Temperature resistance was measured in goldfish which had been maintained under controlled photoperiods during different seasons over a twelve month period. A consistently higher heat resistance was found in fish which had been kept under the longer photoperiod. The cold resistance of short-day fish was greater than that of long-day fish in the fall and winter, but in the spring and summer the relationship seemed to be reversed. Thyroid uptake of radioiodine was determined in fish which had been subjected to the same photoperiod treatment. Short-day fish showed a consistently higher uptake of I¹³¹ , although the differences were not statistically significant. Photoperiodically adapted fish treated with thyroxine or TSH showed increased resistance to cold. Thiouracil caused the reverse effect, but thiourea caused increased resistance in the long-day group. Tissue cholesterol analyses were carried out on fish treated with thyroid materials. Gonad weight/body weight relationships were compared in fish maintained under the two photoperiods to determine possible correlations between the state of sexual maturity and thermal resistance. / Science, Faculty of / Zoology, Department of / Graduate

Changes in serum protein-bound iodine (PBI) levels were estimated in pregnant and non-pregnant mature ewes during the months from August to March. The PBI levels in ewes appeared to be elevated by low temperature (P < 0.001) and depressed by high temperature. The estrous cycle affected the PBI levels in ewes. The peak of PBI level was within 48 hours of estrus period. Breed differences played an important part on PBI levels; the Dorset breed generally had a higher PBI level than the Suffolk crossbred animal. The PBI levels in pregnant ewes became significantly higher (P < 0.05) than in the control after the third week of pregnancy. This increase in PBI level was followed by a significant increase (P < 0.05) in body weight gain at the seventh week of pregnancy. Toward the end of pregnancy (last seven weeks) the ewes with twin lambs had a significantly higher PBI level than the ewes with single lambs. The higher PBI levels remain elevated after parturition until the end of the lactation period. The PBI levels of lambs implanted with 3 and 6 mg diethystilbestroi (DES) were determined. Female lambs had a higher PBI level than mature ewes. Ten days after DES implantation, a significant (P < 0.001) increase in PBI levels was observed. This was followed by an increase in body weight gain over the control of 35% and 37% for 3 and 6 mg DES implants respectively during the remaining part of the experiment. There was a difference in the response to DES treatment between sexes. The wethers grew faster than the female lambs; this difference in growth rate can be reduced by treating the ewes with a larger dose of DES. Iodinated casein (protamone trade name, 1% thyroid activity) fed at 0, 0.25, 0.5 and 1 gm and also in combination with 1.75 mg DES were fed daily to growing lambs. The results showed that Protamone feeding to lambs as well as in combination with DES, caused a significant increase in PBI levels over the controls (P < 0.001). Blood glucose measurements showed a parallel with PBI in fluctuation. The blood sugar levels of lambs were found to be higher than those of mature ewes. DES and Protamone feeding caused an increase rate of gain over the control (DES 13.2 lb; 0.25 gm Protamone 8.7 lb)and improved feed efficiency (DES 1:3.4; Protamone 1:3.9 and control 1:5.6). / Land and Food Systems, Faculty of / Graduate

This dissertation is submitted as a final copy as the University’s Academic and Clinical supervisor / Background Thyroid gland involvement in advanced laryngeal malignancies is a rare entity, mostly resulting from direct contiguous spread from anterior and inferior tumours. Reported practice is to perform a hemithyroidectomy at the time of laryngectomy. However, this results in pointless excision of functional tissue and the added morbidity of hypothyroidism post operatively. Aim The aim of this study is twofold: firstly, to assess the frequency of thyroid gland involvement in laryngectomy specimens from Chris Hani Baragwanath Hospital, and secondly, to determine any association between the anatomical subsites of tumour and thyroid gland involvement. Methods This is a retrospective clinical audit of histological reports on laryngectomy specimens collected over a 10 year period from January 2005 and December 2014. The study was conducted at Chris Hani Baragwanath Hospital, affiliated to the University of the Witwatersrand, in South Africa. ENT operating registries and the laboratory database were used to access all records of total laryngectomies done over the 10 year period. Seventy-three laryngectomies were done, 9 were excluded as no thyroid tissue was included in the sample and 1 was excluded due to inadequate demographic detail. Thus a total of 63 histological reports were included in the study. Data extracted included age, race, sex, pathological stage of tumour, thyroid gland involvement and anatomical subsites involved by tumour (subglottis, anterior commissure and transglottic tumours). Data was analysed using standard statistical methods including a Fischer-exact test and an ANOVA association test. Statistica software was used. Results Four of the 63 cases had thyroid gland involvement (6.35%). The majority of the patients were black males in the age group 50 to 60 years of age. The tumours were all advanced laryngeal malignancies and only 2 of the 63 cases were found to have a diagnosis of adenosquamous carcinoma and chondrosarcoma. None of the anatomical subsites were found to be statistically significant in association with thyroid gland involvement, however, this result was thought to be skewed due to the small number of tumours involving the thyroid gland. Conclusion In accordance with South African and international studies on the same topic, thyroid gland involvement in laryngeal tumours is a rare occurrence. Due to the complications of performing a thyroidectomy and the hypothyroidism that accompanies it, a thyroidectomy should not always be performed. However, due to the recurrence rates and poor prognosis of patients with stomal recurrence (associated with thyroid gland involvement), thyroidectomy still needs to be considered. Based on known anatomical pathways of extralaryngeal spread of tumours via the anterior commissure, paraglottic spaces and those tumours involving the subglottis, selected patients require thyroidectomy at the time of laryngectomy to achieve adequate oncological margins. / MT2017

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published_or_final_version / abstract / Surgery / Master / Master of Philosophy

published_or_final_version / abstract / Surgery / Master / Master of Surgery

Thesis--University of Göteborg. / Includes bibliographical references (p. 26-29).