OpenUCT :: Browsing by Department "Division of Physiological Sciences"

Browsing by Department "Division of Physiological Sciences"

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Open Access
A Histological method for the Biological estimation of Vitamin A
(1948) Coetzee, W H K
There are considerable differences between physico-chemical and biological results of Vitamin A estimations, owing to the fact that "the analyst determines the proportion of a substance present, whilst the bioassayist determines the effect"
Open Access
Changes in plasma inorganic phosphate associated with endocrine activity in Xenopus laevis
(1940) Schrire, Velva; Zwarenstein, H; Irving J T
The plasma inorganic phosphate level may be influenced by (1) factors affecting the intermediary metabolism of phosphorus, (2) alternation in the degree of absorption of phosphorus, (3) alteration in the degree of excretion of phosphorus. In the introduction, the intermediary metabolism of phosphorus, particularly as far as the endocrine glands are concerned, is discussed in detail, whereas the absorption and excretion are but briefly outlined.
Open Access
The effects of endurance training on lactate production and removal during progressive exercise in man
(1991) Macrae, Holden Steve-Henry; Noakes, Timothy D
It is a well-documented finding that blood lactate concentrations at any given absolute or relative (% of maximum oxygen uptake; % VO₂ₘₐₓ) workload, are lower following endurance training. The search for the mechanisms responsible for lower blood lactate concentrations after training, however, has led to conflicting results, particularly when the possible causes of this finding have been investigated in humans. In this study, three questions related to the effects of endurance training on lactate metabolism were investigated.
Open Access
The effects of pulsed static and oscillating magnetic fields on rat pineal serotonin N-acetyltransferase activity
(1997) Isaacs, Ian J; Beardwood, C J
Concerns about the possible hazardous effects of electromagnetic fields (EMF ' s) has resulted in attempts to address this issue. Several authors have shown that EMF exposure affects biological systems and more specifically the pineal enzyme, serotonin N-acetyltransferase (SNAT), inhibiting the enzyme and thus melatonin production. The enzyme assay required, for performing this type of work is crucial, as the natural decay of the enzyme could bias experimental results. An assay for measuring SNAT activity was assessed and then improved. The Ca²⁺ ion chelator, EGTA (2mM), preserved enzyme activity during pineal homogenisation. The enzyme is heat sensitive and thus keeping the homogenates on ice facilitated enzyme preservation. Not only was preservation of the enzyme crucial, but optimum substrate concentrations were required to measure maximum levels of SNAT activity. Maximum levels of activity were measured when I/10th of a pineal gland was incubated with 12mM tryptamine. At the specified tryptamine concentration, SNAT activity increased as the concentration of Acetyl CoA increased. The enzyme efficiency, as determined from its Km (8.19x10⁻⁴M), and the level of activity exceeded those measured in other laboratories. This assay was used to determine SNAT activity following magnetic field exposure. The magnetic field studies investigated the effects of pulsed static and oscillating magnetic fields on SNAT activity. Male Long Evans rats were housed in short and long photoperiods and were exposed for either 60mins., 30mins. or 15mins. to magnetic fields at different times during the dark phase. Rats were exposed to regularly repeated inversion of either the vertical or horizontal component of the earth' s magnetic field or to regularly repeated horizontal or vertical lOOμT DC field inversions. Pulsed static magnetic field exposure in all conditions had no significant inhibitory effect on SNAT activity. Oscillating magnetic field studies investigated the effect of exposure of rats to magnetic fields tuned to ion parametric resonance conditions for Ca²⁺. The ion parametric resonance model of Blanchard and Blackman was used to determine the exposure parameters. Rats were thus exposed for an hour to a vertical AC field, of strength 14.3μT (rms), frequency was 17.2Hz while the strength of the vertical DC field was 22.55μT, the existing vertical geomagnetic field strength. Under these conditions oscillating magnetic field exposure also had no significant inhibitory effect on SNAT activity.
