PubMed Health⌕ Search

Biomedical subjects

C A McIntosh

Publications and source records attributed to C A McIntosh.

12 recordsLinked to original sources
PubMed1999

Flavanone-7-O-glucosyltransferase activity from Petunia hybrida.

Citrus spp. are known for the accumulation of flavanone glycosides (e.g., naringin comprises up to 70% of the dry weight of very young grapefruit). In contrast, petunia utilizes relatively more naringenin for production of flavonol glycosides and anthocyanins. This investigation addressed whether or not petunia is capable of glucosylation of naringenin and if so, what are the characteristics of this flavanone glucosylating enzyme. Petunia leaf tissue contains some flavanone-7-O-glucosyltransferase (E.C. 2.4.1.185) activity, although at 90-fold lower levels than grapefruit leaves. This activity was partially purified 89-fold via ammonium sulfate fractionation followed by FPLC on Superose 12 and Mono Q yielding three chromatographically separate peaks of activity. The enzymes in the peak fractions glucosylated flavanone, flavonol, and flavone substrates. Enzymes in Mono Q peaks I and II were relatively more specific toward flavanone substrates and peak I was significantly more active. Enzyme activity was not effected by Ca2+, Mg2+, AMP, ADP, or ATP. The petunia enzyme was over 10,000 times more sensitive to UDP inhibition (Ki 0.89 microM) than the flavanone-specific 7GT in grapefruit. These and other results suggest that different flavanoid accumulation patterns in these two plants may be partially due to the different relative levels and biochemical properties of their flavanone glucosylating (7GT) enzymes.

Flavonoids↗
PubMed1992

NAD-Linked Isocitrate Dehydrogenase: Isolation, Purification, and Characterization of the Protein from Pea Mitochondria.

The NAD(+)-dependent isocitrate dehydrogenase from etiolated pea (Pisum sativum L.) mitochondria was purified more than 200-fold by dye-ligand binding on Matrix Gel Blue A and gel filtration on Superose 6. The enzyme was stabilized during purification by the inclusion of 20% glycerol. In crude matrix extracts, the enzyme activity eluted from Superose 6 with apparent molecular masses of 1400 +/- 200, 690 +/- 90, and 300 +/- 50 kD. During subsequent purification steps the larger molecular mass species disappeared and an additional peak at 94 +/- 16 kD was evident. The monomer for the enzyme was tentatively identified at 47 kD by sodium dodecyl-polyacrylamide gel electrophoresis. The NADP(+)-specific isocitrate dehydrogenase activity from mitochondria eluted from Superose 6 at 80 +/- 10 kD. About half of the NAD(+) and NADP(+)-specific enzymes remained bound to the mitochondrial membranes and was not removed by washing. The NAD(+)-dependent isocitrate dehydrogenase showed sigmodial kinetics in response to isocitrate (S(0.5) = 0.3 mm). When the enzyme was aged at 4 degrees C or frozen, the isocitrate response showed less allosterism, but this was partially reversed by the addition of citrate to the reaction medium. The NAD(+) isocitrate dehydrogenase showed standard Michaelis-Menten kinetics toward NAD(+) (K(m) = 0.2 mm). NADH was a competitive inhibitor (K(i) = 0.2 mm) and, unexpectedly, NADPH was a noncompetitive inhibitor (K(i) = 0.3 mm). The regulation by NADPH may provide a mechanism for coordination of pyridine nucleotide pools in the mitochondria.

Journal Article↗
PubMed1992

Isolation and characterization of the tricarboxylate transporter from pea mitochondria.

The tricarboxylate transporter was solubilized from pea (Pisum sativum) mitochondria with Triton X-114, partially purified over a hydroxylapatite column, and reconstituted in phospholipid vesicles. The proteoliposomes exchanged external [(14)C]citrate for internal citrate or malate but not for preloaded d,l-isocitrate. Similarly, although external malate, succinate, and citrate competed with [(14)C]citrate in the exchange reaction, d,l-isocitrate and phosphoenolpyruvate did not. This tricarboxylate transporter differed from the equivalent activity from animal tissues in that it did not transport isocitrate and phosphoenolpyruvate. In addition, tricarboxylate transport in isolated plant mitochondria, as well as that measured with the partially purified and reconstituted transporter, was less active than the transporter isolated from animal tissues.

Journal Article↗
PubMed1990

Flavanone-specific 7-O-glucosyltransferase activity in Citrus paradisi seedlings: purification and characterization.

