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Biomedical subjects

W C Baker

Publications and source records attributed to W C Baker.

11 recordsLinked to original sources
PubMed1993

Evaluation of the chick wing territory as an equipotential self-differentiating system.

Harrison (1918: J. Exp. Zool. 25: 413-461) described a developmental field as an "equipotential self-differentiating system." The present study was undertaken to address the question: To what extent can be pre-limb territory of a chick embryo be considered a developmental field? To what extent is the chick pre-limb territory an equipotential self-differentiating system? Two sets of experiments were undertaken to address these questions: (1) Whole and half limb territories were explanted to the celoma of host embryos, and (2) portions of the wing territories were extirpated. The wing exhibited the quality of self-differentiation after stage 12, in that the isolated wing territory, grafted to a host celom, could form limbs beginning at stage 12 (however, complete wings formed only from wing territories of stage 16 and older). On the other hand, the chick wing territory did not appear to exhibit equipotentiality. No posterior half limb graft formed normal limbs, and only in two exceptional cases did anterior half limb grafts form limbs. If part or all of the wing territory was removed from chick embryos, normal limbs formed in less than 15% of the cases after stage 15, in about 30% of the cases at stages 13 and 14, but in over half the cases at stages 10-12. Wound healing and reinitiation of limb potential may be responsible for the higher incidence of limb formation at the younger ages.

Animals↗
PubMed1990

Loss of root length and crestal bone height before and during treatment in adolescent and adult orthodontic patients.

It is broadly documented that orthodontic tooth movement enhances the risk of apical root resorption and loss of alveolar crestal bone height, but virtually all studies have focused on the conventional adolescent patient. In this study, samples from adolescent and adult patients were matched for sex, malocclusion, and treatment regimen. In-treatment changes in root length were the same for both groups, whereas loss of crestal bone height was somewhat greater in adults. Major differences, however, were found at the start of treatment: Adults (mean = 28 years) had significantly shorter roots and greater alveolar recession than the young teenagers (mean = 12 years). Consequently, treatment per se does not place adults at greater risk; it is the involvement extant at the start of mechanotherapy that merits careful evaluation.

Adolescent↗
PubMed1988

Prostatic-specific antigen: clinical experience utilizing immunoperoxidase staining techniques in patients with metastatic prostate cancer.

A human prostatic-specific antigen was first purified in 1979 by M.C. Wang et al. In the years to follow, investigators have been able to develop antisera to prostatic-specific antigen. Using an immunoperoxidase technique to stain both fresh and archival specimens, tissue of prostatic origin can be identified. The stain in our experience has been both specific and sensitive as an indicator of extraprostatic spread of carcinoma. We describe five cases where this technique has been useful in clinical practice.

Aged↗
PubMed1988

Misleading testicular masses.

Benign intrascrotal neoplasms of the testicle account for less than 10 per cent of all intrascrotal masses in postpubertal males. Radical inguinal orchiectomy is standard treatment for a firm, intratesticular mass. Of those patients so treated, 93 per cent of patients with this finding will have had the appropriate operation. There are misleading conditions, however, that can cause firm lesions in the testicle. There is a controversy over whether or not our current technology preoperatively can detect these benign lesions accurately. We encountered five different benign testicular masses within a twelve-month period. We present our findings and comments on some of the difficulties in dealing with these.

Adolescent↗
PubMed1988

Characterization of urinary keratin number 18 using a new assay.

The levels of the low-molecular weight keratin 18 appearing in the voided urine of 130 healthy volunteers was studied using a new immunoradiometric assay for keratin 18 (IRMAK-18). Keratin 18 was detected in 79 urines with an average level of 2.5 +/- 4.7 ng./ml. The assay does not detect complex epidermal keratins or non-keratin intermediate filaments. Only 50% of the purified keratin added to urine could be recovered. The recovered keratin had the same molecular weight as the input molecules, implying that substances in the urine physically inhibited the assay rather than destroyed the keratin. The independent variables of cell count, dead cells, and protein concentration were not found to be important in evaluating the results. However, the urine concentration, as measured by creatinine, might be an important consideration for assessing the levels of keratin detected.

Adult↗
PubMed1988

Quantitative analysis of keratin 18 in the urine of patients with bladder cancer.