Open Access
The Food Environment of Primary School Learners in a Low-to-Middle-Income Area in Cape Town, South Africa
(2021-06-15) O’Halloran, Siobhan A.; Eksteen, Gabriel; Polayya, Nadene; Ropertz, Megan; Senekal, Marjanne
Rapid changes in food environments, where less nutritious foods have become cheaper and more accessible, have led to the double burden of malnutrition (DBM). The role food environments have played in shaping the DBM has attained global interest. There is a paucity of food environment research in low-to-middle-income countries. We conducted a case study of the food environments of school aged learners. A primary school in Cape Town was recruited. A multi-method design was used: a home food and eating behaviours questionnaire completed by 102 household respondents and four questions completed by 152 learners; learner participatory photography; a semi-structured school principal interview; a tuckshop inventory; observation of three-day tuckshop purchases. Foods that were commonly present in households: refined carbohydrates, fats/oils, chicken, processed meats, vegetables, fruit, legumes, snacks/drinks. Two thirds of households had rules about unhealthy drinks/snacks, ate supper together and in front of the TV, ate a home cooked meal five–seven times/week and ate breakfast together under two times/week. Vegetables were eaten under two times/week in 45% of households. A majority of learners (84%) took a lunchbox to school. Twenty-five learners photographed their food environment and 15 participated in semi-structured interviews. Six themes emerged: where to buy; what is available in the home; meal composition; family dynamics; peer engagement; food preparation. Items bought at informal food outlets included snacks, drinks and grocery staples. The principal interview revealed the establishment of a healthy school food environment, including a vegetable garden, although unhealthy snacks were sold at the tuckshop. Key dimensions of the food environment that require further investigation in disadvantaged urban and informal settlement areas include the home availability of unhealthy foods, eating behaviours in households and healthfulness of foods sold by informal food outlets.
Open Access
Gravimetric studies of certain Amphibian Organs under normal and experimental conditions
(1939) Gitlin, Gershon
A cycle of seasonal ovarian weight changes in Xenopus is described, similar in all respects to that described by other workers.
Open Access
Histological and morphological studies of the endocrine organs of xenopus laevis
(1930) Rimer, Gladys E J
Xenopus Laevis has provided, during the last ten years, the basis of a growing body of physiological enquiries initiated by Jolly's research on reflex action. Its viability in the laboratory and amenability to operative procedure in particular, make it a peculiarly suitable object for investigation. It is regrettable therefore, that existing literature on the anatomy of Xenopus has been directed to elucidating those characteristics which are of especial interest to the Systematists and Morphologists rather than detailed information of a type which is essential to operative procedure. There is in particular no extant account of the endocrine system of Xenopus, although it is evident from superficial inspection that the suprarenal complex differs from that of the more familar Anura. The present enquiry concerns the Thyroid Gland, Pituitary and Epiphyseal Complexes with some observations concerning the possible occurrence of chromophil cells in the kidney of Xenopus laevis. The data have been placed on record specifically and constitution of these organs in physiological operations.
Open Access
Insulin: its assay, extraction and sources
(1950) Labuschagne, Christiaan Jacob Johan Troskie
In May 1992, Banting and Best, working in the Physiology Department of the University of Toronto, obtained the first active extracts from pancreas. The credit for the preparation of such extracts capable of effecting a lowering of the blood and urinary sugar, and serviceable in mitigating the symptoms of experimental diabetes in animals, and o human diabetes, therefore, belongs to these two workers, to Waoleod and Collip. Improvements in the methods of extraction and purification of insulin followed quickly. Accompanying this were the investigations of the physiological, chemical and physical properties of the hormone. Since that time a mass of evidence relating to the above and produce by a host of workers has accumulated.
Open Access
Intra-operative pneumatic tourniquet – perceptions of use and complications in the orthopaedic community of South Africa
(1996) Gibson, A St Clair; Lambert, M I; Milligan, J; Merwe, W van der; Walters, J; Noakes, T D
OBJECTIVES: To assess views on use, maintenance and side-effects of the pneumatic tourniquet in the South African orthopaedic community. METHODS: A census-type questionnaire study was conducted of all 475 orthopaedic surgeons registered with the Orthopaedic Association of South Africa during 1993/94. The chi-square test was used to determine statistical significance between different groups of respondents. RESULTS: Seventy-seven per cent of the questionnaires were returned. Ninety-nine per cent of respondents used a pneumatic tourniquet. Eighty-four per cent believed that the tourniquet may damage underlying tissue both as a result of applied pressure effects and ischaemic consequences. Fifty-four per cent of respondents personally checked the calibration of the pneumatic tourniquet, although 76% of respondents believe that the apparatus needs to be checked at least once per month. More respondents who did not check the tourniquet apparatus than respondents who did check it believe that applied pressure does not cause tissue damage (P < 0.001), that the operating room technician or hospital engineer should be responsible for checking equipment (P < 0.001), and that equipment did not need to be checked more than once every 6 months (P < 0.001). CONCLUSIONS: Although most orthopaedic surgeons are aware of the pneumatic tourniquet's side-effects, a minority appear to be unaware of the hazards of excessive applied pressure alone or excessive applied pressure caused by use of faulty equipment. It needs to be emphasised to these surgeons that regular checking of the pneumatic tourniquet apparatus is necessary in order to prevent postoperative complications ascribed to use of the tourniquet.
