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Biomedical subjects

D Pitt

Publications and source records attributed to D Pitt.

At least 37 records · Page 2Linked to original sources
PubMed1986

Oxidation of carbon sources via the tricarboxylic acid cycle during calcium-induced conidiation of Penicillium notatum.

The TCA cycle was examined during Ca2+-induced conidiation in Penicillium notatum over the 12-h period after addition of Ca2+ to vegetative cultures. Conidiation was independent of Ca2+ when certain intermediates and derivatives of the TCA cycle served as sole carbon sources. Arsenite and malonate augmented the effect of Ca2+ on conidiation but did not substitute for it. Mitochondria from vegetative cells had low rates of oxidation of TCA cycle intermediates and, with the exception of pyruvate, aconitate and glutamate, these were poorly linked to phosphorylation processes. Calcium ions affected mitochondrial function causing reduced oxidation of oxoglutarate, elimination of pyruvate oxidation and a decline in respiratory control of these substrates with increased oxidation of NADH and NADPH. Radiorespirometric studies and enzyme searches revealed a complete but weakly oxidative TCA cycle in vegetative cells. In Ca2+-induced cells oxoglutarate dehydrogenase activity was deleted within 6.5 h of Ca2+ addition and this was accompanied by establishment of an 'incomplete Krebs cycle'. Calcium-induced conidiation was associated with increased capacity for acetate and glutamate metabolism involving an activated glyoxylate shunt which may be related to enhanced biosynthetic demand. The metabolic basis of the Ca2+ effect on conidiation is discussed in connection with previous findings.

Arsenic↗
PubMed1985

Enzymes of gluconate metabolism and glycolysis in Penicillium notatum.

In addition to the ability of Penicillium notatum to grow on sucrose, glucose, fructose and gluconate, substantial growth occurred on 2-ketogluconate and 5-ketogluconate thereby indicating a diverse sugar metabolism. Cell-free extracts contained all the enzymes of the Embden-Meyerhof-Parnas pathway and for both oxidative and non-oxidative pentose phosphate metabolism. Despite inconsistencies in results between different assay methods for the conventional Entner-Doudoroff (ED) enzymes, the data indicated the route was enzymatically possible. Demonstrations of the activities of the enzymes of the non-phosphorylative equivalent of the ED pathway were achieved. No evidence was found of a phosphorylative linking enzyme between the two pathways. Both 2- and 5-ketogluconate reductases were detected along with gluconate dehydrogenase which suggested interconvertibility between the ketogluconates and gluconate. However, ketogluconokinase, responsible for the conversion of ketogluconate to 2-keto-6-phosphogluconate, was not detected. A scheme for the interrelationships of routes of gluconate metabolism is discussed.

Carbohydrate Metabolism↗
PubMed1985

Pathways of glucose catabolism and the origin and metabolism of pyruvate during calcium-induced conidiation of Penicillium notatum.

Experiments examined the metabolic basis of Ca2+-induced conidiation during the 12-h period following the addition of Ca2+ to 40-h vegetative cultures of Penicillium notatum. Vegetative mycelium had enzymic capacity for three routes of glucose catabolism viz. the Embden-Meyerhof-Parnas (EMP), pentose phosphate (PP) and the Entner-Doudoroff (ED) sequences. Inhibitors of EMP enzymes restricted vegetative growth more than that associated with conidiation whilst arsenate augmented the limited capacity of lower levels of Ca2+ to promote conidiation. Arsenite (5.6 mmol . l-1) partially blocked the metabolism of pyruvate and caused its accumulation, which was also promoted by Ca2+ alone. Arsenite did not induce conidiation in vegetative cultures but when combined with Ca2+ it enhanced conidiation. Radiorespirometry and the analysis of accumulated pyruvate, promoted by arsenite, indicated that approximately 54% of carbon was catabolized via combined EMP/ED routes and 46% by the PP pathway and subsequently via a weakly functional TCA cycle. Calcium-induced cultures swung to a primarily ED (25%) and PP (75%) based catabolism with low substrate level phosphorylation, including a facility for a non-phosphorylative ED route, and further diminished oxidative TCA capacity. Pyruvate accumulation in Ca2+-induced cultures coincided with the decline in activity of pyruvate dehydrogenase and a reduced capacity for gluconeogenesis, with other enzymes of pyruvate metabolism showing altered activities. These changes in enzyme activities, pyruvate accumulation and its subsequent metabolism were related to growth rate and the developmental cycle, and are discussed in conjunction with the regulatory role of calcium.

Calcium↗
PubMed1983

Genetic screening of newborn in Australia. Results for 1981.

Since screening of newborn infants for phenylketonuria (PKU) by the Guthrie bacterial inhibition assay was established in the 1960s, 3 017 703 infants have been tested in Australia. Two hundred and fifty-one cases of PKU (0.83/10 000) and six cases of the variant forms of malignant hyperphenylalaninaemia (MHPA) (0.02/10 000) have been detected. In 1981, 11 infants with PKU were detected. Screening for congenital hypothyroidism was carried out in seven States, and 66 new cases were detected in 1981 (2.13/10 000). In Adelaide, 154 310 infants have been tested for galactosaemia and a total of seven cases have now been detected (0.45/10 000). In New South Wales, 35 955 infants have been tested for cystic fibrosis of the pancreas, and 17 cases were found (4.73/10 000).

