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Biomedical subjects

N D Carter

Publications and source records attributed to N D Carter.

At least 109 records · Page 6Linked to original sources
PubMed1984

Novel inhibition of carbonic anhydrase isozymes I, II and III by carbamoyl phosphate.

Carbamoyl phosphate has been shown to inhibit carbonic anhydrase (CA) isozymes CA I, CA II and CA III. This physiologically important molecule is the most potent, naturally occurring inhibitor of carbonic anhydrase yet found. It is also unique, among carbonic anhydrase inhibitors discovered hitherto, in that it inhibits the 3 isozymes with equal effect, despite their strikingly different properties. The results imply the participation of carbonic anhydrase in the regulation of substrate availability for the urea cycle.

Animals↗
PubMed1984

The mechanism of inhibition of ureogenesis by acidosis.

In perfused rat liver a decrease of cytosol pH, determined with pH-sensitive microelectrodes, from 7.2 to 6.85 is associated with a 50% fall in ureogenesis from ammonium chloride. In isolated rat hepatocytes the fall in ureogenesis due to acidosis is associated with decrease in the mitochondrial and cytosolic concentration of citrulline. Limitation of carbamoyl phosphate synthesis and thus citrulline supply could be responsible for the inhibition of ureogenesis observed.

Acidosis↗
PubMed1984

Plasma phosphoglycerate mutase as a marker of muscular dystrophy.

An elevation of phosphoglycerate mutase (PMG) has been detected in the blood plasma of the genetically dystrophic chicken and in Duchenne muscular dystrophy (DMD) patients. In the dystrophic chicken, plasma PGM in the pectoral muscle was simultaneously depressed to less than one-half that of the normal chicken. In a group of 9 DMD patients, plasma PGM activity was found to be significantly raised above the normal range. A survey of a small group of plasma specimens from human fetuses at risk for muscular dystrophy also suggested that PGM merits investigation as a potential adjunct to other diagnostic indices.

Animals↗
PubMed1984

Hormonal control of carbonic anhydrase III.

Using radioimmunoassay, the concentration of carbonic anhydrase III (CA III) in the livers of adult male rats was found to be approximately 30 times greater than that observed in mature females. Castration of male rats led to a marked reduction in liver CA III concentrations that could be partially restored to control levels by testosterone replacement. Administration of testosterone to ovariectomized female rats induced about a 5-fold increase in liver CA III concentration. Immunoprecipitational analysis of the products of liver mRNA translation in vitro with antiserum specific for CA III showed that hormonal control of the levels of CA III in rat liver is mediated by changes in the amount of translatable CA III mRNA. Marked changes in liver CA III concentrations were also observed in developing and aging male rats. Different control mechanisms appear to operate in mouse and man.

Aging↗
PubMed1984

Localization of human muscle carbonic anhydrase isozymes using immunofluorescence.

Human muscle sections were examined for the presence of carbonic anhydrase using fluorescent second antibody and antisera specific for the three isozymes, carbonic anhydrase I (CAI), carbonic anhydrase II (CAII), and carbonic anhydrase (CAIII). CAIII was present in all fibers, CAII only in the connective tissue, and CAI showed a weak association with the sarcolemma.

Carbonic Anhydrases↗
PubMed1983

Sexual differentiation of rat liver carbonic anhydrase III.

Using radioimmunoassay, the concentration of carbonic anhydrase III in the livers of adult male rats was found to be approx. 30-times greater than that observed in mature females. Castration of male rats led to a marked reduction in liver carbonic anhydrase III concentrations which could be partially restored to control levels by testosterone replacement. Administration of testosterone to ovariectomised female rats induced about a 5-fold increase in liver carbonic anhydrase III concentration. Immunoprecipitation analysis of the products of liver mRNA translation in vitro with antiserum specific for carbonic anhydrase III showed that hormonal control of the levels of carbonic anhydrase III in liver is mediated by changes in the amount of translatable carbonic anhydrase III mRNA. Marked changes in liver carbonic anhydrase III concentrations were also observed in developing and ageing male rats.

Age Factors↗
PubMed1983

Carbonic anhydrase III in Duchenne muscular dystrophy.

Plasma carbonic anhydrase III (CAIII) levels determined by radioimmunoassay have been compared, in detail, with creatine kinase (CK) as indices of Duchenne muscular dystrophy (DMD). CAIII levels were markedly elevated in all patients but variability of levels in a number of individual patients was higher than CK.

