Biomedical subjects
Publications and source records attributed to D H Ellis.
Saksenaea vasiformis was identified as the causative agent in three cases of sub-cutaneous zygomycosis in Australia. The laboratory techniques for inducing clinical isolates of S. vasiformis to produce sporangia, necessary for the precise identification of the fungus, are described and compared.
The expression of hamster sperm antigens was investigated during spermatogenesis and sperm maturation with the use of monoclonal antibodies generated in culture from mice immunized with hamster cauda epididymal spermatozoa or sperm heads. Antigens were localized by immunofluorescence and immunoperoxidase techniques which were first visualized on isolated spermatids over the developing acrosome. In one case, antibody inhibited fertilization in vitro although localization on testicular or epididymal spermatozoa was minimal compared with the early spermatid. Antibodies also recognized surface antigens first expressed in the epididymis whose localization on the spermatozoon altered during epididymal transit or incubation in capacitating medium. The results were discussed in relation to the expression and function of surface determinants on the haploid germ cell.
Both sexually mature and sexually regressed male golden hamsters were transferred to asymmetric skeleton photoperiods with night interruptions of varying duration, the short pulses occurring 14 h after "dawn." Testicular function and accompanying changes in follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone and spermatogenesis were observed. Sexually regressed animals exposed to a night-break of 6 seconds (sec) or longer exhibited maximal testicular development with a rapid rise in FSH secretion followed by a slower, more variable rise in LH. Full testicular size was achieved after 8 weeks. Night-breaks of 250 milliseconds (msec) or 1 sec induced testicular development and spermatogenesis but at a slower rate: levels of FSH and LH were still rising at the end of the experiment. Complete testicular maintenance was achieved by night-breaks of 1 sec or longer. Partial testicular regression was observed with a night-break of 250 msec. Night-breaks (60 sec) given less frequently than daily also stimulated testicular function and a night-break every 7 days increased FSH and LH secretion in sexually regressed hamsters, causing testicular development at a submaximal rate. Night-breaks given more frequently induced rapid testicular growth. Almost complete testicular maintenance of sexually mature hamsters was achieved with a 60-sec night-break at weekly intervals. Symmetric skeleton photoperiods also triggered testicular development in sexually regressed hamsters, with two 1-sec light pulses (14 h apart) being almost as effective as a normal long day. No difference in reproductive function was observed between animals on long days (14L:10D) and those exposed to maximally stimulatory skeleton photoperiods.
Pharmacological studies of ceftriaxone, a new semisynthetic cephalosporin, were conducted in 35 cancer patients. This antibiotic was administered in a variety of doses and schedules with no observed toxicity. Intramuscular administration of 500 mg of ceftriaxone to seven patients produced mean peak serum concentrations of 32.9 mug/ml 2.0 h after administration. The terminal serum half-life was 10.9 h. Intravenous infusion of 500 mg of ceftriaxone over 5 min to the same group of seven patients produced a mean peak concentration of the drug in serum of 83 mug/ml at the end of administration which decreased to 16.8 mug/ml at 8 h. A dose of 1 g of ceftriaxone given in identical fashion to the same group of seven patients produced mean peak concentrations in serum of 130 mug/ml at the end of administration and 17.3 mug/ml at 12 h. The mean percentages of drug recovered in urine 12 h after single intravenous doses of 500 mg and 1 g were 30 and 20%, respectively. A 1-g dose of ceftriaxone was administered every 8 h to 10 patients, and a 2-g dose was administered every 12 hours to 9 patients. Drug concentrations in serum were measured for each patient after drug administration on day 1, day 3 or 4, and day 7 or 8. The 1-g dose produced an observed mean peak concentration of 154 mug/ml and a mean terminal-phase half-life of 5.6 h on day 3 or 4. The 2-g dose produced a mean peak concentration in serum of 262 mug/ml and a terminal-phase serum half-life of 6.3 h on day 3 or 4. Continuous infusion studies were performed in nine neutropenic patients for up to 8 days by using a loading dose of 1 g over 30 min, followed by 2 g every 8 h. Mean concentrations in serum were maintained at about 135 mug/ml during the infusion period.
