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Biomedical subjects

M Knight

Publications and source records attributed to M Knight.

At least 91 records · Page 5Linked to original sources
PubMed1978

Metabolic regulation in Pseudomonas oxalaticus OX1. Enzyme and coenzyme concentration changes during substrate transition experiments.

Metabolic control associated with diauxic growth of Pseudomonas oxalaticus in batch cultures on mixtures of formate and oxalate was investigated by measuring intracellular enzyme and coenzyme concentrations and QO2 values during transition experiments from oxalate to formate and vice versa. In transition from oxalate to formate oxalyl-CoA reductase concentration declined after the exhaustion of oxalate and ribulose-1,5-diphosphate carboxylase and 14CO2 fixation appeared upon addition of formate. In the reciprocal transition, ribulose-1,5-diphosphate carboxylase and 14CO2 fixation rate declined sharply after formate exhaustion, and oxalyl-CoA reductase appeared only after addition of oxalate. The intracellular NAD and NADP concentrations measured in the same experiments are reported. At substrate exhaustion the proportion of NAD in the reduced form fell from 15-20% to 2%. On addition of formate to an oxalate-starved culture there was an immediate increase in the proportion of NADH to 50%; such an increase was not observed in the reverse experiment.

Aldehyde Oxidoreductases↗
PubMed1978

Combination chemotherapy and radiation therapy of undifferentiated small cell bronchogenic carcinoma.

We reviewed 76 cases of small cell bronchogenic carcinoma seen at the University of South Florida Medical Center. One third of the 55 patients who have subsequently died did so within one month of diagnosis. Thirty-five patients were treated with cyclophosphamide, adriamycin, vincristine, and radiation therapy including prophylactic cranial irradiation. Of these 35 patients, 40% demonstrated a complete remission for a total objective response rate of 63%. The projected median survival of patients referred for study is 14 months. Improved survival was found in patients less than 60 years of age, with limited disease, who responded to treatment and in whom there were no violations of protocol. Patients treated with combination therapy appear to survive longer than untreated patients and those treated with radiation therapy alone. Toxicity was tolerable and there were no deaths related to treatment. Small cell bronchogenic carcinoma is a rapidly progressive systemic disease responsive to multimodality therapy with long-term survival in some patients.

Adult↗
PubMed1977

Volvulus of the sigmoid colon.

The clinical presentation and treatment of 31 consecutive patients with sigmoid volvulus are reviewed. Nearly half of these patients had a history of mental illness and one-third of all patients were chronically constipated. The main clinical features of abdominal pain and gross abdominal distension had been present for an average of 8 days before presentation of the patient to hospital. The clinical diagnosis of sigmoid volvulus was not difficult but the presence of non-viable bowel was more difficult to establish. A silent abdomen was the most valuable indication of the presence of gangrenous bowel. Conservative measures, including sigmoidoscopy and therapeutic barium enema, successfully reduced the volvulus in half of the cases so treated. In those patients undergoing surgery the procedure associated with the lowest mortality was sigmoid resection with end-to-end anastomosis. The overall mortality was 35%.

Adult↗
PubMed1976

Ultraviolet susceptibility of BCG and virulent tubercle bacilli.

To test the effectiveness of irradiating the upper air of a room with ultraviolet light at reducing the concentration of airborne tubercle bacilli, the susceptibility to the germicidal effects of ultraviolet light, Z, was determined for various mycobacteria. Virulent tubercle bacilli and bacille Calmette-Guérin (BCG) were equally susceptible to ultraviolet radiation, whereas Mycobacterium phlei had 10 times their resistance (Z, approximately one-tenth that for M. tuberculosis). The effectiveness against BCG of upper air ultraviolet irradiation in a room was tested directly by nebulizing BCG into the air of the room and monitoring its rate of disappearance. With one 17-watt fixture operating, the rate of disappearance increased 6-fold; with 2 fixtures operating (46 watts total), the rate of disappearance increased 9-fold. This implies that under steady-state conditions, the concentrations of airborne organisms with ultraviolet light(s) on would have been one-sixth and one-ninth, respectively. The increase in rate of decay of the airborne organisms using 1 fixture was equivalent to 10 air changes per hour, whereas that using 2 fixtures was approximately 25 air changes per hour (range: 18 to 33 air changes per hour). These increments are less than those reported previously for Serratia marcescens, because the Z value for BCG is approximately one-seventh that for serratia. These findings with BCG are believed to be directly applicable to virulent tubercle bacilli.