Open Access
Lipoids and blood platelets with reference to blood coagulation and the hemorrhagic diseases
(1956) Ferguson, John Howard
By specifically analysing for the various active principles of plasma, platelets, tissues and their fractions, much new information has been obtained concerning the role of lipoids and platelets in blood coagulation and in the hemostatic mechanisms in health and disease. Analysed components are studied in artificial clotting systems, especially a two-stage thrombin- forming system. Some 86 cases of bleeding disorders, 32 new born normal infants and their mothers, and many normal adult bloods have been analysed with respect to components of the clotting and hemostatic functions. The detailed considerations embodied in the thesis are encompassed under the following heads: 1) the importance of certain lipoids, especially cephalin 2) the normal need, in plasma clotting, for platelets, 3) the particular significance of a platelet component, which has many analogies to cephalin, in the thromboplastic system, 4) potentiation of the thromboplastic actions of cephalin, of platelets, and of tissue thromboplastin (to some extent) by a variety of experimental additives. Part of this may be explained as a 'thromboplastin generation' through co-participation of certain plasmatic components (antihemophilic globulin, PTC" etc. ) . Part, however, may be the result of certain proteolytic enzymes, particularly trypsin, 'disaggregating' lipoproteins and thus rendering their phospholipid (and sometimes calcium) available for participation in the clotting reactions, 5) possible Ca-containing and lipid-containing 'intermediates’ in the thrombin-forming reactions, 6) myelin figure formation as an explanation of ‘alterations' of platelets and certain other formed elements such as thrombocytes, megakaryocytes, and stromatolytic erythrocytes 7) the multiplicity of factors which platelets may contribute to the blood clotting and hemostatic mechanisms 8) the occurrence of many clinical disorders due to deficiency of platelet functions. Thrombocytopenias denote deficient numbers ('counts' and total bulk in body). Thrombocytopathies are deficiencies of specific platelet components, e . g. thromboplastic factor, accelerator, vasoconstrictor (5-hydroxy tryptamine), or retractor factor. Such deficiencies can be clinically significant even when the platelet count is normal. Bleeding in leukaemias, uremias, etc. may often be accounted for in these terms, 9) the nature and modes of action of heparin and other 'antithromboplastic’ inhibitors, and of some antiproteases, in relation to the mechanisms discussed 10) the ‘cephalin availability theory' of the author, as a useful working hypothesis to explain the importance of the natural thromboplastic phospholipid. Lipid release from platelet, tissue, or possibly plasma sources may very well be the long-obscure 'trigger mechanism' which initiates blood coagulation.
Open Access
Pituitary-gonadal control of creatinine metabolism.
(1937) Cheetham, Richard William Spencer
The endocrine in general for a considerable period have been known to exert a humoraal action on the body, controlling its functions to a large extent. These actions have been closely investigated and a clear correlation between the ductless glands have been shown. The interrelation and dependency of the one upon the other, either by inhibition or by stimulation, contribute towards the finer control of the physiology of the body. The studies recorded here are comprised mainly of the dependency of one gland upon another, the relation the normal gland has to protein metabolism, and the alteration in this protein metabolism brought about by alteration in the normal function of one or other of the ductless glands. These features are demonstrated by observing changes in the elimination of creatinine in urine, for this urinary creatinine is regarded as an index of endogenous protein metabolism, and the amount excreted is remarkably constant from day to day.
