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Biomedical subjects

K Nowels

Publications and source records attributed to K Nowels.

9 recordsLinked to original sources
PubMed2001

Ultrasonographically guided thyroid biopsy: a review with emphasis on technique.

We describe our technique for ultrasonographically guided fine-needle aspiration biopsy of the thyroid that achieves a high rate of diagnostic specimens. Indications for ultrasonographically guided fine-needle aspiration biopsy included a difficult-to-palpate thyroid nodule and previously unsuccessful palpation-guided fine-needle aspiration. Ultrasonographically guided fine-needle aspiration biopsy was performed on 316 thyroid nodules in 306 patients. Adequate cytologic specimens were obtained in 97.2% of the nodules in which biopsy was performed, with a 2.8% rate of inadequate cellularity. Two helpful aspects of this technique that were thought to improve the overall diagnostic yield were the use of color and power Doppler "vascular mapping" of the nodule just before biopsy and on-site cytologic control.

Biopsy, Needle↗
PubMed2001

Iodine and thyroid cancer risk among women in a multiethnic population: the Bay Area Thyroid Cancer Study.

Research on the relationship between iodine exposure and thyroid cancer risk is limited, and the findings are inconclusive. In most studies, fish/shellfish consumption has been used as a proxy measure of iodine exposure. The present study extends this research by quantifying dietary iodine exposure as well as incorporating a biomarker of long-term (1 year) exposure, i.e., from toenail clippings. This study is conducted in a multiethnic population with a wide variation in thyroid cancer incidence rates and substantial diversity in exposure. Women, ages 20-74, residing in the San Francisco Bay Area and diagnosed with thyroid cancer between 1995 and 1998 (1992-1998 for Asian women) were compared with women selected from the general population via random digit dialing. Interviews were conducted in six languages with 608 cases and 558 controls. The established risk factors for thyroid cancer were found to increase risk in this population: radiation to the head/neck [odds ratio (OR), 2.3; 95% confidence interval (CI), 0.97-5.5]; history of goiter/nodules (OR, 3.7; 95% CI, 2.5-5.6); and a family history of proliferative thyroid disease (OR, 2.5; 95% CI, 1.6-3.8). Contrary to our hypothesis, increased dietary iodine, most likely related to the use of multivitamin pills, was associated with a reduced risk of papillary thyroid cancer. This risk reduction was observed in "low-risk" women (i.e., women without any of the three established risk factors noted above; OR, 0.53; 95% CI, 0.33-0.85) but not in "high-risk" women, among whom a slight elevation in risk was seen (OR, 1.4; 95% CI, 0.56-3.4). However, no association with risk was observed in either group when the biomarker of exposure was evaluated. In addition, no ethnic differences in risk were observed. The authors conclude that iodine exposure appears to have, at most, a weak effect on the risk of papillary thyroid cancer.

Adult↗
PubMed1988

Prostate specific antigen and acid phosphatase-reactive cells in cystitis cystica and glandularis.

Cystitis cystica (CC) and cystitis glandularis (CG) are common in the urothelium lining the bladder neck and trigone. Because some cases of CG show histologic features strikingly similar to prostatic acini, we hypothesized that some such foci may represent prostatelike metaplasia in the urinary bladder. Forty surgical and autopsy bladder specimens (23 males, 17 females) showing CC or CG were studied using anti-prostate specific antigen and anti-prostate specific acid phosphatase antibodies. Fourteen (35%) of these 40 cases showed positive staining for prostate specific antigen or prostate specific acid phosphatase or both in CC or CG foci. Among these were five female patients. The findings indicate that bladder epithelium is capable of undergoing prostatelike metaplasia and lend support to the hypothesis that the adult bladder stroma closest to the prostate may exert inductive influences on the overlying epithelium to show prostatelike metaplasia.

Acid Phosphatase↗
PubMed1986

Effects of formalin-induced injuries on urinary bladder carcinogenesis.

In multistage carcinogenesis, promotion is a long-term or repeated growth stimulation of initiated cells. Possible effects of regenerative hyperplasia induced by repeated intravesical instillation of 0.3% formalin solution on urinary bladder carcinogenesis were examined using heterotopically transplanted rat urinary bladders (HTBs) initiated by N-methyl-N-nitrosourea. The HTB system was chosen because in this system, transient generalized hyperplasia lasting less than a week can be induced readily and repeatedly by intravesical instillation of the formalin solution. No statistically significant tumor enhancement was observed after 15 formalin treatments administered in 30 weeks. It appears that regenerative cytotoxic stimuli, even multiple, may have no significant tumor-promoting activity. Discussed is the possibility that mild and, more importantly, persistent non-cytotoxic stimuli may be more effective as tumor promoters.

