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Biomedical subjects

R M Clark

Publications and source records attributed to R M Clark.

At least 91 records · Page 5Linked to original sources
PubMed1984

Effect of temperature and length of storage on serum-stimulated and serum-independent lipolytic activities in human milk.

Milk was collected from five mothers. Upon collection, serum-stimulated and serum-independent lipolytic activities were determined. The milk samples were aliquoted and stored at 25, 4, -20, and -70 degrees C. After storage for 3, 6, 12, and 24 h, serum-stimulated and -independent activities were again determined and compared with the initial activities. Storage at 25 degrees C resulted in a significant (p less than 0.05) decrease in lipolytic activity. Serum-stimulated activity decreased 83.4% and serum-independent activity decreased 66.9% over the 24-h period. Storage at 4 degrees C resulted in a significant (p less than 0.05) decrease of 22.6% in serum-stimulated activity and a 7.2% decrease in serum-independent activity. No significant changes were observed in milk stored for 24 h at -20 and -70 degrees C. Milk was stored at -20 and -70 degrees C for an additional 1, 2, and 4 weeks. Serum-stimulated lipolysis did not change significantly over the 4-week period. Serum-independent lipolysis increased significantly (p less than 0.05) with storage time. Storage at -20 degrees C resulted in an increase of 20% and storage at -70 degrees C resulted in an increase of 36% over the 4 weeks.

Female↗
PubMed1984

Time course and prognosis of local recurrence following primary radiation therapy for early breast cancer.

The frequency, time course, and prognosis of local recurrence following primary radiation therapy in 152 patients with early breast cancer treated before 1967 were examined. Local recurrence occurred at a constant rate over the first 14 years after treatment. The crude 15-year local recurrence rate was 22%. Of the 30 patients who developed an isolated local recurrence and underwent definitive secondary surgery, the 10-year freedom from distant relapse rate was 50%. These results indicate that breast cancer patients treated by primary radiation therapy require long-term follow-up to detect curable local recurrences.

Breast Neoplasms↗
PubMed1983

Fulminating necrotizing amebic colitis with perforation: case report and review.

A seriously ill patient with diffuse abdominal tenderness of unknown cause is described. The diagnosis proved to be fulminating necrotizing amebic colitis with perforation. This case report serves as a reminder that amebiasis may occur in patients who have not been outside Canada, that it may readily be confused with other types of inflammatory bowel disease, and that particular care should be taken in obtaining a history of exposure. Before inflammatory bowel disease is diagnosed not only should the usual diagnostic tests such as stool examination and mucosal biopsy be done, but also serologic testing for amebiasis should be carried out.

Adult↗
PubMed1983

Ovarian irradiation and prednisone following surgery and radiotherapy for carcinoma of the breast.

Following mastectomy, patients with operable breast cancer underwent postoperative irradiation of the chest wall and regional lymph nodes. They were then assigned at random to receive no further therapy, ovarian irradiation (2000 rad in five days) or ovarian irradiation in the same dosage plus prednisone, 7.5 mg daily. A total of 705 patients received the randomly assigned treatment and were followed for up to 15 years. In premenopausal patients who received ovarian irradiation, the recurrence of breast cancer was delayed and survival prolonged, but not significantly. In premenopausal women aged 45 years or more, ovarian irradiation plus prednisone therapy significantly delayed the recurrence of breast cancer (p = 0.04) and prolonged survival (p = 0.02). No value was demonstrated for ovarian irradiation with or without prednisone therapy in postmenopausal patients.

Adult↗
PubMed1983

Determination of lipase specificity.