Open Access
Processing of transient stimuli by the visual system of the rat
(1993) Kara, Prakash; Douglas, Rodney J
While three decades of intensive cortical electrophysiology using a variety of sustained visual stimuli has made a significant contribution to many aspects of visual function, it has not supported the existence of intracortical circuit operations in cortical processing. This study investigated cortical processing by a comparison of the response of primary visual cortical neurones to transient electrical and strobe-flash stimulation. Experiments were performed on 74 anaesthetised Long Evans rats. Standard stereotaxic and extracellular electrophysiological techniques were employed. Continuous (on-line) raster plots and peri-stimulus time histograms (PSTHs) of the extracellular spikes from 81 visual cortical and 55 lateral geniculate nucleus (LGN) neurones were compiled. The strobe-flash stimuli (0.05 ms) were applied to the contralateral eye while the monopolar or bipolar electrical stimuli (0.2 ms, 80-400 μA) were applied to the ipsilateral LGN. 60 of the 81 (74%) tested cortical units were found to be responsive to visual stimuli. A distinct and consistent difference in the cortical response to the two types of transient stimuli was found: (a) Electrical stimulation evoked a prolonged period (197 ± 61 ms) of inhibition in all cortical neurones tested (n=20). This was the case even in those cortical units that were completely unresponsive to visual stimulation. The protracted inhibition was usually followed by a 100-200 ms phase of rebound excitation. (b) Flash stimulation evoked a prominent excitatory discharge (5-30 ms duration) after a latency of 30-60 ms from the onset of the stimulus (n = 59). This was followed by either moderate inhibition or return to a firing rate similar to control activity, for a maximum of 40 ms. Thereafter, cortical neurones showed a sustained increased level of activity with superimposed secondary excitatory phases. The duration of this late re-excitatory phase was 200-300 ms. In 17 of 20 (85%) tested units, the temporal profile of the cortical response to flash stimulation was modulated by small changes in the level of background illumination. In 16 of the 17 units, this sensitivity was reflected primarily as an emergence of a brief secondary inhibitory phase at the lowest level of background illumination (0 lux). Only 1 of the 17 cortical units displayed a flash-evoked primary inhibitory phase at O lux. We explored the possibility that neurones in the lateral geniculate nucleus (LGN) of the thalamus were responsible for the late phase of cortical reexcitation. 49 of the 55 (89%) LGN neurones could be classified as either of the "ON type" i.e. excited by visual stimuli, or the "OFF type" i.e. inhibited by visual stimuli. The response of ON-like LGN neurones to strobe-flash stimulation of the contralateral eye was characterised by a primary excitatory or early discharge (ED) phase after a latency of 25-40 ms. Thereafter, a 200- 400 ms period of inhibition was observed. In 57% of the sample, a rebound excitatory or late discharge (LD) phase completed the response. OFF-like LGN neurones were inhibited by the strobe-flash stimuli after a latency of 30- 35 ms. This flash-evoked inhibition was maintained for 200-400 ms. The sensitivity of the flash-evoked LGN response to the level of background illumination was tested in 11 ON-like and 10 OFF-like neurones. No sustained secondary excitatory events, as observed in visual cortical neurones, were found in any of the ON- and OFF-like LGN neurones, irrespective of the level of background illumination. In conclusion, the data show that the late re-excitatory phase evoked in cortical neurones upon strobe-flash stimulation, is not due to sustained LGN (thalamic) input. Rather, it suggests that these re-excitatory phases are due to intracortical processing of the transient stimuli. These findings emphasize the independent role of the cortex in computing the response to visual stimuli, and cast doubt on traditional theories that have emphasised the role of the thalamus in shaping cortical responses. The difference in the flash and electrically evoked cortical response suggests that even though substantial inhibition is available to the cortex, only a small fraction of this inhibitory capacity is utilised during natural stimulation.