Air Microbiology↗
PubMed1974

Music therapy.

Explore the source record for details and available documents.

Blindness↗
PubMed1973

Measurement of methaemalbumin in plasma.

Using the method of Chong and Owen (1967), the normal range of methaemalbumin in plasma was 0 to 0.6 mg/100 ml, expressed as milligrams of haematin per cent. Previous results, using the method of Shinowara and Walters (1963), reported a normal range of 0 to 8.0 mg/100 ml, but it was expressed as milligrams of haemoglobin percent. The conversion factor from the Shinowara method is as follows: mg haematin % = mg haemoglobin % x 0.04.

Heme↗
PubMed1972

The bacterial oxidation of picolinamide, a photolytic product of Diquat.

The pathway of oxidation of picolinamide (pyridine-2-carboxamide) by a Gram-negative rod has been elucidated. Under conditions of high pH, restricted aeration and high substrate concentration, whole cells released 2,5-dihydroxypyridine into culture supernatants. Sodium arsenite at 5mm caused whole cells to accumulate 6-hydroxypicolinate, and, at 1mm, pyruvate, in culture media. Whole cells oxidized picolinamide, picolinate, 6-hydroxypicolinate, maleamate and maleate without lag. Cell-free extracts converted picolinamide into picolinate, and hydroxylated picolinate to 6-hydroxypicolinate. The hydroxylase was particulate, but could be solubilized by ultrasonic treatment; it required NAD(+) for activity, and did not require molecular oxygen. 2,5-Dihydroxypyridine was converted into maleamate and formate by an oxygenase requiring GSH and Fe(2+). Maleamate was deamidated to maleate, and maleate isomerized to fumarate, by unsupplemented extracts.

Amides↗
PubMed1972

The bacterial oxidation of N-methylisonicotinate, a photolytic product of paraquat.

Two bacteria have been isolated that are capable of oxidizing N-methylisonicotinate, a photodegradation product of Paraquat (1.1'-dimethyl-4,4'-bipyridylium ion). N-Methylisonicotinate-grown cells of strain 4C1, a Gram-positive rod, oxidized 2-hydroxy-N-methylisonicotinate without lag. Cell-free extracts of these cells converted 2-hydroxyisonicotinate into 2,6-dihydroxyisonicotinate; the reaction did not require molecular oxygen. Maleamate was deamidated and maleate isomerized to fumarate by soluble enzyme systems. [(14)C]Formaldehyde was isolated as the dimedone derivative from the supernatant of a cell suspension oxidizing N-[(14)C]methylisonicotinate, and no [(14)C]-methylamine was detected. Whole cells incubated with N-methyl[carboxy-(14)C]isonicotinate released 95% of the radioactivity as (14)CO(2). The second bacterium, strain 4C2, a Gram-negative rod, did not oxidize any of the mono- or di-hydroxypyridines or their N-methyl derivatives that were available or could be synthesized; nor did cell-free extracts oxidize any of these compounds. Methylamine was oxidized by whole cells without lag; cell-free extracts converted methylamine into formaldehyde when a soluble enzyme system requiring an electron acceptor was used; formaldehyde was oxidized to formate and formate to CO(2) by enzyme systems requiring NAD(+).

Bacteria↗
PubMed1972

A heat-stable nicotinamide-adenine dinucleotide glycohydrolase from Pseudomonas putida KB1. Partial purification and some properties of the enzyme and an inhibitory protein.

A thermostable NAD(P)(+) glycohydrolase (EC 3.2.2.6) detected in cell-free extracts of Pseudomonas putida KB1 was purified to a single component on polyacrylamide-gel electrophoresis. A heat-labile inhibitor of the enzyme was also partially purified. Enzyme free of inhibitor is present in culture supernatants. After an ultrasonic treatment enzyme-inhibitor complex and excess of inhibitor are present in both the cell-debris and soluble fractions. The general properties of the enzyme and inhibitor are described. The molecular weights of enzyme, inhibitor and enzyme-inhibitor complex, determined by gel filtration are about 23500, 15000 and 35000 respectively. The binding of inhibitor and enzyme is inhibited by the presence of substrate.

Cell-Free System↗