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Biomedical subjects

R E Morton

Publications and source records attributed to R E Morton.

At least 73 records · Page 4Linked to original sources
PubMed1983

Inter-relationship of lipids transferred by the lipid-transfer protein isolated from human lipoprotein-deficient plasma.

In a previous study we demonstrated that highly purified lipid-transfer protein facilitated the transfer of triglyceride, cholesteryl ester, and phosphatidylcholine between plasma lipoproteins. It remained unclear, however, whether these lipids were transferred by independent sites on the lipid-transfer protein. To address this point, we have studied the protein-mediated transfer of triglyceride, cholesteryl ester, and phosphatidylcholine as a function of the concentration and lipid composition of donor and acceptor lipoproteins. Lipoproteins labeled in vitro, reconstituted lipoproteins of defined lipid composition, and phosphatidylcholine liposomes with or without triglyceride and/or cholesteryl ester have been used to investigate the inter-relationships of lipids transferred by the lipid-transfer protein. In studies of initial (less than or equal to 10-13%) transfer, we found that, although absolute transfer rates were affected, the ratio of cholesteryl ester to triglyceride transferred was independent of donor and acceptor lipoprotein concentrations and acceptor lipoprotein lipid composition. With reconstituted lipoproteins as donor, we demonstrated that this ratio was linearly related to the ratio of cholesteryl ester to triglyceride in the donor particle; the sum of triglyceride and cholesteryl ester transferred remained constant and independent of the lipid composition of the donor. Experiments with intact lipoproteins labeled in vitro and with small unilamellar vesicles in the presence and absence of p-chloromercuriphenylsulfonate, confirmed the interdependence of triglyceride and cholesteryl ester transfer. In contrast, under all assay conditions, no correlation was found between the amount of phosphatidylcholine transferred and the transfer of triglyceride and/or cholesteryl ester. We conclude that triglyceride and cholesteryl ester compete for transfer and that the extent of transfer for each lipid is determined by its relative concentration in the donor particle, whereas phosphatidylcholine transfer is independent of triglyceride and cholesteryl ester transfer. The data also strongly support the conclusion that lipid transfer protein promotes both the exchange and net transfer of triglyceride and cholesteryl ester and that the net transfer process proceeds by a reciprocal exchange of triglyceride and cholesteryl ester without net transfer of core lipid between lipoproteins.

Carrier Proteins↗
PubMed1983

Masking by internally generated noise and protection by middle ear muscle activity.

Gross auditory nerve action potentials to high-frequency clicks were recorded bilaterally from awake cats with unilaterally tenotomized middle ear muscles (MEM) during eating and during control quiet periods. Masking by internally generated noise associated with eating increased with decreases in click intensity, but did not differ in ears with intact and tenotomized MEM. Under the conditions of this study, non-reflex MEM activity does not appear to provide protection against masking by internally generated noise.

Action Potentials↗
PubMed1982

Exchange of retinyl and cholesteryl esters between lipoproteins of rabbit plasma.

Normal or hypercholesterolemic rabbit plasma stimulates the transfer of retinyl ester as well as cholesteryl ester from rabbit lymph chylomicrons, chylomicron remnants or from cholesteryl ester-rich plasma VLDL to the d greater than 1.019 lipoprotein fractions. The presence of p-chloromercuriphenylsulfonate does not inhibit the transfer of these esters. Partially purified lipid transfer protein from rabbit or from human plasma also accelerates the transfer of the above esters. Whereas the rabbit plasma transfer protein preferentially accelerates the transfer of retinyl ester, the human plasma transfer protein appears to have a somewhat greater stimulating effect on the transfer of cholesteryl ester from low- to high-density lipoproteins.

Animals↗
PubMed1982

Uptake and metabolism of free fatty acids by the Morris 7777 hepatoma and host rat liver.

The relative capacity of Morris 7777 hepatomas and livers of tumor-bearing rats to take up and subsequently metabolize intravenously injected radiolabeled free fatty acids was investigated. The objective was to determine differences in lipid metabolism which may affect the lipid composition previously observed in this tumor. Both tissues demonstrated comparable selectivity in the uptake of palmitate, linoleate and arachidonate from blood, although the hepatoma took up one-tenth as much free fatty acid per g wet wt as liver. A much greater percentage of fatty acid taken up by the hepatoma was converted to aqueous soluble radioactivity, perhaps the result of oxidation. In the hepatoma, palmitate was incorporated into phospholipid molecular species in a pattern similar to that observed for diglyceride, which suggested that phospholipid synthesis occurred predominantly de novo. On the other hand, in liver, a large percentage of palmitate was incorporated into polyunsaturated phospholipid molecular species that were not present in the diglyceride pool, which suggested significant incorporation by the acylation of monoacyl phosphoglycerides. These studies indicate that the specificity for the uptake of fatty acids was not different in the two tissues; however, the subsequent metabolic processes are markedly different.

