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Biomedical subjects

V Tangpricha

Publications and source records attributed to V Tangpricha.

6 recordsLinked to original sources
PubMed2005

Colon cancer and solar ultraviolet B radiation and prevention and treatment of colon cancer in mice with vitamin D and its Gemini analogs.

It has been recognized that people who live at higher latitudes and who are vitamin D deficient are at higher risk of dying from many common cancers including colon cancer. To evaluate the role of vitamin D deficiency on colon tumor growth, Balb/c adult male mice were fed either a vitamin D sufficient or vitamin D deficient diet for 10 weeks. Mice were arranged into groups of six and each animal received subcutaneously 10(4) MC-26 cells in the posterior trunk. The tumor size was recorded daily. By day 9 there was a significant difference in tumor volume between the vitamin D sufficient and vitamin D deficient mice. By day 18 the vitamin D deficient animals had a tumor size that was 56% larger compared to the animals that were vitamin D sufficient. To determine whether treatment with active vitamin D analogs could further decrease colon tumor growth in a vitamin D sufficient state, groups of mice were treated with the novel 19-nor-Gemini compounds. The mice were fed a low calcium diet. Twenty-four hours after tumor implantation, the mice received, three times weekly, one of the vitamin D analogs or the vehicle. The group that received Gemini 1,25-dihydroxy-21(3-hydroxy-3-trifluoromethyl-4-trifluoro-butynyl)-19-nor-20S-cholecalciferol (3) showed a dose-dependent decrease in tumor volume. On day 19, at the dose level of 0.02microg molar equivalents (E), the tumor volume was reduced by 41% when compared to the control group. At the same time point, the hexadeuterated analog 1,25-dihydroxy-21(3-hydroxy-3-trifluoromethyl-4-trifluoro-butynyl)-26,27-hexadeutero-19-nor-20S-cholecalciferol (4), administered at the 10-fold lower dose of 0.002microgE, showed a 52% reduction in tumor volume (p<0.05), compared to the control group. Animals that received 1,25(OH)(2)D(3) at 0.002 and 0.02microg showed a trend in tumor volume reduction at the highest dose but the changes were not statistically significant. An evaluation of serum calcium concentrations revealed that the calcium levels were normal in all groups, except the group receiving 0.02microgE of 4. The results from these studies demonstrate that vitamin D deficiency may accelerate colon cancer growth and that novel Gemini analogs of 1,25(OH)(2)D(3) may be an effective new approach for colon cancer treatment.

Animals↗
PubMed2001

25-hydroxyvitamin D-1alpha-hydroxylase in normal and malignant colon tissue.

Vitamin D affects calcium metabolism and prevents proliferation of colon cells in vitro. In human beings the main circulating form of vitamin D is 25-hydroxyvitamin D; to regulate calcium homoeostasis, this form must be converted to 1alpha, 25-dihydroxyvitamin D by 1alpha-hydroxylation in the kidney with 25-hydroxyvitamin D-1alpha-hydroxylase. Cultured transformed colon cancer cells can convert 25-hydroxyvitamin D(3) to 1alpha,25-dihydroxyvitamin D(3). We identified messenger RNA (mRNA) for 25-hydroxyvitamin D-1alpha-hydroxylase in normal colon tissue and in malignant and adjacent normal colon tissue. These findings support the notion that vitamin D might have a role in cell growth regulation and cancer protection, and might be the explanation for why the risk of dying from colorectal cancer is highest in areas with the least amount of sunlight.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2001

Twenty-one-gauge needles provide more cellular samples than twenty-five-gauge needles in fine-needle aspiration biopsy of the thyroid but may not provide increased diagnostic accuracy.

The technique of fine-needle aspiration (FNA) biopsy of the thyroid is important to evaluate malignancy in thyroid nodules. Eighty-five percent of thyroid FNA procedures lead to sufficient cellular material for diagnosis. With more cells aspirated, the chance of sufficiency for diagnosis increases. Large-bore needles lead to more cellular material being aspirated but bloodier specimens that may interfere with cytologic interpretation. Small-bore needles may result in too few cells for diagnosis. We conducted a randomized prospective study contrasting 21-gauge and 25-gauge needles in the evaluation of 50 consecutively enrolled nodules at our institution. In our investigation, 21-gauge needles more frequently provided superior biopsy specimens (50%) than did 25-gauge needles (18%). In the remaining specimens (32%), the 21-gauge and 25-gauge needles provided similar cellular material. The rate of sufficient samples was the same. We conclude that use of 21-gauge needles results in more cellular specimens but may not result in increased diagnostic accuracy.

Biopsy, Needle↗
PubMedDate not supplied

Compliance with guidelines for thyroid nodule evaluation.

OBJECTIVE: To determine whether guidelines recommended by the American Association of Clinical Endocrinologists (AACE) for assessment of a solitary thyroid nodule have been applied in clinical practice. METHODS: We retrospectively examined the pattern of testing in patients with solitary thyroid nodules at our institution during a 2-year period. We also attempted to determine whether consultation with an endocrinologist affected the workup. Patients who underwent a thyroid scan, ultrasonography, fine-needle aspiration (FNA) biopsy, or a thyroid surgical procedure for investigation of a solitary thyroid nodule between Jan. 1, 1996, and Dec. 31, 1997, were included in the study. Test results were reviewed for these patients. Patients were categorized into two groups, those with and those without a consultation with an endocrinologist. RESULTS: Inclusion criteria were met by 89 patients, 65% of whom had an FNA biopsy in their evaluation (the sole test in only 9%). A thyroid scan was done in 90% of patients, and an ultrasound study was done in 25%. Patients seen by an endocrinologist were more likely to undergo FNA biopsy than those who were not (82% versus 29%; P<0.001). Many patients who underwent assessment because of solitary nodules had normal findings on thyroid scans (21% of scans). CONCLUSION: The AACE guidelines for evaluation of thyroid nodules have not yet been fully implemented. Although a third of all study patients with a solitary thyroid nodule did not have an FNA biopsy, endocrine referral increased the rate of performance of this procedure. Thyroid scans seem to be overutilized; the high number with normal findings suggests that nuclear imaging studies are done to confirm physical findings. Early referral to an endocrinologist may be a more cost-effective workup of a possible thyroid nodule.

Journal Article↗
PubMedDate not supplied

Vitamin D and cancer.

The correlation between decreased morbidity and mortality of cancer and exposure to sunlight is known. The many biological functions of vitamin D that contribute to cancer prevention have only recently begun to be appreciated. Once activated 1,25-dihydroxyvitamin D [1,25(OH)2D3] functions as a potent inhibitor of normal and cancer cellular proliferation. Vitamin D deficiency in mice led to a 60% increase in colon tumor growth, compared to vitamin D-sufficient mice. The ligand binding domain of the Vitamin D receptor was shown to accommodate a class of 1,25(OH)2D3-analogs that possess an additional side-arm. These novel Gemini analogs were evaluated in vitro and in vivo. Select Gemini analogs were 100 times or more effective in inhibiting colon tumor growth in mice, compared to their parent compound. Correcting vitamin D deficiency may decrease the risk of developing colon cancer, while the novel Gemini 1,25(OH)2D3-analogs have the potential for therapeutic application in human colon cancer.

Animals↗