Golden hamsters were castrated and either maintained under short days of 9 h light and 15 h darkness (9L : 15D) or transferred to 12L : 12D, 13L : 11D or 16L : 8D. Plasma concentrations of FSH and LH remained low under 9L : 15D and 12L : 12D for 6-8 weeks but rose markedly within 4 weeks under 13L : 11D and 16L : 8D, suggesting a more abrupt transition between non-stimulatory and maximally stimulatory photoperiods than found in Japanese quail. Intact and castrated hamsters were exposed to natural photoperiods at a latitude of 51 degrees 27' N (Bristol) for 12 months. In the intact animals plasma FSH and LH levels and the size of the testes decreased as the daylength shortened from 12.5 to 10.5 h during autumn. This was followed by a rise in FSH output in mid-winter with an upward trend in LH secretion. The ensuing testicular recrudescence was complete before the spring equinox. The results emphasize that under natural conditions the primary factor regulating gonadal growth is the development of refractoriness to short days. In castrated hamsters there was no significant seasonal trend in LH output. Levels of FSH remained unchanged until a peak occurred in January, the same time that a peak was seen in intact animals before testicular recrudescence. A similar peak occurred in castrated hamsters maintained in 9L : 15D in the laboratory. This suggests that even in the absence of gonadal steroid negative feedback, hypothalamo-pituitary activity changes during the photorefractory period.
A 72-year-old patient with marked splenomegaly and low sphingomyelinase (6% of lowest control value) in peripheral blood leukocytes is described. Much higher but variable residual sphingomyelinase activity was observed in cultured skin fibroblasts (40-67% of lowest control value); reduced activity was also found in a liver biopsy sample. Excess storage of sphingomyelin was not observed in a liver biopsy; instead, a lipid tentatively identified as bis(monoacylglycerol) phosphate was present in amounts at least 20 times greater than in age-matched control livers. The biochemical relationship of this patient to patients with sphingomyelin storage disease (Niemann-Pick disease) and phospholipidosis Type II is discussed.
Reproductive activity in the Djungarian hamster, Phodopus sungorus, is suppressed by short daylengths and induced and maintained by long daylengths. To determine the time course of changes in plasma and pituitary gonadotrophin concentrations during the photoperiodic response, sexually immature male hamsters were moved from short (9L:15D) to long days (14D:10D). This induced an increase in testicular weight in 5 days and full sexual maturity in about 1 month. Plasma and pituitary FSH concentrations were significantly elevated after 3 and 5 long days respectively, reaching peak levels after 7--14 days and then declining. In contrast, pituitary and plasma LH concentrations did not increase until 10 and 21 days of photostimulation respectively. Castration of hamsters kept in short days led to a marked increase in plasma and pituitary FSH titres. Transfer to long days further increased plasma FSH although pituitary content did not change. Castration of hamsters kept in long days led to an elevation of plasma and pituitary FSH concentration to these same levels. Transfer to short days reduced plasma FSH to the levels seen in hamsters castrated and kept in short days. Pituitary content did not change. The results suggest that while there is substantial steroid negative feedback in intact animals on both long and short days, the photoperiodic modulation of gonadotrophin secretion does not necessarily involve changes in feedback sensitivity.
The major metabolic pathway of the (-) enantiomer and the (+) enantiomer of 2-hydroxy-N-cyclopropylmethylmorphinan in dogs was shown to be conjugation with glucuronic acid and/or sulfate. Gas chromatography mass spectrometry, nuclear magnetic resonance spectroscopy and X-ray crystallography were used to identify additional metabolites of the two enantiomers in dog urine after hydrolysis with Glusulase. Metabolites of the (-) enantiomer were identified as 2-hydroxymorphinan and 2,7beta-dihydroxy-N-cyclopropropylmethylmorphinan. The major metabolites of the (+) enantiomer in hydrolyzed dog urine were identified as 2-hydroxymorphinan,2,3-dihydroxy-N-cyclopropylmethylmorphinan and 2-methoxy-3-hydroxy-N-cyclopropylmethylmorphinan. In addition, tentative or partial structures were postulated for three minor metabolites of the (+) enantiomer: 2-methoxy-3-hydroxymorphinan, a metabolite containing a hydroxyl group on either carbon 4, 5, 6 or 7 and a methylated catechol metabolite containing a hydroxyl group on carbon 4, 5, 6 or 7. Thus, the major oxidative pathways of the (-) enantiomer were N-dealkylation and aliphatic hydroxylation, while the (+) enantiomer mainly underwent N-dealkylation and aromatic hydroxylation, followed by phenolic methylation. Analysis of urine from a human subject administered the (-) enantiomer suggested that the metabolism of this isomer by man was similar to its metabolism by dog.