The level of urinary keratin was compared in patients with and without bladder cancer using the newly developed IRMAK-18. Patients with bladder cancer had higher levels of keratin (74.6 +/- 146.9) than normals (2.5 +/- 4.7). When the upper limit of normal was set at keratin less than 20 ng./ml., the test was highly specific (98%) for bladder cancer but had a sensitivity of only 46%. Adjusting to keratin less than 10 ng./ml. increased the sensitivity to 57% but decreased the specificity to 91%. Elevated keratins were associated with stage and grade, aneuploidy and disease history. The IRMAK-18 assay for keratin may be useful for monitoring the clinical progress of some patients.

Adult↗
PubMed1988

Pseudomyxoma peritonei presenting as a scrotal mass.

Pseudomyxoma peritonei may occur after intraperitoneal rupture of a mucinous adenocarcinoma. The liberated cells produce copious amounts of mucus, which mimics ascites. With the improved technology of computerized tomography and ultrasound, many of these cases are now being diagnosed preoperatively. Surgical debulking is the preferred therapy, while the role of chemotherapy and radiotherapy remains debatable. We report a case of pseudomyxoma peritonei presenting as a scrotal mass that was diagnosed preoperatively.

Adult↗
PubMed1988

Urine: a suitable sample for deoxyribonucleic acid flow cytometry studies in patients with bladder cancer.

Deoxyribonucleic acid flow cytometry of bladder washings has proved to be a valuable procedure for the diagnosis and followup of patients with transitional cell carcinoma. However, for this procedure to gain maximal acceptance, it should be possible to use voided urine specimens instead of bladder washings. To evaluate this possibility we compared histogram findings for 114 bladder washings and 122 concomitantly obtained urine samples (voided and catheterized) from 89 consecutive patients who had active or a history of transitional cell carcinoma. Unsatisfactory histograms were obtained in 4 per cent of the urine samples and in 2.6 per cent of the bladder washing samples. The satisfactory rate for voided or catheterized urine samples was the same. We conclude that in this patient population satisfactory deoxyribonucleic acid histograms can be obtained from samples of voided urine.

Carcinoma, Transitional Cell↗
PubMed1987

Superovulation and recovery of zygotes from Nubian and Alpine dairy goats.

Thirty-five purebred dairy goats (18 Alpines and 17 Nubians) were subjected to a superovulating hormone program consisting of an 11-d 6alpha-methyl-17alpha-acetoxy-progesterone; (MAP; 60 mg) intravaginal sponge treatment; 125 ug i.m. injections of the prostaglandin F(2alpha) analogue cloprostenol on d 1 and 9 of vaginal sponge treatment; and a 3-d, twice-a-day injection of 2.5 mg of pituitary follicle stimulating hormone (FSH-P) i.m. starting at day 9. Vaginal sponges were pulled the morning of day 11 at the time of the fifth FSH-P injection. Of 40 initiated superovulatory cycles, 33 does (10 Alpines and 23 Nubians) responded with an average of 17.7 (range 1 to 29) ovulations. There was no significant difference between the breeds with respect to corpora lutea (CLs) plus follicles ovarian response. A significantly greater (P< 0.05) number of Nubian does were in estrus and mated by 36 h after MAP sponge removal. All does that responded to treatment had done so within 72 h of sponge removal. Of the seven (17.5%) does that showed no estrous response to hormone treatment, six were Alpines (P < 0.01). Six goats (two Alpines and four Nubians) were subjected to a second hormone treatment cycle after a 45-d rest. Five of six does responded to a second hormone treatment cycle with four of five responding with a lower total ovarian response. The interval from sponge removal to mating did not affect the stage or quality of eggs harvested. Rather, the interval from mating to surgical flushing determined the stage of egg development. All animals examined from 24 to 32 h after initial mating had not ovulated. By 50 h, 20 of 22 does had ovulated. A total of 242 ovulated eggs (63%) was harvested, of which 199 (82%) were fertilized. Day 7 flushings yielded 36 eggs (67%), of which 28 (78%) were fertilized. This rate of superovulation, fertilization, and embryo recovery lends credibility to this technique in its ultimate objective of rapidly increasing the number of offspring from superior animals.

Journal Article↗
PubMed1976

The influence of duration of circulatory arrest at 20 degrees C on cerebral changes.

In infants and piglets subjected to periods of circulatory arrest at 20 degrees C there was close correlation between duration of arrest and delay in return of electroencephalographic activity. Post mortem studies demonstrated histological evidence of brain damage in patients after circulatory arrest at 20 degrees C. Similar histological changes were demonstrated in piglets, including some who had complete E.E.G. and clinical recovery from circulatory arrest.

Animals↗