Inactivation of Hydrogenase in Cell-free Extracts and Whole Cells of Chlamydomonas reinhardi by Oxygen

O(2) irreversibly inactivates hydrogenase from Chlamydomonas reinhardi. The mechanism for the inactivation involves the reaction of one molecule of hydrogenase with one molecule of O(2) (or two oxygen atoms) in the transition complex of the rate-limiting step. The second order rate constant for this reaction is 190 atmospheres(-1) minute(-1) (1.4 x 10(5) molar(-1) minute(-1)). At levels above 0.01 atmosphere O(2), the increased numbers of O(2) molecules may compete for the site of inactivation hindering the proper orientation for inactivation of any one O(2) molecule and resulting in lowered rates of inactivation.CO is a reversible inhibitor of hydrogenase acting competitively against H(2). The K(i) for CO is 0.0010 atmosphere. CO antagonizes O(2) inactivation. In a period when complete inactivation by O(2) would usually occur, the presence of CO greatly reduces the inactivation rate.After 3 hours of adaptation in whole cells, the presence of H(2) lowers the rate of deadaptation of hydrogenase. Inasmuch as H(2) promotes increased O(2) uptake the cellular concentration of O(2) is likely to be lower. After 48 hours of adaptation O(2) uptake is reduced even when H(2) is present and the pattern of deadaptation under O(2) with and without H(2) and CO is qualitatively the same as observed for the inactivation of cell-free hydrogenase. The mechanism of inactivation of cell-free hydrogenase by O(2) may be the same as the mechanism for loss of hydrogenase during deadaptation in whole algal cells.

Karyotypic Studies on Cyclorana and Associated Genera of Australian Frogs

The taxonomic relationships of frogs from the genus Cyclorana are uncertain, for they share similarities with both the Leptodactylidae and the Hylidae. Karyotypic comparisons were made between seven species of Cyclorana and three species from the leptodactylid genera Notaden, Neobatrachus and Heleioporus. All Cyclorana species have 2n = 26, whereas the other species have 2n = 24. The position and type of secondary constrictions subdivide the species of Cyclorana into three groups. The similarity of chromosome morphology in these three groups with that of hylids suggests a close phylogenetic relationship. The major chromosome differences between Cyclorana and representatives from the leptodactylid genera suggests a fundamental dichotomy masked by adaptation to a fossorial mode of life.

The theory of tree bole and branch form

Working from the general postulate that natural selection of plant form operates so as to maximize the survival potential of a species, this paper examines the hypothesis that the mechanical support of tree foliage must approach optimality in the use of wood, i.e., that tree stems and branches will have "optimal form" with respect to the amount of support tissue. Mathematical models of bole and branch form are presented, based on the proposition that either wind or gravity are the primary limiting factors for tree size and shape. Predictions of trunk and branch diameter as a function of tree size were tested with dimensional measurements of Populus tremuloides. The individual stems were selected from close-grown stands of differing ages. For small and intermediate trees, trunk diameter is such that stems have only 1.6 times as much wood as the minimum required to keep the tree from buckling under its own weight due to elastic instability. Branch diameters are shown to be close to the minimum required to maintain the spatial position of growing branches, as well as withstand wind forces. This minimal branch cost not only reduces the load which the stem must support against elastic instability, but allows the crown to flex in high winds. The flexing, in turn, reduces the drag force exerted by the wind on the trunk. Thus, the hypothesis that the observed tree form is an optimal design cannot be rejected on the basis of these results. Additional studies are planned with respect to optimal foliage distribution.

Steroid priming of the luteinizing hormone response to luteinizing hormone releasing hormone

Perifusion experiments were performed to study the stimulatory effects of luteinizing hormone releasing hormone (LH-RH) on the release of LH from anterior pituitary tissue. Exposure of pituitary tissue from normal male rats to LH-RH (5 ng/ml for 5 min) induced a small release of LH; in tissue from ovariectomized rats receiving no pretreatment, the release was more than three times greater and in tissue from gonadectomized male or female rats pretreated with oestradiol benzoate and progesterone, the release was six times greater than that observed in normal rats. Further exposure of pituitary tissue from gonadectomized steroid-pretreated male and female rats to LH-RH (5 ng/ml) induced an increase in the level of LH even greater than that seen after the initial exposure (priming action of LH-RH); in tissue from ovariectomized rats receiving no pretreatment, less LH was released than after the first exposure to LH-RH and in tissue from normal male rats the response was unchanged.

Home Range and Activity Patterns of the Sand Goanna, Varanus gouldii (Reptilia: Varanidae)

The movements of two subspecies of the sand goanna, V. gouldii, were studied at two localities in South Australia. The estimated home ranges of individuals of V.g. rosenbergi differed considerably, the largest area being 25 times the size of the smallest. Daily activity areas varied with the season, being largest in summer and smallest in winter. There were distinct differences between the two subspecies in their activity patterns, V. g. rosenbergi being active throughout the year whereas Kg. gouldii remained underground during winter.