The isolation and characterization of a flavanone-specific 7-O-glucosyltransferase and its resolution from other glucosyltransferases in Citrus paradisi (grapefruit) seedlings is described. This new enzyme in the subclass 2.4.1 catalyzes the glucosylation of the 7-OH group of naringenin (4',5',7-trihydroxyflavanone) to prunin and has been purified (943-fold) by fractional precipitation with ammonium sulfate and successive chromatography on Sephadex G-100, hydroxyapatite, UDP-glucuronic acid agarose, Mono Q, and Mono P columns. It has a pH optimum of 7.5-8.0, an apparent pI of 4.3, and an apparent Mr of 54,900. This glucosyltransferase has an expressed specificity for the 7-position of the flavanones naringenin (Kmapp 62 microM; Kmapp UDPG 51 microM) and hesperetin (Kmapp 124 microM; Kmapp UDPG 243 microM) and did not accept other flavone or flavonol aglycones. Characteristics of other flavonoid glucosyltransferase activities found in grapefruit seedlings are also described.

Ammonium Sulfate↗
PubMed1988

Cystic change and neoplasia in isolated thyroid swellings.

During a 6-year prospective study of clinically isolated thyroid swellings (ITS), 148 (37 per cent) of 395 swellings were cystic as defined by the aspiration of fluid during fine needle aspiration cytology (FNAC). In the 106 (72 per cent) patients operated upon, 47 per cent of the cystic swellings were neoplastic and 14 per cent were malignant. In men 29 per cent of cystic swellings were malignant and 11 per cent in women. Only twelve cystic ITS were permanently abolished by aspiration and FNAC was inaccurate in predicting neoplasia. The incidence of malignancy in cystic ITS is higher than generally accepted and most cysts not abolished by aspiration should be removed.

Adenoma↗
PubMed1985

Continuing experience with single layer appositional anastomosis in the large bowel.

Results of continuing experience with single layer appositional anastomosis of the large bowel during 8 years (1977-84) were extracted from a prospective computerized audit of all abdominal operations under one consultant. After 204 elective operations mortality rate was 1.5 per cent: there were no deaths from anastomotic leakage. The total incidence of wound infection (including late infections) was 2.0 percent. The median duration of postoperative stay was 9.7 days and the mode 8 days. Three clinical anastomotic leaks (total incidence 1.5 per cent) occurred in 140 patients (2.1 per cent) after elective colorectal anastomoses. A restorative anastomosis was made in 86 per cent of patients with rectal carcinoma 6-12 cm from the anus and in 29 per cent with tumours below 6 cm. The overall incidence of a permanent stoma for rectosigmoid carcinoma was 19 per cent. 'Protective colostomy' and anastomotic drains were not used. The safety and applicability of single layer anastomosis in the rectum are compared with those of stapling.

Adult↗
PubMed1985

Naringin Levels in Citrus Tissues : II. Quantitative Distribution of Naringin in Citrus paradisi MacFad.

The quantitative distribution of the flavanone-7-neohesperidoside, naringin, in seeds, seedlings, young plants, branches, flowers, and fruit of Citrus paradisi Macfad., cv ;Duncan' was analyzed by radioimmunoassay. High levels of naringin were associated with very young tissue and lower levels were found in older tissues. Seed coats of ungerminated seeds and young shoots had high naringin concentrations whereas cotyledons and roots had very low concentrations. Light-grown seedlings contained nearly twice as much naringin as etiolated seedlings and, in young plants and branches, the naringin content was highest in developing leaves and stem tissue. In flowers, the ovary had the highest levels of naringin, accounting for nearly 11% of the fresh weight. There was a net increase in the total naringin content of fruits during growth. However, due to the large increase in fruit size, there was a concomitant decrease in the naringin concentration as the fruit matured.

Journal Article↗
PubMedDate not supplied

A comparison of the Glasgow Coma Scale and the Swedish Reaction Level Scale.

The Glasgow Coma Scale (GCS) and the Swedish Reaction Level Scale (RLS85), two level-of-consciousness scales used in the assessment of patients with head injury, were compared in a prospective study of 239 patients admitted to a regional head injury unit over a 4-month period. Assessments were made by nine staff members ranging from house officer to registrar, after briefing about the two scales. Data were also collected on age, nature of injuries, surgical treatment, and condition at discharge or transfer using the Glasgow Outcome Scale. Both the GCS and the RLS85 reliably identified comatose patients and those with minor head injury, but were much less effective in defining the response level in patients considered to have a moderate head injury. Only 41% of the patients allocated to a moderate-head-injury category by the GCS and the RLS85 were common to both groups. Where a mismatch occurred, neither scale allocated patients to a 'better' or 'worse' category more frequently than the other. Assessment of patients' conscious levels using the GCS was difficult in only two cases. One patient had facial injuries, and the other was intubated. The RLS85 was reported by all users to be simpler to use than the GCS, but the latter is much more widespread in use. Both scales function well in cases of severe and minor head injury, but have weaknesses when defining moderate head injury. Level-of-consciousness scales are only an aid to assessment and the final choice between the two scales must remain a matter of personal or departmental preference.

Activities of Daily Living↗