Open Access
The regulation of postprandial lipemia in man
(1989) Cohen, Jonathan; Noakes, Timothy D; Benade, Spinnler
The regulation of the serum triglyceride responses to fat ingestion have been examined in normolipidemic men. To evaluate the existing methods for comparing chylomicron-triglyceride clearance, the oral and intravenous fat tolerance tests and a steady state duodenal perfusion method were compared. Good correlations (r > 0.8) were found between each of these methods. Since the intravenous fat tolerance test is independent of fat absorption, these data suggested that the serum triglyceride response to fat feeding was largely determined by the rate of chylomicron-triglyceride clearance. To determine the influence of the quantity and type of meal fat on postprandial serum triglyceride concentrations, the serum triglyceride responses to three different doses of dairy cream, and to standard doses of olive and sunflower oil were examined. For a given type of fat, the magnitude of postprandial lipemia (the integrated serum triglyceride excursion) varied directly with the quantity of fat in the meal. This finding suggested that the chylomicron- triglyceride clearance system(s) did not become saturated even after large fat meals. In addition, it appeared that the hormonal factors released in response to fat ingestion (some of which are known to increase lipoprotein lipase activity in vitro) did not increase the rate of chylomicron-triglyceride clearance. If the quantity of fat in a meal was fixed, then postprandial lipemia increased with increasing saturation of the triglyceride fatty acids. These differences did not appear to reflect differences in triglyceride absorption. Since acute fat feeding per se did not appear to stimulate chylomicron-triglyceride clearance, the effects of dietary proteins and carbohydrates were studied. The addition of up to 35g protein to a standard test meal did not affect postprandial lipemia. These results were supported by the observation that protein ingestion did not affect intravenous fat tolerance. Postprandial serum triglyceride concentrations were significantly influenced by carbohydrate ingestion. Fructose (50g) and sucrose (100g) markedly increased postprandial lipemia, although glucose ingestion did not. In agreement with earlier studies, glucose ingestion decreased serum triglyceride concentrations 2 hours after the meal. This effect was abolished by intraduodenal fat administration and by substituting starch for glucose in the test meal. The effects of glucose could be reproduced by iso-osmotic quantities of urea, however. These findings suggested that glucose ingestion did not increase chylomicron -triglyceride clearance. It is more likely that glucose delayed the absorption of triglycerides by slowing gastric emptying, and that this effect was partly related to the increased osmolarity of glucose- containing meals. The effects of chronic exercise on postprandial lipemia and chylomicron-triglyceride clearance were determined in endurance- adapted athletes. The serum triglyceride responses to large and small fat meals were lower in athletes than in sedentary men with comparable fasting triglyceride concentrations. These differences were not eliminated by a single bout of acute exercise in the sedentary men. The clearance of intravenously administered lntralipid, and chylomicron -triglyceride clearance assessed from steady state chylomicron-triglyceride concentrations during duodenal fat perfusion were faster in athletes than in the sedentary men. These data suggested that the low postprandial lipemia in athletes reflects increased chylomicron-triglyceride clearance caused by increased activity of the triglyceride clearing system(s). Given these considerations. it appears that the pathway(s) for chylomicron triglyceride clearance are extremely efficient in normal men and that these pathways are not subject to acute physiological regulation.
Open Access
Somatosensory processing by rat medial pontomedullary reticular formation neurones : responses to innocuous and noxious thermal and mechanical stimuli
(1991) Farham, Craig Jeffrey; Douglas, Rodney J
This work examines somatosensory processing in "giant" neurones of the medial pontomedullary reticular formation (PMRF) in the rat, with particular emphasis on the response to cutaneous thermal stimuli. Thermal test stimuli were employed as these were deemed to be more precisely quantifiable than other forms of cutaneous stimulation. Activity was recorded from 235 PMRF neurones in 94 female Long Evans rats (270 to 320 g) anaesthetised with urethane (1,25g/kg, i.p.). Rectal temperature was closely controlled at 38 ± 0,5°C. Standard stereotactic and extracellular recording techniques were employed. PMRF giant neurones were identified by their stereotactic location, large, stable spike amplitudes of long duration, responses to cutaneous mechanical stimuli and receptive field properties, and spontaneous discharge characteristics. Ramp, step and sine wave cutaneous thermal stimuli (35-48 °C) were applied to the glabrous skin on the hindpaw by means of a computer-controlled Peltier device. The location of the