Animals↗
PubMed1986

Cytological atypia in the prostate gland: frequency, distribution and possible relevance to carcinoma.

Frequency and distribution of atypical prostatic hyperplasia were assessed in 51 total prostatectomy specimens for cancer and the data were compared to similar data obtained from analysis of 51 autopsy specimens. Enlargement of columnar cell nuclei in conjunction with preservation of basal cells was chosen as the only criterion for atypia. Depending on the degree of nuclear enlargement, atypia was divided into mild and severe degrees. The evaluation of nuclear atypia was applied to areas of carcinoma as well as to atypical prostatic hyperplasia. There were 3 major findings. 1) Atypical prostatic hyperplasia was found more frequently in prostatectomy specimens (48 of 51 cases) than in autopsy specimens (14 of 37 cases after exclusion of cancer-associated cases) and the difference was significant (p less than 0.001). In addition, atypical prostatic hyperplasia found in prostatectomy specimens was more frequently of severe degree than that in the autopsy specimens (42 of 48 versus 3 of 14 cases, p less than 0.001). 2) The distribution of atypical prostatic hyperplasia and carcinoma in prostatectomy specimens was similar. 3) In a majority of prostatectomy specimens atypical prostatic hyperplasia, when found, was located at sites separate from carcinoma as well as in contiguous areas. Based on these data it is suggested that the presence of a severe degree of nuclear atypia in specimens removed for benign conditions or in prostatic needle biopsies may signify an increased incidence of coexisting carcinoma elsewhere in the prostate or of carcinoma developing in the future. Close followup of these patients may be indicated.

Aged↗
PubMed1986

Prevention of inhibitory effects of alpha-difluoromethylornithine on rat urinary bladder carcinogenesis by exogenous putrescine.

We previously demonstrated that repeated instillation of alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), inhibits (or retards) urinary bladder carcinogenesis in rats. Since ODC catalyzes the first step in polyamine synthesis, the inhibition of polyamine formation may be responsible for tumor inhibition by DFMO. The present experiment was conducted using male Fischer rats with a heterotopically transplanted urinary bladder (HTB) to determine whether the effects of DFMO are prevented by exogeneous Pu. HTBs were treated with 0.25 mg of N-methyl-N-nitrosourea (MNU) once a week for 3 weeks and the animals were then arbitrarily divided into 6 groups. Beginning one week following the last MNU treatment, all rats received twice a week instillation (0.5 ml each) as follows: Group 1 rats, normal rat urine; Group 2, 2% DFMO in urine; Group 3, 250 microM Pu and 2% DFMO in urine; Group 4, 250 microM Pu in urine; Group 5, urine for 10 weeks followed by 2% DFMO in urine; and Group 6, urine for 10 weeks followed by 250 microM Pu and 2% DFMO in urine. At 10 weeks following the last MNU instillation 5 rats from each of Groups 1 through 4 were killed for determination of urothelial polyamine levels. An additional 4 rats of Group 1 were killed at 10 weeks for histological examination. All remaining rats were killed 20 weeks after the last MNU instillation. Polyamine levels showed no significant difference among the 4 groups. The incidence of carcinoma was significantly lower in the group treated with DFMO (p less than 0.001, Group 1 vs Group 2), confirming our previous observation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Nongestational choriocarcinoma in the postpartum period: a case report.

PURPOSE: To determine the tissue of origin (gestational versus nongestational) of an extensive metastatic choriocarcinoma in an 18-year-old woman to determine prognosis and treatment. METHODS: DNA microsatellite polymorphisms after polymerase chain reaction (PCR) amplification of the tumor tissue and blood from the patient, husband, and daughter were used to determine the tissue of origin. RESULTS: Molecular analyses revealed that the tumor shared the genetic features of only the patient. She responded well to multiagent chemotherapy. CONCLUSIONS: Molecular analysis is a useful tool to determine whether a choriocarcinoma occurring in a female patient of child-bearing age is gestational or nongestational when clinical findings are not clearly indicative of the primary.

Adolescent↗