Biomedical subjects
R J Brown
Publications and source records attributed to R J Brown.
Eastern equine encephalomyelitis in an adult cow.
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Proteolytic activity of proteinases on macropeptide isolated from kappa-casein.
Proteolytic activities of chymosin, bovine pepsin, Mucor miehei rennet, Cryphonectria parasitica (formerly Endothia parasitica) rennet, trypsin, and chymotrypsin on kappa-casein macropeptide were measured. Macropeptide solutions (10 mg/ml of .05 M, pH 6.6 phosphate buffer) were incubated with the enzymes at 37 degrees C for various times, and their reactions were stopped by adding .025 ml of pepstatin (1 mg/ml of methanol). Peptides released from kappa-casein macropeptide were then fractionated using reverse-phase HPLC. At the pH of milk (pH 6.6), kappa-casein macropeptide was resistant to enzymic action by chymosin, bovine pepsin, and M. miehei and C. parasitica rennets. Bovine pepsin hydrolyzed kappa-casein macropeptide at pH 3. kappa-Casein macropeptide was readily hydrolyzed at pH 6.6 by trypsin and chymotrypsin. Possible physiological functions of the kappa-casein macropeptide are discussed in light of these findings.
Separation of beta-casein A1, A2, and B using cation-exchange fast protein liquid chromatography.
beta-Casein genetic variants A1, A2, and B were separated using cation-exchange fast protein liquid chromatography. beta-Casein from a herd bulk casein sample eluted as a series of three peaks. Casein samples from individual cows containing known combinations of beta-casein A1, A2, and B were used to confirm that the three peaks were beta-casein genetic variants. An acid-PAGE gel confirmed the identity of the peaks that eluted from the column.
Casein interference in bovine plasmin assays using a synthetic substrate.
Bovine plasmin (EC 3.4.21.7) activity on H-D-valyl-L-leucyl-L-lysyl-4-nitroanilide was measured by determining the change in absorbance at 405 nm. Initial rates of reactions were estimated at all combinations of the following substrate concentrations [.4, 4, and 40 times the substrate concentration at one-half maximum velocity (Vmax) (Km)] and casein concentrations [.068, .68, and 6.8 times the inhibitor constant for competitive inhibition (KI)]. By nonlinear least squares fitting of the data to an equation that described reversible enzyme kinetics, steady state kinetic parameters, maximum velocity (Vmax), substrate concentration at one-half maximum velocity (Vmax) (Km), inhibitor constant for competitive inhibition (KI), and inhibitor constant for uncompetitive inhibition (KI) were estimated. Casein fit the equation as a competitive inhibitor of bovine plasmin. This enzyme has a catalytic constant (Kcat) of .0158 change in absorbance at 405 nm/min per nM, substrate concentration at one-half maximum velocity (Vmax) (Km) of .107 mM substrate, and inhibitor constant for competitive inhibition (KI) of .86 mg/ml of casein. Bovine plasmin activity can be measured directly in bovine milk without interference from casein.
Explorations of a crisis intervention service.
Descriptive studies of a crisis intervention service replicated previous findings of relationships between staff members' attitudes towards treatment and their 'personal styles'. The attitudes and personal styles of crisis team members and non-members differed, largely because of differences in the professions making up these groups. While all staff groups shared the same concept of crisis, they differed in their discrimination of crisis cases from 'furores'. Initial crisis intervention interviews exhibited more confrontation and less exploration by therapists than did initial psychiatric out-patient clinic interviews. Patients referred to the crisis team differed from significant other people in their lives, and from control patients referred to the ordinary out-patient clinic, in aspects of their perception of problems.
Nondonor HIV antibody testing in Minnesota.
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Immobilization-associated osteoporosis in primates.
The progressive osteopenic changes in tibial compact bone in adult male monkeys (Macaca nemestrina) were examined histologically during chronic studies of immobilization. The animals were restrained in a semirecumbent position, which reduces normally occurring stresses in the lower extremities and results in bone mass loss. The longest immobilization studies were of 7 months duration. Losses of haversian bone tended to occur predominantly in the proximal tibia and were characterized by increased activation with excessive depth of penetration of osteoclastic activity. There was no apparent regulation of the size and orientation of resorption cavities. Rapid bone loss seen during 10 weeks of immobilization appeared to be due to unrestrained osteoclastic activity without controls and regulation, which are characteristic of adaptive systems. The general pattern of loss persisted throughout 7 months of immobilization. Clear-cut evidence of a formation phase in haversian bone was seen only after 2 months of reambulation. During this period osteoblasts accumulated within resorption cavities, and there was matrix apposition. Within 6 months of recovery there was increased bone turnover, and resorption cavities with diameters of 500-1500 micron were filled partially with new bone; the mean wall thickness of new bone was 2 to 3 times larger than normal. In addition there were numerous remodeling sites that were of normal size and orientation. Trabecular bone was lost during immobilization, and it is probable that losses of large trabecular plates are not replaced, and consequently original bone volume in the cross section is not recovered. In this immobilization model we observed bone resorption occurring for long periods without apparent interruption.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypnosis in Canadian criminal law.