units was confirmed by subsequent histology. One hundred and eleven neurones were located in nucleus reticularis pontis caudalis (NPC), and 124 in nucleus reticularis gigantocellularis (NGC). Mechanical stimulation excited 188 of 235 (80%) PMRF neurones (ON-m cells), and inhibited 40 (17%, OFF-m cells). Seven cells (3%) had mosaic receptive fields of excitation and inhibition (complex responses, CX-m). Twenty-eight percent of neurones were responsive to both weak and intense stimuli (mixed neurones). The remainder (72%) responded only to intense mechanical stimulation of the skin (high threshold neurones). The (excitatory or inhibitory) response of the mixed neurones to intense stimuli was generally greater than to mild stimuli, Receptive fields ranged in size from restricted (hindlimbs only) to very extensive (covering the entire body surface). Neurones with small receptive fields were almost exclusively of the high threshold type, and tended to be located in NGC, while mixed neurones tended to have larger receptive fields, and were located predominantly in NPC. Some portion of the hind limbs were represented in the receptive fields of all but one of the neurones studied, while the tail and/ or trunk were represented in 77%, and the forelimbs and face in 28% of receptive fields. Most of the cells responding to cutaneous mechanical stimulation had bilateral (usually symmetric) receptive fields. Spontaneous (background) activity occurred in the absence of any deliberate sensory stimulation in 72% of PMRF neurones. The frequency of spontaneous discharge rates ranged from O to 47 spikes/ s. The coefficient of variation of the spontaneous discharge rate of a given neurone was generally less than 20% (range O to 85%). Of the 235 identified mechanosensitive PMRF neurones, 203 (86%) also responded to cutaneous thermal stimulation (43-48 °C) of the ipsilateral hind paw. Eighty percent of these responded with increased discharge rates (ON-t cells), and 20% were inhibited (OFF-t cells). The polarities of response of individual PMRF neurones to mechanical and thermal stimuli, and to repeated ipsilateral and contralateral thermal stimuli, did not differ significantly. Following transient thermal stimulation, spontaneous discharge rates largely returned to pre-stimulus levels. The thresholds of response to slow ramp (0,15°C/s) and stepped (2°C/s) thermal stimuli occurred both in the innocuous and noxious temperature ranges (below and above 42°C, respectively). The threshold temperatures showed large variability to repeated identical thermal stimuli. Despite the poor reproducibility of the threshold responses, the distribution of thresholds to thermal ramp stimuli was consistently bimodal, with peaks occurring at 39 and 43°C. The bimodality persisted even when the ipsilateral and contralateral data were pooled. The modes of these threshold distributions conform to the maximum discharge ranges for warm and noxious cutaneous receptors. Thus, it is likely that thermal input to individual PMRF neurones is derived from both types of receptors. The responses of PMRF neurones to repeated thermal stimuli were stable and reproducible with respect to magnitude and time course. The average (static) and maximum (dynamic) responses to thermal stimuli were generally small: for example, the mean of the average responses to ramp stimuli was 5,9 spikes/s ± 11,0 SD, (range -28 to 40 spikes/s), and the mean of the maximum responses was 9,3 spikes/s ± 16,1 SD, (range -46 to 65 spikes/s). The absolute change in firing rate of individual PMRF neurones, and of the population, increased monotonically as a function of the intensity of stepped cutaneous thermal stimuli in the range 40 to 48 °C. However, their resolution, based on their average and maximum responses, was poor. Incorporating the post-stimulus responses into the comparisons between different stimulus intensities marginally increased the resolution of these neurones. Thus, while the majority of PMRF neurones are able to distinguish innocuous from noxious stimuli, few are capable of encoding stimulus intensity within the noxious range (above 43 °C). The majority (70%) of PMRF neurones responded to sustained thermal stimuli with a slow increase or decrease to a new static discharge rate which was maintained with little or no adaptation. Latency to onset of response to stepped thermal stimuli varied from 1 to 50 seconds, and the time to maximal response between 5-60 seconds. Many PMRF neurones also showed marked after-discharge for periods of up to 5 minutes after removal of the stimulus. The thermal receptive fields of over 90% of PMRF neurones were large, incorporating at least both hindlimbs. The extensive receptive field sizes of individual PMRF neurones provides evidence against them having a role in stimulus location. The large number of PMRF neurones showing multimodal convergence, their small magnitude responses, their slow response times, and their large receptive fields strongly suggest that these neurones are not participating in classical sensory discrimination. Rather, they may function as stimulus detectors or alternatively play a role in associative processes.