Animals↗
PubMed1982

The diagnosis of urinary tract infection: comparison of urine culture from suprapubic aspiration and midstream collection in a children's out-patient department in Nigeria.

Suprapubic aspiration (SPA) was compared with midstream urine collection (MSU) in the diagnosis of urinary tract infection (UTI) in a busy paediatric out-patient department in Northern Nigeria, where usually only one specimen can be taken before starting antimicrobial therapy. SPA in 287 children was compared with 175 MSU collections. Urine was obtained at the first attempt in 260 (91%) SPA's which were easy to perform and safe. MSU collections were more difficult, particularly in the younger child. In 51 cases MSUs were compared with SPAs taken immediately before, and gave an accurate indication of urine infection with no false negative or positive cultures. It is concluded that when only one urine specimen can be collected before starting antimicrobial therapy, a single MSU specimen gives an adequate result if correctly collected and plated out. When accuracy of diagnosis is essential or if a MSU cannot be obtained, SPA is indicated. A white cell count on unspun urine proved to be the most successful sideroom test for urinary tract. Counts in excess of ten cells per mm3 were found in 62% of patients with positive cultures.

Child↗
PubMed1982

Frequency and clinical features of urinary tract infection in paediatric out-patients in Nigeria.

A survey of urinary tract infections (UTI) was conducted in a paediatric out-patient department in Northern Nigeria over six months. The most common presenting complaints of UTI were pyrexia of unknown origin (PUO) and mild diarrhoea. The frequency of symptomatic UTI in out-patients was estimated at 0.4%. Asymptomatic UTI was common in children with nephrotic syndrome (16%) and severe malnutrition (23%). Abnormalities of the urinary tract were found on I.V.P. in four out of twelve boys and one out of nine girls with symptomatic infection. Micturating cystograms (MCUG) were of less value because even if severe ureteric reflux was found, long term follow-up was not practical. Follow-up could be maintained with greater success from local clinics.

Child↗
PubMed1982

Correlation of fatty acyl composition of mitochondrial and microsomal phospholipid with growth rate of rat hepatomas.

This paper presents fatty acyl compositions of phospholipids derived from mitochondria and microsomes isolated from two Morris hepatomas, one with slow (9618A) and another with intermediate (7794A) growth rate, and from corresponding host livers. These were compared with previous data from our laboratory for the fast-growing Morris hepatoma 7777. In this group of three hepatomas of widely differing growth rate and differentiation, the faster the growth rate of the tumor, the larger the sum of the contents of 16:1, 18:1, and 18:2 and the smaller the sum of the contents of all polyunsaturated fatty acids with four or more double bonds per molecule. The former sum was generally higher and the polyunsaturate content lower in hepatoma organelles than in corresponding host liver organelles. The 18:0/18:1 ratio observed in hepatoma organelles was always significantly less than that in host or control liver organelles.

Animals↗
PubMed1982

Purification and characterization of lipid transfer protein(s) from human lipoprotein-deficient plasma.

Lipid transfer activities from human plasma have been characterized to determine whether triglyceride and cholesteryl ester transfer proteins are identical. After sequential purification by phenyl-Sepharose, CM-cellulose, chromatofocusing, and gel filtration, both triglyceride and cholesteryl ester transfer activities were purified approximately 15,000-fold compared to lipoprotein-deficient plasma, with a 14% recovery of both transfer activities. The gel filtration fraction showed two bands, Mr 58,300 and 66,400, as determined by electrophoresis in sodium dodecyl sulfate. Two samples, each containing predominately one of the two bands, were obtained by selectively combining the eluates from the gel filtration column. The specific activities of triglyceride and cholesteryl ester transfer promoted by the larger protein were within 10% of those for the smaller protein. The relative rates of transfer for cholesteryl ester, triglyceride, retinyl ester, and cholesteryl ether for each fraction were the same. The transfer of triglyceride by either the large or small molecular weight component was almost completely inhibited by mercurial compounds, whereas cholesteryl ester transfer was relatively unaffected. We conclude that triglyceride and cholesteryl ester are transferred by the same plasma protein(s).

