Showing papers by "University of Queensland published in 1974"

An Electron-Microscope Study of Cell Deletion in the Anuran Tadpole Tail During Spontaneous Metamorphosis with Special Reference to Apoptosis of Striated Muscle Fibres

Abstract: The mechanism of cell deletion responsible for involution of the anuran tadpole tail during spontaneous metamorphosis was studied by light and electron microscopy, attention being focused on epidermis and striated muscle. The earliest indication of pending dissolution of epidermal cells was found to be aggregation of condensed chromatin beneath the nuclear envelope. This is followed by breaking up of the nucleus, and cytoplasmic condensation and budding with the production of a number of compact, membrane-bounded cell fragments with relatively well preserved organelles. These are then ingested and degraded by nearby viable cells, the majority by distinctive macrophage-like cells, which are scattered throughout the epidermis, and a few by epithelial cells. The morphological changes observed in the dying epidermal cells are the same as those described both in the ‘programmed cell death’ that plays an important role in the normal development of vertebrate embryos and in the type of cell death that has been shown to be involved in regulating the size of tissues in adult mammals under normal as well as pathological conditions; it has been suggested elsewhere that apoptosis might be a suitable name for the phenomenon. Deletion of striated muscle fibres in the tadpole tail is accomplished by a process that appears to be a modification of classical apoptosis, in which dilatation and confluence of elements of the sarcoplasmic reticulum lead to internal fragmentation, the usual surface budding presumably being precluded by the large volume and specialized structure of these cells. The early and late nuclear changes, and the apparent ultrastructural integrity of organelles in the membrane-bounded muscle fragments are typical of apoptosis, and subsequent degradation within macrophages follows the standard stereotyped pattern. An essentially similar process has been described by others in the muscles of metamorphosing insect larvae, but whether striated muscle cells in adult higher vertebrates can undergo apoptosis is still uncertain.

Plasma protein binding of diphenylhydantoin. Effects of sex hormones, renal and hepatic disease.

Abstract: The in vitro binding of diphenylhydantoin (DPH) to the protein in plasma from 97 volunteers has been studied using ultrafiltration at 37° C. The capacity of plasma protein to bind DPH did not differ significantly between pregnant women (11.6 ± 1.7% of total drug unbound), women taking oral contraceptives (9.9 ± 1.7% unbound), healthy males (10.6 ± 1.3% unbound), and healthy females (11.0 ± 3.2% unbound). However, in plasma from patients with renal disease (15.8 ± 3.9% unbound), hepatic disease (15.9 ∥ 6.0%) or hepatorenal disease (15.6 ± 5.4%), the protein binding of DPH was significantly decreased. These changes in protein binding were found to correlate better with changes in albumin and bilirubin levels in plasma than with any o f 13 other biochemical parameters examined.

Cell-Mediated Immunity and Specific Serum Factors in Human Cancer: The Leukocyte Adherence Inhibition Test

Abstract: Blood leukocytes from patients with cancer (malignant melanoma; adenocarcinoma of colon, rectum, and breast) reacted with aqueous extracts of tumors of the corresponding type, with the result that adherence of the leu kocytes to glass was diminished. Leukocytes from normal individuals did not react. The leukocyte adherence inhibition (LAI) test could be completed in a few hours. Sera from tumor-bearing patients blocked the LAI reaction of their own leukocytes or leukocytes from other patients with the same type of tumor. Serum blocking activity was lost soon after surgical removal of the tumor; the patient’s serum then became unblocking. The LAI technique gave consistent results in a series of patients, analogous to those reported with the lymphocyte cytotoxicity test, and was easier and quicker.

Studies on the immunity of sheep to Oesophagostomum columbianum: effects of low-protein diet on resistance to infection and cellular reactions in the gut.