Open Access
Splenic and portal venography
(1952) Dreyer, Barend Jansen van Rensburg; Irving, J T
In 1945 Blakemore and Lord published their work on the treatment of Banti's Syndrome by anastomosing the splenic to the left renal vein, or the portal vein to the inferior vena cava. In the same year Whipple (1945) classified portal hypertension into cases with an obstruction in the portal system outside the liver, and those with a block inside the liver, the result of hepatic fibrosis. The cases with extrahepatic blockage of the portal circulation present clinically as cases of Banti's Syndrome. In this latter group repeated haematemeses are a common, and often fatal symptom. The operation of portacaval anastomosis has as its main object the lowering of the pressure in the portal system, with a reduction in the frequency, and severity of the haematemeses. The operations are difficult and dangerous, and the patients suitable for operation must be selected carefully. The exact site of obstruction causing portal hypertension must be determined either at, or preferably before operation, as it will determine the type of operation. Thus an anastomosis between the portal vein and the inferior vena eava will be useless if haematemeses are the result of obstruction of the splenic vein.
Open Access
Studies in the biosynthesis of the hormones of the thyroid gland.
(1967) Wilson, Brian Denis; van Zyl, A.
This project was undertaken in order to elucidate two important problems in Thyroid Biochemistry namely, the kinetics of labelling of tyrosine and monoiodotyrosine (MIT) and the pathways of synthesis of triiodothyronine (T3 ) and thyroxine (T4 ).
Open Access
Studies in the physiology of creatine and creatinine
(1935) Shapiro, B G
The studies recorded in this thesis cover a wide portion of the field of creatine-creatinine metabolism. They involve a consideration of the problem of the origin of creatine, of the endocrine factors controlling its metabolism, and of the function of creatine and creatinine in the body. In order to obtain a true perspective of the place of these investigations in relation to the physiology of creatine as a whole, it is first necessary to review briefly what is known of the metabolism and function of the two substances. And, in view of the light they throw on these questions, consideration must also be given to the chemical constitution and distribution of creatine and creatinine.
Open Access
Studies in the reproductive Physiology of the Amphibia
(1939) Berk, Lionel; Forman, F
The changes occurring in the red blood cells in infective illness are amongst the least carefully studied problems of haematology. In spite of the fact that these anamias are extremely common, it is difficult to find adequate literature to make possible even a clear description of the blood picture under these circumstances. Part of the difficulty is due to the fact that anaemias in infections are grouped together with other anaemia, in which many mechanisms undoubtedly active. Another major source of confusion is the fact that in many of the cases in which "secondary anaemia" occurs, complicating factors such as haemorrhage and liver disease are not adequately dealt with.
Open Access
Studies in the reproductive Physiology of the Amphibia
(1939) Berk, Lionel; Forman, F
The changes occurring in the red blood cells in infective illness are amongst the least carefully studied problems of haematology. In spite of the fact that these anamias are extremely common, it is difficult to find adequate literature to make possible even a clear description of the blood picture under these circumstances. Part of the difficulty is due to the fact that anaemias in infections are grouped together with other anaemia, in which many mechanisms undoubtedly active. Another major source of confusion is the fact that in many of the cases in which "secondary anaemia" occurs, complicating factors such as haemorrhage and liver disease are not adequately dealt with.
Open Access
Tendon and Ligament Genetics: How Do They Contribute to Disease and Injury? A Narrative Review
(2022-04-29) Ribbans, William J; September, Alison V; Collins, Malcolm
A significant proportion of patients requiring musculoskeletal management present with tendon and ligament pathology. Our understanding of the intrinsic and extrinsic mechanisms that lead to such disabilities is increasing. However, the complexity underpinning these interactive multifactorial elements is still not fully characterised. Evidence highlighting the genetic components, either reducing or increasing susceptibility to injury, is increasing. This review examines the present understanding of the role genetic variations contribute to tendon and ligament injury risk. It examines the different elements of tendon and ligament structure and considers our knowledge of genetic influence on form, function, ability to withstand load, and undertake repair or regeneration. The role of epigenetic factors in modifying gene expression in these structures is also explored. It considers the challenges to interpreting present knowledge, the requirements, and likely pathways for future research, and whether such information has reached the point of clinical utility.

Browsing by Department "Division of Physiological Sciences"

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