Australia↗
PubMed1982

Genetic screening of newborn in Australia: results for 1980.

Since screening of newborn infants for phenylketonuria (PKU) by Guthrie bacterial inhibition assay was established in the 1960s, 2779 790 infants have been tested in Australia. Two hundred and forty cases of PKU (rate: 1/11 582) and six cases of the variant forms of malignant hyperphenylalaninaemia (MHPA) (rate: 1/463 298) have been detected. In 1980, 18 infants with PKU were detected. Screening for congenital hypothyroidism was carried out in six centres, and 40 new cases were detected in 1980.

Australia↗
PubMed1981

Genetic screening of newborn in Australia: results for 1979.

Since screening of newborn infants for phenylketonuria (PKU) by Guthrie bacterial inhibition assay was established in the 1960s, 2 556 498 infants have been tested in Australia. Two hundred and twenty-two cases of PKU, and five cases of the variant forms of malignant hyperphenylalaninaemia (MHPA) have been found over this period, an incidence of 1/11 516 for PKU, and 1/511 300 for MHPA. In 1979, 18 infants with PKU and one with MHPA were detected. Screening for congenital hypothyroidism was carried out in four centres, and 28 new cases were detected in 1979 (an incidence of 1/5746).

Australia↗
PubMed1981

Further delineation of the C (trigonocephaly) syndrome.

This communication brings the number of recognized cases of the C (trigonocephaly) syndrome to 11. The pattern of findings includes an anomaly of the anterior cranium and frontal cortex (trigonocephaly), the root of the nose (broad nasal bridge, epicanthus, and short nose), and palate (thick anterior alveolar ridges); abnormalities of the limbs (polysyndactyly, bridged palmar creases, short limbs, and joint dislocations and/or contractures); visceral defects (congenital heart defects, cryptorchidism, and abnormal lobulations of the lungs and kidneys). Auricular, mandibular, skin, and genital abnormalities also occur. Consistent neurological findings are hypotonia, strabismus, and psychomotor retardation; seizures have been reported. Normal chromosomes, normal parents with multiple affected offspring, equal sex ratio of affected individuals, and consanguineous matings all support autosomal recessive inheritance of the C syndrome. In autopsied cases, there has been a suggestion of defective central nervous system myelination. About 1/2 of the case have died within the first year. All survivors have severe to profound mental retardation except for one child who has moderate retardation.

Abnormalities, Multiple↗
PubMed1981

Tetraploidy in a liveborn infant with spina bifida and other anomalies.

Although tetraploidy of human chromosomes (92,XXYY) has been described frequently in abortuses, only one example in a liveborn infant has previously been described. A second malformed infant with a complete tetraploid chromosome complement, who lived for 15 days, is reported. In addition to many of the malformations described in the first case, this infant also had a sacral myelomeningocele and skeletal anomalies. The probable origin of the tetraploidy was a failure of cytoplasmic cleavage at the first mitotic division of the fertilised ovum.

Abnormalities, Multiple↗
PubMed1979

Genetic screening of the newborn in Australia. Results for 1978.

Since screening of newborn infants for phenylketonuria (PKU) by Guthrie bacterial inhibition assay was established in the 1960s. 2 334 679 infants have been tested in Australia, and 208 cases of PKU detected (an incidence of 1/11 224). In 1978, 21 infants with PKU were detected. Screening for hypothyroidism was carried out in three States, and 29 cases of congenital hypothyroidism were detected in 1978 (an incidence of 1/5894).

Australia↗
PubMed1978

A simplified cardiac cannulation technique.

A technique for venous cannulation, left heart venting, and aortic root cannulation is described. It is simple and tidy and permits full mobility of the cannula with minimal manipulation and no blood loss.

Cardiac Catheterization↗
PubMed1977

Ultrastructural localization of acid phosphatase activity in root tips by the p-(acetoxymercuric) aniline diazotate reagent and a comparison with a Gomori procedure.

The localization of acid phosphatase was studied in root tip cells of pea and mung bean by use of a heavy metal azo-dye technique. Diazotized p-(acetoxymercuric) aniline in a post-coupling procedure, using naphthol AS-BI phosphate as substrate, yielded a fine particulate reaction product within vacuoles, intercellular spaces, multivesicular bodies and at various sites throughout the cytoplasm of pea root cells and differentiating mung bean protoxylem cells. An ultrastructural comparison with a modified Gomori lead-salt precipitation method revealed differences in the subcellular location of beta-glycerophosphatase and naphthol AS-BI phosphatase. The distribution of acid phosphatases within plant meristematic cells is discussed.

Acid Phosphatase↗