Specificity of lipases is controlled by the molecular properties of the enzyme, structure of the substrate and factors affecting binding of the enzyme to the substrate. Types of specificity are as follows. I. Substrate: (a) different rates of lipolysis of TG, DG, and MG by the same enzyme; (b) separate enzymes from the same source for TG, DG and MG. II. Positional: (a) primary esters; (b) secondary esters; and (c) all three esters or nonspecific hydrolysis. III. Fatty acid, preference for similar fatty acids. IV. Stereospecificity: faster hydrolysis of one primary sn ester as compared to the other. V. Combinations of I-IV. Lipases with these specificities are: Ia, pancreatic; Ib, postheparin plasma. IIa, pancreatic; IIb, Geotrichum candidum, for fatty acids with cis-9-unsaturation, and IIc, Candida cylindracea. III, G. candidum for unsaturates. IV. sn-1, postheparin plasma and sn-3 human and rat lingual lipases. V. Rat lingual lipase. Methods for determination involve digestion of natural fats of known structure and synthetic acylglycerols followed by analysis of the lipolysis products. All of the types of specificity have been detected with use of synthetic acylglycerols. Detection of stereospecificity requires enantiomeric acylglycerols which are difficult to synthesize, so other methods have been developed. These involve the generation of 1,2-(2,3)DG and resolution of the enantiomers. Trioleoylglycerol or racemic TG can be used as substrates. If the lipase is stereospecific, then either the sn-1,2- or 2,3-enantiomer will predominate. The relative amounts of the enantiomers can be determined by measurement of specific rotation, and nuclear magnetic resonance spectra. The DG can also be separated by conversion to phospholipids and hydrolysis with phospholipases A-2 or C. Applications of these procedures are discussed and data on the specificity of various lipases presented.

Animals↗
PubMed1983

Desmosterol in human milk.

Milk samples were collected from mothers at 2, 6, 12 and 16 weeks postpartum. Desmosterol was found to be present in all the milk samples. Identification of desmosterol was based on retention times with two gas liquid chromatography (GLC) columns and verified by GC-mass spectrometry. The concentration of desmosterol in breast milk increased significantly (P less than .05) from 0.6 mg/100 ml at 2 weeks to 1.3 mg/100 ml at 16 weeks postpartum. Desmosterol was not significantly correlated with total lipid, total cholesterol or free cholesterol in the milk.

Desmosterol↗
PubMed1983

Bile salt-stimulated lipase in human milk from 2 to 16 weeks postpartum.

Our objectives were to determine the change in bile salt-stimulated lipase (BSSL) activity in mature milk with time postpartum and to determine if BSSL activity was related to total lipid in the milk. Milk samples were collected from 12 mothers at 2, 6, 12 and 16 weeks postpartum. A significant (P less than .05) decrease in BSSL activity with time was observed. The average values expressed as mumol free fatty acids released/min/ml milk were 5.3, 4.5, 4.1 and 3.6 at 2, 6, 12 and 16 weeks postpartum. Total lipid in the milk increased significantly (P less than .05) from 4.1 g/dl at 2 weeks to 5.4 g/dl at 16 weeks postpartum but was not significantly correlated with BSSL activity.

Bile Acids and Salts↗
PubMed1983

Distribution of trans-octadecenoic acid in the major glycerolipids of human milk.

The intramolecular distributions of fatty acids in triacylglycerol, phosphatidylcholine, and phosphatidylethanolamine of human milk were determined. Milk donated from 10 mothers during their 2nd week of lactation was analyzed. Based on pancreatic lipase digestion of milk triacylglycerols, the 14:0 and 16:0 fatty acids were observed predominantly in the sn-2 position, while 18:0, 18:1, and 18:2 were observed predominantly in the sn-1,3 positions. The average trans-18:1 content of the triacylglycerols was 3.4% and was greater in the sn-1,3 positions. Phosphatidylcholine and phosphatidylethanolamine were digested by phospholipase A2. As in other tissues, saturated fatty acids were esterified at the sn-1 position and polyunsaturated fatty acids at the sn-2 position of the phospholipids. The proportion of trans-18:1 averaged 2.5% in phosphatidylcholine and 3.7% in phosphatidylethanolamine. The proportion of trans-18:1 was slightly greater in the sn-2 position of the phospholipids. In conclusion, there appeared to be a reverse positional distribution of saturated and polyunsaturated fatty acids in triacylglycerol compared to phosphatidylcholine and phosphatidylethanolamine. When compared to other mammalian tissues, there were only small differences observed in trans-18:1 content between positions within a glycerolipid class and between glycerolipids of human milk.

Adult↗
PubMed1983

Proliferating larval cestodiasis: report of a case.

A 72-year-old Filipino man who had emigrated to Canada had an abdominal infection with a proliferating acephalic larval cestode. Small, irregularly shaped parasites were within the substance of a lymph node, where they provoked a fibrogranulomatous and eosinophilic reaction. The parasite is described and is identified as an undifferentiated sparganum or tetrahyridium based upon comparison with two similar parasites from patients in Taiwan and Paraguay.

