Biomedical subjects
Publications and source records attributed to D M Adams.
The theoretical basis for boron neutron capture therapy (BNCT) derives from the reaction that occurs when a stable isotope, boron-10, is irradiated with thermal neutrons to produce an unstable intermediate, boron-11, which then undergoes instantaneous nuclear fission to yield lithium-7 and alpha particles.
Explore the source record for details and available documents.
Ninety-two British, caucasian, alcoholic patients with liver disese were grouped on the basis of hepatic histology into fatty change, hepatitis with or without cirrhosis, and cirrhosis alone. Men with alcoholic hepatitis with or without cirrhosis showed an increased incidence of the histocompatibility antigen HLA-B8 (P less than 0.02). Increased measles antibody titres were found in patients without cirrhosis with or without hepatitis and were associated with the B8 phenotype in both sexes. Rubella antibody titres and percentage DNA-binding were raised in patients with cirrhosis and showed no association with the B8 phenotype. Concentrations of IgM and IgA were were raised in patients with stetosis and with hepatitis, while in patients with cirrhosis IgG concentrations were also increased. Low titres of autoantibodies were found in all histological groups. It is possible that the development of hepatitis in response to alcohol abuse may be influenced, at least in men, by a gene linked to the B locus. Otherwise, immune processes associated with alcohol-related liver disease are probably secondary phenomena.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Thermal inactivation at 110-150 degrees C of thermolysin (EC 3.4.24.4), produced by the thermophile Bacillus thermoproteolyticus, and the extracellular protease of Pseudomonas sp. MC60 a psychotroph, were investigated at 130 degrees C, both enzymes had approximately the same deltaH (22 kcal/mol) and deltaS (-13.5 cal/mol per degree) values. Both enzymes contain zinc and calcium. The amino acid compositions of the enzymes were similar except that MC60 protease exhibited a more typical tyrosine content. Comparable heat resistance at extreme temperatures of enzyme produced by psychrotrophic and thermophilic organisms emphasizes the difference between molecular properties that resist denaturation at elevated temperatures and those that allow reversible denaturation.
Explore the source record for details and available documents.
The heat-stable extracellular protease of Pseudomonas sp. (isolate MC60) was investigated. Heat resistance of the enzyme in milk at sterilization temperature was dependent on the presence of Ca2+. The half-life of the enzyme at ultrahigh temperature (149 C) in skim milk or milk-salts buffer with Ca2+ was approximately 7.0 s. Treatment of milk with chelators completely removed the heatstabilizing effect of milk. The enzyme was partially purified by ammonium sulfate precipitation and column chromatography on Sephadex G-100. At 21 C the enzyme retained greater than 85% activity after exposure to pH values between 5 and 10. Enzyme activity was reduced by metal chelating agents. Both Ca2+ and Zn2+ were required for optimal enzyme activity. Molecular weight was estimated at 48,000 by gel filtration.
Clostridium perfringens spores were injured by ultrahigh-temperature treatment at 105 C for 5 min. Injury was manifested as an increased sensitivity to polymyxin and neomycin. Since many of the survivors could not germinate normally the ultrahigh-temperature-treated spores were sensitized to and germinated by lysozyme. Polymyxin reportedly acts upon the cell membrane. Neomycin may inhibit protein synthesis and has surface-active properties. Injured spores were increasingly sensitive to known surface-active agents, sodium lauryl sulfate, sodium deoxycholate, and Roccal, a quaternary ammonium compound. Injured spores sensitive to polymyxin and neomycin also were osmotically fragile and died during outgrowth in a liquid medium unless the medium was supplemented with 20% sucrose, 10% dextran, or 10% polyvinylpyrrolidone. The results suggested that a spore structure destined to become cell membrane or cell wall was the site of injury. Repair of injury during outgrowth in the presence of protein, deoxyribonucleic acid, ribonucleic acid and cell wall synthesis inhibitors was consistent with this hypothesis.
Explore the source record for details and available documents.