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Effects of pH, calcium chloride, and chymosin concentration on coagulation properties of abnormal and normal milk.
Individual Holstein cow milk samples were selected for good and poor chymosin-coagulation characteristics. The effect of pH adjustment, addition of .02% calcium chloride, and variation in chymosin concentration on coagulation properties of good and poor coagulating samples was evaluated. Pooling 50% good and 50% poor coagulating samples did not improve the average coagulation properties of the poor samples. Reducing milk pH to 6.3 caused a significant decrease in coagulation time but a less marked increase in curd firmness. The greatest increase in curd firmness was obtained by a combination of reducing milk pH, addition of .02% calcium chloride, and reducing chymosin concentration. High-chymosin concentration at reduced pH decreased coagulation time without substantially increasing curd firmness. Curd disintegration was more apparent at high-chymosin concentration in the poor coagulating samples.
Perforated jejunal diverticulum presenting with a psoas abscess.
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Procedure for covalently immobilizing enzymes which permits subsequent release.
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Selection and pairing of 'normal' rhesus monkeys (Macaca mulatta) for research: procedures, techniques, and observations.
A selection process has been developed by the authors to insure investigators that animal subjects used in their experiments will accurately reflect biological changes associated with the project design. The procedure involved the following: complete physical examination; complete hemogram, serum electrolytes, serum biochemistry, body weight; and anthropometric determinations; aging by dentition; electrocardiography; total-body radiography; fecal culture; fecal ova, and parasite examinations; and examination of other conditions. Arithmetic means and standard deviations were calculated and used to eliminate monkeys whose values varied from the mean by more than two standard deviations.
A prolonged hematopoietic disturbance associated with aortic aneurism and splenomegaly in a squirrel monkey (Saimiri sciureus). A case report.
In a squirrel monkey (Saimiri sciureus), monitored clinically for five years, histopathological review revealed diffuse lymphoblastic lymphocytes infiltrating the thyroid, kidney, liver, pancreas, adrenal medulla, internal fat, extramedullary hematopoietic foci in the spleen and liver, and a mild chronic peritonitis.
Clinical description of tetanus in squirrel monkeys (Saimiri sciureus).
Nineteen cases of clinical tetanus developed in Bolivian squirrel monkeys (Saimiri sciureus) which were housed in outdoor corrals with soil-based floors. The disease was initially characterized by stiffness in gait followed by extensor rigidity, trismus and opisthotonus. Eleven of the 19 monkeys (58%) had evidence of external wounds. The case fatality rate was 100%. Tetanus accounted for 12% of adult female and 19% of adult male mortalities in the colony. Immunization with tetanus toxoid was effective in reducing the incidence of tetanus.
Fibrous osteodystrophy in a wild dolphin.
Skeletal lesions observed during necropsy of a wild mature male dolphin (Delphinus delphis) were consistent with fibrous osteodystrophy when examined microscopically. The lesions were pronounced in the ribs, scapulae, and pelvis, with no apparent skull or vertebral involvement. Whether the cause was nutritional or nonnutritional was not determined.
Neuroblastoma of the head and neck.
We reviewed 105 cases of neuroblastoma, which were seen at the Buffalo Children's Hospital between 1936 and 1976. We describe seven patients with primary neuroblastoma of the head and neck. The results of postmortem examination in two of these patients proved without any doubt that the tumor was primarily in the head and neck region. Although metastasis of neuroblastomas to the head and neck from more common primary sites in the abdomen, pelvis, or thorax is common, to our knowledge, well-documented primary head and neck lesions are quite rare. The prognosis of invasive neuroblastoma of the head and neck is poor, with rapid and widespread metastasis being the rule. However, some success has been reported with early and massive therapy that involves surgery, chemotherapy, and radiation therapy.