy survival was 15 months with 18 of the 25 deaths due to distant metastases. Tumor response was as follows: 6/38 partial remission, 28/38 stable disease, and 4/38 local progression. A planning target volume (PTV) coverage > 85% was achieved in 42/44 implants. The treatment was well tolerated, and no acute complications were observed. One patient developed a fistula after 8 months. Pain relief was recorded in 34 patients (89.5%), and the median duration of this palliative effect was 5 months with a range of 1-13 months. CONCLUSIONS: Interstitial HDR brachytherapy is a valuable tool for the delivery of high doses and achieves effective palliation in recurrent rectal carcinoma.

Aged↗
PubMed2003

Usefulness of tumor volumetry as a prognostic factor of survival in head and neck cancer.

BACKGROUND: The TNM classification system of tumor stage does not always reflect the actual tumor mass present at diagnosis. This study aimed at evaluating the prognostic value of volumetric data regarding survival in head and neck cancer patients being treated with either cisplatin or carboplatin administered concomitantly with radiotherapy. PATIENTS AND METHODS: We retrospectively analyzed 107 patients suffering from squamous cell carcinoma of the head and neck in a Greek-German cooperative study (see Table 1). All patients were treated by radiotherapy and concomitant chemotherapy. 65 patients received chemotherapy with carboplatin and 42 with cisplatin. More than 6,200 CT scans were analyzed by digitalization of contours which subsequently led to the computation of the tumor volume (primary and macroscopic lymph node metastases). RESULTS: Median follow-up was 43 months and median survival 30 months. Median initial tumor volume was 32.5 ml (range 2.1-220.1 ml) in the carboplatin and 44.4 ml (range 3.2-202.5 ml) in the cisplatin group (see Figure 1). After treatment, tumor volumes did not differ significantly (median of 3.1 ml [range 0.0-167.1 ml] and 3.5 ml [range 0.0-166.0 ml], respectively). 41 patients (63.1%) died in the carboplatin group and 22 patients (52.4%) in the cisplatin group (see Figure 2). Pretherapeutic tumor volume was prognostic with respect to survival while TNM classification and age were not. Pretherapeutic tumor volume was negatively and percent decrease in tumor volume positively associated with survival (see Tables 2 and 3). CONCLUSION: Knowledge of the initial tumor volume adds valuable information in terms of prognosis. Initial tumor volume should be included in all future clinical trials regarding head and neck cancer patients.

Adult↗
PubMed2003

Function and specificity of 14-3-3 proteins in the regulation of carbohydrate and nitrogen metabolism.

Protein phosphorylation is key to the regulation of many proteins. Altered protein activity often requires the interaction of the phosphorylated protein with a class of "adapters" known as 14-3-3 proteins. This review will cover aspects of 14-3-3 interaction with key proteins of carbon and nitrogen metabolism such as nitrate reductase, glutamine synthetase and sucrose-phosphate synthase. It will also address 14-3-3 involvement in signal transduction pathways with emphasis on the regulation of plant metabolism. To date, 14-3-3 proteins have been identified and studied in many diverse systems, yielding a plethora of data, requiring careful analysis and interpretation. Problems such as these are not uncommon when dealing with multigene families. The number of isoforms makes the question of redundancy versus specificity of 14-3-3 proteins a crucial one. This issue is discussed in relation to structure, function and expression of 14-3-3 proteins.

14-3-3 Proteins↗
PubMed2002

Remote sensing of oligotrophic waters: model divergence at low chlorophyll concentrations.

The performance of the OC2 Sea-viewing Wide Field-of-view Sensor (SeaWiFS) algorithm based on 490- and 555-nm water-leaving radiances at low chlorophyll contents is compared with those of semianalytical models and a Monte Carlo radiative transfer model. We introduce our model, which uses two particle phase functions and scattering coefficient parameterizations to achieve a backscattering ratio that varies with chlorophyll concentration. We discuss the various parameterizations and compare them with existent measurements. The SeaWiFS algorithm could be confirmed within an accuracy of 35% over a chlorophyll range from 0.1 to 1 mg m(-3), whereas for lower chlorophyll concentrations we found a significant overestimation of the OC2 algorithm.

Journal Article↗
PubMed2002

A Jurassic mammal from South America.

The Jurassic period is an important stage in early mammalian evolution, as it saw the first diversification of this group, leading to the stem lineages of monotremes and modern therian mammals. However, the fossil record of Jurassic mammals is extremely poor, particularly in the southern continents. Jurassic mammals from Gondwanaland are so far only known from Tanzania and Madagascar, and from trackway evidence from Argentina. Here we report a Jurassic mammal represented by a dentary, which is the first, to our knowledge, from South America. The tiny fossil from the Middle to Late Jurassic of Patagonia is a representative of the recently termed Australosphenida, a group of mammals from Gondwanaland that evolved tribosphenic molars convergently to the Northern Hemisphere Tribosphenida, and probably gave rise to the monotremes. Together with other mammalian evidence from the Southern Hemisphere, the discovery of this new mammal indicates that the Australosphenida had diversified and were widespread in Gondwanaland well before the end of the Jurassic, and that mammalian faunas from the Southern Hemisphere already showed a marked distinction from their northern counterparts by the Middle to Late Jurassic.