Abstract: Adult Oesophagostomum columbianum populations were larger in sheep fed low-protein diets than in adequately fed animals. Diet did not influence the numbers of larva which became established in sheep. Sheep fed high-protein diets eliminated more worms and were more immunologically competent than poorly fed animals. More encapsulated larvae, showing arrested development, were found in adequately fed sheep than in those fed low-protein diets. Adult O. columbianum produced eggs at an earlier time after infection in poorly fed sheep than worms in well fed sheep. More eggs/female worm were produced in sheep on a low-protein diet compared with the number of eggs produced in well fed hosts over the last week of the infection. The effects of immunity on the behaviour of the worm in both host diet groups is discussed.There was a greater cellular proliferation in the intestines of infected adequately fed sheep than in infected animals on low-protein diets. These changes were most pronounced in the large intestine where the adult parasites were found. The macrophage-lymphocyte series of cells underwent hyperplasia in well fed animals but these changes were reduced, particularly among the plasma cells, in sheep fed low-protein diets. Increased mucin and mast cell counts were observed in sheep on high-protein, but not in hosts on low-protein diets: the intestinal populations of eosinophil and globule leucocytes were also reduced in poorly fed sheep.The relationship of these various cellular reactions and their effect on the protective immunity of sheep to O. columbianum is discussed. It was concluded that the increased susceptibility of protein deprived sheep to O. columbianum infections was associated with malfunctions of the innate immunity of the gut, involving decreased peristalsis and failure of the mucin cell response, and with reduction of the adaptive immune response which was reflected by impoverished lymphocyte and plasma cell reactions, and possibly with poor cooperation between sensitized lymphocytes, antibodies and the mast cell-granulocyte effector mechanisms in protective immunity.

Potency and selectivity in vitro of compounds related to isoprenaline and orciprenaline on β-adrenoceptors in the guinea-pig

Abstract: 1 Amines related in structure to either isoprenaline (catechol series) or orciprenaline (resorcinol series) were examined for activity on isolated trachea (relaxation), atria (chronotropic action) and perfused hind-limb (vasodilatation) of the guinea-pig. 2 Compounds with a resorcinol nucleus were less potent on all three preparations but more selective for trachea than were compounds with a catechol nucleus. 3 In both catechol and resorcinol compounds potency on trachea was enhanced by and selectivity for trachea was favoured by substitution of a p-OH phenyl group in the N-iso propyl, or by replacement of the N-iso propyl with an N-t-butyl, with or without a p-OH phenyl group. 4 Most of the compounds, particularly the resorcinols, had much lower potencies, relative to isoprenaline, on hind-limb than on trachea. 5 Some of the problems associated with the quantitative measurement of selectivity and with sub-classification of β-adrenoceptors are discussed.

Carbon‐13 assignments in 1‐ and 2‐naphthyl compounds: Extensive benefits of deuterium substitution

Abstract: The natural abundance, proton-decoupled carbon-13 spectra of 1-methylnaphthalene, 1-fluoronaphthalene, l-naphthonitrile and their 4-deutero analogues, as well as 2-naphthol and its 6-deutero analogue, have been recorded. Careful comparisons of the spectra of the deuterated and undeuterated compounds allow assignment, not only of the deuterated carbon, but also of the two ortho carbons (based on an upfield ‘two-bond’ deuterium isotope effect), as well as the two meta carbons (based on a significant J(CCCD) of ∼1 Hz) which causes substantial broadening). In the 1-naphthyl compounds, significant coupling between the deuterium (at C4) and C5 allows assignment of this latter carbon. Thus, the consequences of the introduction of one deuterium atom, together with results from off-resonance noise decoupling, permits assignment of most of the spectra. Tentative, but very likely assignments of the few remaining signals, can be made on the bases of chemical shifts and compressional effects. This approach could allow indirect assignment of an aryl carbon to which direct attachment of deuterium is difficult, due to directive effects of an existing substituent.

The epidemiology of dental occlusion: a critical appraisal

Abstract: The Editor was glad to publish this review of the literature because Dr. Jago appears to have performed quite a service in bringing together the information now available on indexes of malocclusion. Copyright

Clay Diapirism and Overthrust Faulting

Abstract: The fluid-pressure hypothesis of overthrust faulting is extended in terms of stratigraphically controlled clay diapirism in the upper 2 or 3 km of a young, regressive marine sedimentary sequence. Such a sequence, with thick clay loaded by coarse clastic sediments, is mechanically unstable because the clay beds initially are undercompacted and have abnormal interstitial fluid pressures. This instability leads to clay diapirism in the form of narrow, rather steep anticlines separated by broad, gentle synclines. The anticlinal trends are roughly parallel to the margins of the sedimentary basin or to the depositional strike. If a slope is induced before the excess pressures dissipate, gravity sliding and overthrust faulting may take place. The direction of such slope will commonly be normal to the margin of the sedimentary basin or to the depositional strike. The maximum length of such thrust sheets (in the direction of transport) would be determined by the distance between diapiric anticlinal trends. The direction of overthrusting will normally be away from the orogen, in the direction of progradation of the regressive sequence.