Aged↗
PubMed1983

Extranodal malignant lymphomas of the head and neck.

The management of primary extranodal lymphomas of the head and neck at The Princess Margaret Hospital is reviewed. This manner of presentation is uncommon and particularly rare in Hodgkin's disease. As with lymphomas at any other site, detailed investigation is necessary to determine the stage of the disease before definitive treatment is attempted. Surgery is normally restricted to biopsy. Radiation therapy and chemotherapy, alone or combined are the principal treatment modalities. Early disease (stages IA and IIA) may be treated by radiation alone with a cause specific survival of approximately 70% at five years and 60% at 10 years. Survival is better for histiocytic, nodular, and less bulky disease. Primary thyroid disease is uncommon but highly curable with local radiation. Similarly, orbital disease is usually locally curable with negligible sequelae. The addition of combination chemotherapy has significantly improved the prognosis with more advanced and bulky disease.

Adolescent↗
PubMed1982

Malignant tumors of the head and neck in a young population.

Malignant tumors in the head and neck region are rare in patients under the age of 30 years. The survival rate in our group compared favorably with the rate for adults with similar tumors and supports the administration of aggressive treatment. Radiation therapy in the formative years can arrest skeletal growth and cause tissue atrophy which produces facial asymmetry, but it does give in balance a better functional result and less mutilation than does radical surgery. The risk of development of a second malignant tumor with the administration of modern treatment appears to be minimal. There is an urgent need for better documentation of etiologic factors.

Adolescent↗
PubMed1982

Breast cancer: a 21 year experience with conservative surgery and radiation.

Evidence is presented from a study of 680 patients followed over a period of 21 years that conservative treatment of breast cancer by local excision of the primary tumor followed by breast irradiation yields results equivalent to the traditional radical approach, with the added benefit of an excellent cosmetic result and improved quality of life. The relative survivals were 8.3% at 5 years and 71% at 10 years. There was no difference in survival when radiation was given. Breast irradiation significantly reduced relapse in the breast, but axillary irradiation did not influence relapse at this site. Relapse in the breast alone was not detrimental to survival if treated appropriately. Axillary relapse indicated a much poorer prognosis as might be expected.

Brain Neoplasms↗
PubMed1982

The lipolytic triad: human lingual, breast milk, and pancreatic lipases: physiological implications of their characteristics in digestion of dietary fats.

The characteristics of human lingual, breast milk, and pancreatic lipases as related to the digestion of dietary fats in infants are discussed. The activity and specificity of these enzymes and structure of the dietary fats largely determine the rates of lipolysis, the types of digestion products formed, and the rates of absorption. Also possibly influenced are micelle formation, intestinal health, breast milk jaundice, and the absorption of other nutrients. In premature infants, the action of lingual and breast milk lipase are particularly important in the absorption of dietary fatty acids.

Bile Acids and Salts↗
PubMed1982

Changes in the lipids of human milk from 2 to 16 weeks postpartum.

Changes in total lipid, fatty acids, total cholesterol, free cholesterol, and lipid phosphorus in mature milk with time were investigated. Milk samples were collected from 10 mothers at 2, 6, 12, and 16 weeks postpartum. During 1 day, each mother donated two complete breast expressions. Expressions were taken using an electric breast pump 1 h after the previous a.m. and p.m. nursing. For each mother, the a.m. and p.m. samples were pooled for analysis. It was observed that the amount of total lipid increased significantly (p less than 0.05) from 3.9 g/100 ml at 2 weeks to 5.2 g/100 at 16 weeks postpartum. The total fatty acid composition remained uniform during the investigation. Average total cholesterol and free cholesterol in the milk were 10.3 mg/100 ml and 8.3 mg/100 ml, respectively. These concentrations did not change significantly with time postpartum. Average lipid phosphorus was 3.9 mg/100 ml and also remained constant throughout. We conclude that the fatty acid pattern, lipid phosphorus, total cholesterol, and free cholesterol of mature milk to 16 weeks postpartum remains relatively constant while total lipid concentration increases.

Cholesterol↗