Animals↗
PubMed2002

Does prophylactic treatment with proteolytic enzymes reduce acute toxicity of adjuvant pelvic irradiation? Results of a double-blind randomized trial.

PURPOSE: Does prophylactic treatment with proteolytic enzymes reduce acute toxicity of adjuvant pelvic radiotherapy? MATERIAL AND METHODS: Fifty-six patients with an indication for adjuvant pelvic irradiation after curative surgery were double-blind randomized. All patients took 3 x 4 capsules study medication daily during radiotherapy. Twenty-eight patients in the enzyme group (EG) received capsules containing papain, trypsin and chymotrypsin, 28 in the placebo group (PG) received placebo capsules. All patients were irradiated with 5 x 1.8 Gy weekly to 50.4 Gy using four-field-box technique after CT-based planning. Primary objective was the grade of diarrhea, nausea, vomiting, fatigue and epitheliolysis during radiotherapy. Secondary objectives were the number of supportive medications and treatment interruptions due to acute toxicity. RESULTS: None/mild diarrhea: 43% EG, 64% PG. Moderate/severe diarrhea: 57% EG, 36% PG (P = 0.11). Mean duration: 11 days in EG, 10 days in PG. None/mild nausea: 93% EG, 93% PG. Moderate/severe nausea: 7% EG, 7% PG. None/mild vomiting: 100% EG, 97% PG. None/mild fatigue: 82% EG, 93% PG. Moderate/severe fatigue: 18% EG, 7% PG (P = 0.23). None/mild epitheliolysis: 75% EG, 93% PG. Moderate/severe epitheliolysis: 25% EG, 7% PG (P = 0.16). Treatment interruption (mean days): 2.44 in EG, 1.46 in PG. Number of supportive medication: 29 in EG, 19 in PG. CONCLUSIONS: The prophylactic use of proteolytic enzymes does not reduce acute toxicities, treatment interruptions and number of supportive medication and therefore does not improve tolerance of adjuvant pelvic radiotherapy.

Chymotrypsin↗
PubMed2002

Arabidopsis seedling growth, storage lipid mobilization, and photosynthetic gene expression are regulated by carbon:nitrogen availability.

The objective of the current work was to establish the degree to which the effects of carbon and nitrogen availability on Arabidopsis seedling growth and development are due to these nutrients acting independently or together. Growth of seedlings on low (0.1 mM) nitrogen results in a significant reduction of seedling and cotyledon size, fresh weight, chlorophyll, and anthocyanin content but a slight increase in endogenous sugars. The addition of 100 mM sucrose (Suc) to the nitrogen-depleted growth media results in a further reduction in cotyledon size and chlorophyll content and an overall increase in anthocyanins and endogenous sugars. Storage lipid breakdown is almost completely blocked in seedlings grown on low nitrogen and 100 mM Suc and is significantly inhibited when seedlings are grown on either low nitrogen or high Suc. Carbohydrate repression of photosynthetic gene expression can only be observed under low nitrogen conditions. Low (0.1 mM) nitrogen in the absence of exogenous carbohydrate results in a significant decrease in chlorophyll a/b-binding protein and ribulose bisphosphate carboxylase small subunit gene transcript levels. Thus, carbon to nitrogen ratio rather than carbohydrate status alone appears to play the predominant role in regulating various aspects of seedling growth including storage reserve mobilization and photosynthetic gene expression.

Anthocyanins↗
PubMed2002

Megestrol acetate stimulates weight gain and ventilation in underweight COPD patients.

STUDY OBJECTIVES: To assess the effect of megestrol acetate (MA), a progestational appetite stimulant commonly used in patients with AIDS and cancer, on body weight and composition, respiratory muscle strength, arterial blood gas levels, and subjective perceptions in COPD patients. DESIGN AND SETTING: Prospective, double-blind, randomized, placebo-controlled trial conducted on an outpatient basis at 18 sites. PATIENTS: Underweight (< 95% ideal body weight) COPD patients > or = 40 years old. INTERVENTIONS: Either MA, 800 mg/d oral suspension, or placebo at a 1:1 ratio for 8 weeks. RESULTS: Of 145 randomized patients (63% men), 128 patients completed the trial. Body weight increased by 3.2 kg in the MA group and 0.7 kg in the placebo group (p < 0.001). Anthropometric and dual-energy radiograph absorptiometry assessments confirmed that weight gain was mainly fat. Spirometry and maximal voluntary ventilation showed no significant changes from baseline in either group, and the difference in the change in maximum inspiratory pressure between groups was not significant. The 6-min walk distances did not differ statistically between groups at week 2 and week 4, but were greater in the placebo group at week 8 (p = 0.012). Consistent with the known ability of MA to stimulate ventilation, PaCO(2) decreased (4.6 mm Hg, p < 0.001) and PaO(2) increased (2.8 mm Hg, p < 0.04) in the MA group. Questionnaires revealed that body image and appetite improved in the MA group but not the placebo group. Adverse event frequency and type were similar in both groups, but cortisol and testosterone (in men) levels decreased substantially in the MA group. CONCLUSIONS: We conclude that MA safely increased appetite and body weight, stimulated ventilation, and improved body image in underweight COPD patients, but did not improve respiratory muscle function or exercise tolerance.

Aged↗