Torula graminis produced blastoconidia in acropetalous chains after the evagination of a characteristic conidiogenous cell. Conidia consisted of up to 15 cells and their cell wall was differentiated into an outer melanized zone and an inner hyaline zone. A consistent cytoplasmic feature of conidial cells was the presence of dictyosomal-like membranous stacks often closely associated with the nucleus. Vesicles that developed from the dictyosomal-like cisternae were probably involved in conidial wall synthesis.
Torula thermophila produced typical chlamydospores either as intercalary chains within prostrate hyphae or as terminal swellings on short, lateral, hyphal branches. Mature chlamydo-spores were spherical, dark brown, smooth-surfaced structured structures with thick, single-layed cell walls (= secondary wall layer) usually differentiated into an outer electron-dense zone and an inner electron-transparent zone. Disarticulation and sport release occurred after the disintegration of the original hyphal wall. The thallospores of T. thermophila arise in a manner different from the blastospores produced by other species of Torula and are structurally more closely related to the spores produced by Humicola insolens. However until further work has been completed on spore development in the Torula-Humicola complex of fungi the name T. thermophila is retained.
Hyaline hyphae of Phomopsis become pigmented when exposed to short periods of light. Pigment was deposited in the form of melanin granules both within the cell wall and within mucilaginous excrescences that were developed irregularly over the hyphal surface. Analysis of the pigment showed it to have properties similar to that of "Dopa" melanin and to pigments previously isolated from fungal cell walls. Lysis of both hyaline and pigmented hyphal walls by means of lytic enzymes was minimal. It is suggested that the major role of melanin in this fungus is the protection of cellular organelles from harmful ionizing radiations.
Conidiogenesis in Torula herbarum and T. herbarum f. quaternella was observed by scanning and transmission electron microscopy. Conidia of the former were shown to be made up of three equally sized cells capped by a distinctive, and easily recognizable, conidiogenous cell. Conidiogenous cells also arose terminally on erect hyphae and on prostrate hyphae. The single-layered conidial cell walls were differentiated into an inner hyaline zone and an outer electron-dense zone formed by the deposition of melanin. Conidiogenous cells lacked melanin at the apex and, before conidiation, the lateral walls were strengthened by a further deposition of melanin. The apex bulged outwards and was modified into a new multicelled conidium bearing another apical conidiogenous cell. Continued development of new conidia resulted in an acropetal chain which became disarticulated after cytolysis within the conidiogenous cell. The relative distinctions between holoblastic and enteroblastic development are discussed and it is concluded that the conidia should be referred to as blastoconidia.
Conidia of Torula caligans (Batista & Upadhyay) M. B. Ellis comb.nov. and T. terrestris Misra were examined by transmission- and scanning-electron microscopy. Torula caligans produced four-celled conidia in which the central cells were distinctly larger than the basal and apical cells. Conidia of T. terrestris were 4- to 7-celled long and ellipsoidal in shape. Conidiogenous cells in both species developed melanin only within the lowermost part of the lateral walls while the other cells of the conidium were uniformly melanized around the circumference of the cell; melanin in these cells being deposited within, at least, half the width of the cell wall. In both species new conidia arose from evagination of the hyaline apex of the conidiogenous cell and are therefore blastoconidia. The systematic relationships between T. caligans and T. terrestris and other species of the genus Torula are discussed.
The 2 known host trees of Cryptococcus neoformans var. gattii, Eucalyptus camaldulensis and E. tereticornis, do not occur naturally in the 'Top End' of the Northern Territory (NT) of Australia. Nine clinical isolates of C. neoformans var. gattii from the NT were analysed by random amplification of polymorphic deoxyribonucleic acid (RAPD) and polymerase chain reaction 'fingerprinting'. Two isolates were assigned to RAPD profile VGI, previously established as the common RAPD profile. The remaining 7 were assigned to profile VGII; 6 of these isolates were recovered from individuals living in the 'Top End'. The results strongly support the existence of an alternative environmental niche for C. neoformans var. gattii, as all isolates from Eucalyptus spp. in Australia to date have been of RAPD profile VGI.