Ocean Wave Patterns Under Hurricane Gloria: Observation with an Airborne Synthetic-Aperture Radar

Surface imagery of ocean waves under Hurricane Gloria (September 1976) has been obtained with an airborne synthetic-aperture imaging radar. Observations were obtained over most of the area within a radius of 150 kilometers around the center of the eye. These direct observations made it possible to derive the wave patterns in the region around a hurricane eye.

Pathological and therapeutic consequences of sleep loss: a review

Until recently sleep deprivation has been studied from the point of view of determining whether or not it produces deleterious effects. Evidence, however, has begun to accumulate indicating that both REM deprivation and single night sleep deprivation may have antidepressant effects. Although beneficial effects are found primarily in endogenously depressed patients, variable results have been obtained in both "endogenous" and "reactive" depressions, suggesting that these diagnostic categories include biologically heterogeneous populations.

The adverse effects of elemental diets on tolerance for 5-FU toxicity in the rat

The effects of a group of elemental diets on the gastrointestinal toxicity of 5-FU in the Sprague-Dawley rat were evaluated. Diarrhea, stomatitis, hypoalbuminemia, and early deaths were more frequent in the animals on elemental diets than in those consuming standard rat chow. Sepsis and hypoalbuminemia were directly related to the extent of protein hydrolysis of the particular elemental diet.

An additional chromosome race of Phyllodactyllus marmoratus (Gray) (Reptilia : Gekkonidae) and its phylogenetic implications

This paper describes a fourth chromosome race of P. marmoratus. Specimens from this race have 2n = 32 chromosomes and occur in an isolated pocket in the south-west of Western Australia. It is believed that this race has been derived from the 2n = 34 form by an additional chromosome fusion.

Season of birth in schizophrenia: an Australian study

The authors have studied the season of birth in schizophrenics comparing those born in both southern and northern hemispheres. Their findings do not support the notion of seasonal variations claimed by other authors. The clinical significance of reports published in the literature is questioned.

Traumatic dislocation of the hip joint in children

Between 1949 and 1972, 24 children under the age of 16 years were admitted to Middlemore Hospital with traumatic dislocation of a hip. Half of these were between 12 and 15 years of age, and there was a predominance of boys in the ratio of 7:1. A survey of these children supports the view that the hip joint of a child becomes dislocated more readily than that of an adult.

Conduction velocity in the proximal segments of a motor nerve in the Guillain-Barré syndrome

Conduction velocity from spinal cord to axilla (estimated using the F wave) has been compared with conduction velocity from axilla to wrist (measured in the conventional manner) in the motor fibres of the ulnar nerve in 17 controls subjects and in 11 patients with the Guillain-Barré syndrome (GBS). In the patients with GBS the conduction velocity was, in general reduced to a similar extent in both the proximal and the distal portions of the motor fibres, suggesting that the disease process is usually diffuse. In two patients, however, the conduction velocity in the proximal segment was disproportionally reduced and in one of these the conduction velocity in the distal segment was normal. It is concluded that the estimation of conduction velocity in the proximal segments of motor nerves may be of value in the assessment of patients with GBS.

Lung biopsy in immunocompromised hosts

Ninety-five lung biopsy procedures in 78 immunocompromised patients yielded treatable diagnoses in 35 per cent of the needle aspirates, 46 per cent of the cutting needle biopsies and 65 per cent of the open thoracotomies. Complication rates of bleeding or pneumothorax were comparable to those previously described in nonimmunocompromised patients. In patients with coagulation defects, the risk of having bleeding complications was high. Among 44 patients with primary lymphoma, 22 (50 per cent) had a lymphomatous infiltrate in the lung. Twenty-two patients with severe hypoxemia were studied and their mortality, although significantly greater than in the patients without hypoxemia, was marginally improved when a treatable lung lesion was found. The over-all recovery rate was 70 per cent when a treatable diagnosis was made in contrast to 25 per cent when there was no specific diagnosis. Hence lung biopsy, particularly by thoracotomy, appears to be a valuable procedure in immunocompromised patients who have otherwise undiagnosable lung lesions.

Dumbbell neuroblastomas in children

A "dumbbell" neuroblastoma is a malignant neoplasm usually primary in the mediastinum or retroperitoneum with posterior extension through an intervertebral foramen to additional tumor within the spinal canal. Neurologic deficits are found in almost all cases. Nineteen patients with such tumors were reviewed with respect to diagnosis, management, and results. Treatment consisted of prompt laminectomy with total or subtotal excision of the extradural tumor. The primary tumor in the mediastinum or retroperitoneal area was removed at a second stage. All patients received postoperative radiation therapy. Eleven of the 17 patients observed more than two years are free of disease, a cure rate much higher than the overall experience with neuroblastoma. Substantial recovery of neurologic function occurred in most, but kyphoscoliotic deformities were a disturbingly frequent late complication.