The effects of psychrotroph growth in raw milk on proteins of mils and on the response of milk proteins to heat treatments with ultrahigh temperature were studied. Ten gram-negative psychrotrophs isolated from raw milk readily attacked raw milk proteins. Kappa- and beta-casein were most susceptible although some of the isolates also attacked the whey proteins. Detectable proteolysis did not require large psychrotroph populations. A 10 to 20% decrease in kappa-casein during 2 days at 5 C accompanied growth of one isolate to a population of only 10,000/ml. Growth of psychrotrophs in raw milk predisposed the proteins to deleterious effects of ultrahigh temperature treatments. Ultrahigh temperature treatment by direct steam injection had little effect on raw milk caseins and decreased alpha-lactalbumin and beta-lactoglobulin by 21% and 34%, respectively. Milk that had undergone proteolysis exhibited decreased detectable kappa-, beta-, and alphas-caseins and increased loss of beta-lactoglobulin as a result of ultrahigh temperature treatment. Milk suffering extensive kappa-casein degradation coagulated during ultrahigh temperature treatment. Coagulation during or shortly after heating increased with severity of heat treatment and size of psychrotroph population.
Explore the source record for details and available documents.
The identification and measurement of suspected hearing loss in pediatric patients presents a formidable challenge to the physician. Since he is responsible not only for determining the nature and extent of the hearing deficit, but also for overall management throughout the patient's learning life, an early and accurate diagnosis of the loss is mandatory.
The list of differential diagnoses in the case of midline facial granulomatous lesions is long. Intensive investigation into the true origin of disease must be done before definitive treatment can be begun. Extensive and repeated biopsies are necessary. The diagnosis may narrow down to the nonspecific midline lethal granuloma. Evidence in the literature coupled with our experience strongly indicates that this disease does not exist as a pathologic entity but merely as a clinical syndrome which upon further evaluation will reveal either Wegener's granulomatosis or a reticulum cell neoplasm. Treatment of the syndrome consists of corticosteroid drugs, irradiation, and chemotherapy until a definitive diagnosis is made. Midline granulomas have been and will continue to be a challenging diagnostic and therapeutic problem for the otolaryngologist.
Clostridium perfringens strain NCTC 8798 spores were injured by ultrahigh temperature treatment and were unable to outgrow in the presence of antibiotics used in selective enumeration media. Injured spores underwent repair in a nonselective laboratory medium and in foods.
Production of heat resistant proteases by psychrotrophs growing in milk, resistance of such proteases to ultrahigh temperature treatments and action of these enzymes on milk were studied. All of the psychrotrophs obtained from raw milk produced proteases that survived 149 C for 10s. Seventy to ninety percent of the raw milk samples contained psychrotrophs capable of producing heat resistant proteases. The protease chosen as a model was resistant to heat treatments at 110 to 150 C, and the inactivation parameters suggested that thermal destruction of heat resistant proteases would damage the milk severely. The casein content and pH of normal milk were suitable for protease action, and the protease was quite active at normal and elevated room temperatures. The protease rapidly spoiled sterile milk with the development of bitter flavor, clearing, or coagulation; and the susceptibility of sterile milk to protease increased during storage of the milk.
A densitometer composed of a microscope and a colorimeter is described. Results obtained with the microscope densitometer and with a standard densitometer compare favorably.
The requirement of ultrahigh temperature (UHT)-treated Clostridium perfringens spores for lysozyme and the sensitivity of heated and unheated spores to lysozyme were studied. The UHT-treated spores requiring lysozyme for germination and colony formation originated from only a small portion of the non-UHT-treated spore population. This raised a question of whether the requirement for lysozyme was natural to the spores or was induced by the UHT treatments. However, these spores did not require lysozyme for germination before UHT treatment, which confirmed that the requirement for lysozyme had been induced by the UHT treatment. Only 1 to 2% of the spores were naturally sensitive to lysozyme; therefore, the mere addition of lysozyme to the plating medium did not permit the enumeration of all survivors. Treatment of UHT-treated spores with ethylenediaminetetraacetate (EDTA) sensitized the spores to lysozyme and increased by 10- to 100-fold the number of survivors that were detected on a medium containing lysozyme. Under the heating conditions used, spores that were naturally sensitive to lysozyme and spores that required EDTA treatment were equally heat resistant.