Carcinoembryonic antigen by radioimmunoassay in the detection of recurrence during long-term followup of female genital cancer.

Abstract: In the study, radioimmunoassay for carcinoembryonic antigen (CEA) was used in 75 patients with female genital cancer, who were followed up on a long‐term basis. These patients were assessed for the following disease status at each visit: free of disease, residual disease, or recurrence of disease. They also had periodic determinations of CEA in serum performed independently. The majority of patients who remained free of disease showed a rapid disappearance of CEA after treatment, whereas those who had residual disease continued to show persistence of CEA in serum. The patients who developed recurrence showed a re‐appearance of CEA after its initial disappearance; the mean time interval between re‐appearance of CEA and detection of clinical recurrence was 10.7 weeks. The CEA assay is considered to be a useful aid to the assessment of subsequent behavior of the tumor after primary treatment.

Some problems concerning Knowledge in Plato's "Charmides"

Abstract: The following discussion is concerned mainly with the interpretation of four passages in the Charmides and no attempt is made at a full account of what is meant by 'knowledge of knowledge' (=7rL<0! ?zm6rp5)q or of how this might be related to the main theses of Socratic ethics. Nor is anything so bold intended as the elucidation of such philosophical questions as the dialogue deals with, but rather, with humbler aims and more restricted compass, the clarification of some obscure features of Plato's argument. The first passage deals with the formulation of the definition of temperance as knowledge of knowledge henceforward regularly called K.K., an abbreviation whose ugliness is perhaps less objectionable than the repetition of the full expression in Greek or English. Here, 165c-167a, I shall argue that there is not, as has often been stated and still more often implied, an illegitimate transition from 'knowledge of oneself' to 'knowledge of itself'. The difficulties here are resolved by reconstructing the proper order of steps in the transition and taking the major definition to be 'knowing what one knows or does not know'. The other passages are concerned with the utility of K.K., once this definition has been accepted for the purpose of the argument. At 169e I believe Plato has deceived himself into making the transition to 'knowledge of itself' which he, but not some interpreters, avoids at 165c-167a. The third passage is a mere detail, the meaning of -tpoac-drasnj'rau 170b, but only if this is understood can the force of Plato's argument be clearly seen. The fourth passage is the basic premise of Plato's argument that K.K. does not entail knowing what one knows, o'-rwov ?68e Lev C'MLarO0,u 'r68e 8' oux ma'rhn 170a. On this basis Plato argues that no bridge is possible between K.K. and a particular technique such as medicine. On the other hand he does envisage a limited utility for K.K. at 172b, thus allowing that a bridge of some sort is possible. This unacknowledged contradiction I explain with reference to the ambiguity of the basic expression 170a, for in 'of these things this one is knowledge, this one is not knowledge', the 'things' in question are unidentifiable

Nitrogen response and stocking rate of Pennisetum clandestinum pastures: I. Pasture nitrogen requirement and concentration, distribution of dry matter and botanical composition

Abstract: Ammonium nitrate was applied to a kikuyu (Pennisetum clandestinum) dominant pasture at annual rates of 0, 134, 336 and 672 kg N/ha. Each nitrogen (N) rate treatment was continuously grazed at three stocking rates (SR) designed to apply similar grazing pressures at each N level and covering a range from 2.2 to 16.6 Angus weaner cattle/ha. The N status of these pastures was periodically assessed 8-10 weeks after seasonal N applications by temporarily excluding stock and measuring d.m. and N response to additional ammonium nitrate application. Pasture growth response to additional N was constant and independent of SR and of annual N rate over the range 0 to 336 kg N/ha, despite wide variation in pasture availability. N concentration of plant shoots was increased by high SR and rate of N uptake was not significantly affected by SR. Pasture growth rate was positively related to annual N rate. Herbage yield of kikuyu leaf, stem and litter on offer, was negatively related to SR but weight of underground organs was unaffected. Increasing SR increased the proportion of leaf and the rate of tillering. Pasture availability was positively and linearly related to N rate from 0 to 336 kg N/ha and maximal at 336 kg N/ha; the size of the litter fractions and underground organs was generally independent of N rate. N % in leaf and stem was reduced at low SR; N % of leaf, stem, litter, rhizome and root was positively related to N rate which was more influential than SR. The effect of SR on the size and relative distribution of the N in plant tops and litter fraction is discussed. Kikuyu dominance was positively related to N rate and independent of SR. White clover invaded at N0 and N134 levels especially at a high SR.