Adolescent↗
PubMed1983

Androgen-linked control of rat liver carbonic anhydrase III.

The concentration of carbonic anhydrase III (CAIII) in male rat liver was found to be 30 times greater than that in the female. Castration of male rats led to marked reduction in liver CAIII concentrations which could be partially restored to control levels by testosterone replacement. Marked developmental and senescence changes in liver CAIII were also observed in male rats.

Aging↗
PubMed1983

Carbonic anhydrase III in neuromuscular disorders.

Plasma carbonic anhydrase III (CAIII) and creatine kinase (CK) were measured in 44 patients with a variety of neuromuscular disorders. Markedly elevated CK levels were associated with similarly increased levels of CAIII. In 9 patients, only the CAIII was elevated, but in 2 patients only the CK was raised. The determination of plasma CAIII is thus an important index of muscle disorder and is probably more sensitive than CK.

Adolescent↗
PubMed1983

Benign X-linked myopathy with acanthocytes (McLeod syndrome). Its relationship to X-linked muscular dystrophy.

Two healthy men with McLeod syndrome, a rare X-linked recessive phenotype characterized by acanthocytosis and weakened red blood cell antigenicity in the Kell blood group system, have been investigated. Both men showed raised blood creatine kinase levels, with myopathic EMG abnormalities. Biopsies of the quadriceps muscle showed the features of an active myopathy although there was no clinical evidence of muscular abnormality. The combination of the association of membrane abnormalities in red blood cells and a myopathy in both McLeod phenotype and Duchenne muscular dystrophy suggests that these syndromes may be due to related genetic abnormalities. The genetic locus for McLeod phenotype is situated near the end of the short arm of the X chromosome. The locus for Duchenne muscular dystrophy is unknown but it has been postulated that it is also situated on the short arm of the X chromosome at Xp 21. The occurrence of a subclinical X-linked myopathy with acanthocytosis (McLeod phenotype) thus raises the possibility of a new approach to genetic investigations in Duchenne muscular dystrophy, and in the related milder forms of this disease.

Acanthocytes↗
PubMed1982

Zinc and carbonic anhydrase III distribution in mammalian muscle.

Zinc and carbonic anhydrase III measurement in human and rat muscle extracts indicate that: 1. About one fifth of zinc in human soleus is associated with carbonic anhydrase III isozyme, and even higher levels of zinc and carbonic anhydrase III are found in rat soleus, where about one half of the zinc is in carbonic anhydrase III. Other muscle was also analysed in a similar way, (see text). Heart is notable in containing lower levels of zinc but negligible carbonic anhydrase III. 2. Treatment of muscle with water or phosphate solutions showed that all the carbonic anhydrase III was water extractable, whereas significant zinc remained bound, but was partially extractable by phosphate solutions. 3. Dialysis of muscle extracts showed that whilst some zinc was dialysable, there was no significant contribution from the carbonic anhydrase III in the dialysed extract. EDTA enhanced the release of dialysable zinc from muscle extract. These findings are discussed in relation to muscle disease.

Animals↗
PubMed1982

Variation in the composition of breast milk during the first 5 weeks of lactation: implications for the feeding of preterm infants.

Milk samples were collected from 10 mothers by a standardised technique with complete expression of both breasts at each feed for 24 hours. Samples were obtained at 8 intervals during the first 36 days of lactation. Analyses were performed for trichloroacetic acid-precipitable protein, total protein, lactose, triglycerides, phospholipids, cholesterol, energy, sodium, potassium, calcium, magnesium, zinc, copper, pH, and osmolality. The results give a comprehensive picture of the development of milk composition from transitional to mature milk. The most striking feature of the results was the high degree of variation observed both between samples from the same mother and between samples from different mothers on the same day of lactation.

Female↗
PubMed1981

A comparison of protein concentrations and energy in breast milk from preterm and term mothers.

The concentrations of milk specific and plasma proteins were compared in milk from mothers of preterm and term infants. Energy content was also determined. Immunoglobulin A was significantly increased in preterm milk, but there was no difference in the concentration of any other proteins or in the energy content. Both protein and energy varied to a greater extent in samples of preterm milk. We propose a hypothesis to explain the higher concentration of total nitrogen reported in preterm milk.

Blood Proteins↗