Spontaneous and estrogen-produced tumors in Nb rats and their behavior after transplantation

Tumors in rats of the Nb strain, arising either spontaneously or after prolonged treatment with s.c. pellets of estrogen, were transplanted to establish whether hormone conditioning was required for their growth. Whereas all spontaneous tumors arising in males and many of those in females were autonomous on transplant, most of those arising in estrogenized rats continued to require hormones for growth after transplantation. The latter included carcinomas of the adrenal cortex, breast, pituitary ectopic tissue, ovary (thecomas), Leydig cells of testis, thymus, pancreas,salivary glands, oribital gland (fibroadenoma), liposarcoma, and lymphoma. Many of the tissues of origin of the tumors have not been considered to be under theinfluence of estrogens. A type of hormone-responsive tumor that was inhibited by estrogen and that grew only in normal rats is described. Ali estrogens tested, including estriol , were interchangeable in action. The incidence of the more common tumors of the adrenal, breast, and pituitary was very low in normal rats, but higher in females. All tumors were more common after estrogenization in both sexes, particularyly in older animals. The secretion of steroids and pitiutary hormones by many tumors led to obvious biological effects. Pituitary secretion led to severe lesions frequently associated with diseases in humans, but the signs of such diseases in the rat apparently were hormone dependent and disappeared if the tumor was removed. The overall results raised the possiblity that estrogens were not carcinogenic per se but stimulated the growth of previously altered cells and that, following their transplantation, this hormone requirement was retained. Irrespective of the mechanism of carcinogenesis, hormone-dependent tumor growth was not irreversible but was controlled in an unexpectedly wide spectrum of organs by exogenous estrogen. Host factors may play a major role in controlling the growth of many tumors and the ultimate course of the disease.

Chromosomal evolution in the lizard genus Varanus (reptilia)

The karyotypes have been determined of 16 of the 32 species of the genus Varanus, including animals from Africa, Israel, Malaya and Australia. A constant chromosome number of 2n = 40 was observed. The karyotype is divided into eight pairs of large chromosomes and 12 paris of microchromosomes. A series of chromosomal rearrangements have become established in both size groups of the karyotype and are restricted to centromers shifts, probably caused by pericentric inversion. Species could be placed in one of six distinct karyotype groups which are differentiated by these rearrangements and whose grouping does not always correspond with the current taxonomy. An unusual sex chromosome system of the ZZ/ZW type was present in a number of the species examined. The evolutionary significance of these chromosomal rearrangements, their origin and their mode of establishment are discussed and related to the current taxonomic groupings. The most likely phylogenetic model based on chromosome morphology, fossil evidence and the current distribution of the genus Varanus is presented.

WHO collaborative study on the sero-epidemiology of rubella in Caribbean and Middle and South American populations in 1968

Knowledge of the rubella antibody profiles of female populations of various ages and in various geographical areas is essential for an intelligent and effective administration of rubella vaccine. The investigation reported was undertaken to extend a previous WHO collaborative study to include additional areas of the Americas. As in the other mainland areas included in the earlier study, the presence of rubella haemagglutination-inhibiting antibody was found to be a likely event in over 80% of the females of child-bearing age in Argentina, Brazil, Chile, urban Peru (Lima) and Uruguay. Antibody rates were significantly lower in Jamaica, Panama, rural Peru and Trinidad. These data confirm and extend earlier findings of low levels of rubella immunity in certain island or isolated populations.

Radiotherapy in the management of leukemia

Localized radiation therapy directed to the spleen and other sites, supplemented by a whole-body radiation technique, appeared to increase survival time in the chronic leukemias. In recent years the alkylating drugs have provided a more convenient form of "whole-body effect", because treatment can be taken at home and yet observation maintained.Small or medium field radiation therapy remains the most efficient means of controlling localized leukemic infiltrations. Splenic irradiation has been used successfully in the control of hemolytic anemia occurring during the course of chronic leukemia where steroids have failed.Proper management of the leukemias requires close co-operation between the radiotherapist, internist and hematologist.

The osteology of the water skink, Lygosoma (Sphenomorphus) quoyii

The osteology of Lygosoma (Sphenomorphus) quoyii is described in detail from alizarin transparencies. The lizard is prevalent around Sydney and both juvenile and adult specimens were studied. Some comparisons are made with certain lacertilian skeletons described in the literature but the lack of osteological studies of other members of the genus Lygosoma and other genera of the Scincidae makes it difficult to assess the phylogenetic signifcance of the structures encounterd in the present study and impossible to establish the evolutionary position of L. quoyii within the Scincidae. Thus, no conclusions have been reached in this regard, but attention is drawn to those aspects of the skeleton of L. quoyii which may prove to be important phylogenetically.