Carrier Proteins↗
PubMed1981

A plasma inhibitor of triglyceride and cholesteryl ester transfer activities.

An inhibitor of triglyceride and cholesteryl ester transfer activities has been identified in the plasmas of several animal species. The inhibitor in human plasma has been separated from lipid transfer protein by chromatography on phenyl-Sepharose and CM-cellulose. The inhibitor is characterized as a protein with Mr approximately 35,000 and an isoelectric point of 4 or less. The inhibitor protein decreased the transfer of both triglyceride and cholesteryl ester between all pairs of very low, low, and high density lipoproteins. Although under most conditions the inhibition of triglyceride and cholesteryl ester transfer was similar, the degree of inhibition of lipid transfer was dependent on the lipoprotein pair studied.

Animals↗
PubMed1981

The separation of apolipoprotein D from cholesteryl ester transfer protein.

This study addresses the question of whether cholesteryl ester transfer protein and apolipoprotein D are identical. The data presented show that these two proteins do not co-purify during hydrophobic and cationic exchange chromatography and are readily separated by molecular sieve chromatography or electrophoresis. Furthermore, the precipitation of apolipoprotein D by specific antisera did not diminish the transfer activity of lipoprotein-deficient plasma. We conclude that apolipoprotein D and cholesteryl ester transfer protein have significantly different physicochemical properties.

Animals↗
PubMed1981

Pancreatic ascites: an unusual complication of hyperparathyroidism.

Pancreatic ascites is usually considered to be a sequela of chronic alcoholic pancreatitis. Our patient had pancreatic pseudocyst formation and pancreatic ascites after acute pancreatitis, the latter secondary to hypercalcemic pancreatitis and documented hyperparathyroidism.

Acute Disease↗
PubMed1979

The acyl-CoA desaturases of microsomes from rat liver and the Morris 7777 hepatoma.

We have investigated the role of the microsomal oxidative desaturase in defining the aberrant phosphoglyceride fatty acid composition of hepatomas. The microsomal delta 9-stearoyl-CoA, delta 6-oleoyl(linolenoyl)-CoA, and delta 5-eicosatrienoyl-CA desaturase activities were studied in control and host liver and in the poorly differentiated Morris 7777 hepatoma. The delta 9-stearoyl-CoA desaturase of the hepatoma was significantly decreased (42%) relative to control liver, yet the hepatoma specific activity was twice that of host liver. Additionally, the specific activity of the delta 9-stearoyl-CoA desaturase of the tumor was found to decrease with increasing tumor weight. Also this desaturase was inactivated by freezing and thawing. The delta 6-oleoyl(linolenoyl)-CoA and delta 5-eicosatrienoyl-CoA desaturases of the hepatoma were 39% and 4% of control, respectively. The electron transport components involved in the desaturase system were reduced, although this did not appear to be rate-limiting. In addition, two competing metabolic reactions which could lower the observed desaturase activities, hydrolysis of the thioester and incorporation of substrate acyl-CoA molecules into glycerides, did not appear to be responsible for the lowered desaturase activities of the tumor. Thus, it appears that reduced levels of the desaturases themselves may be responsible for the observed activities. These results indicate that the capacity of the hepatoma to biosynthesize polyunsaturated fatty acids is greatly reduced and this is consistent with the decreased polyene content observed in many neoplasms.

Animals↗
PubMed1977

Gastrocolic fistula secondary to benign gastric ulcer not operated upon: case report and review of literature.

A case report and review of the literature of benign gastric ulcer complicated by gastrocolic fistula are presented. Twenty-seven percent of patients were found to be receiving ulcerogenic medications. Only 15% of patients had previous histories of ulcer disease. Parameters most suggestive of a neoplastic process included palpable abdominal mass and unexplained anemia. Diagnosis is established by barium enema. Endoscopic biopsy and cytologic studies are useful in differentiating benign from malignant processes. Surgical management of benign ulcers complicated by fistula results in more than 90% survival.

Aged↗
PubMed1976

Pancreatic ascites: successful treatment with pancreatic radiation.

A 51-year-old man with clinical and laboratory findings consistent with the diagnosis of pancreatic ascites is reported. Response to usual medical measures was inadequate. Single-dose irradiation to the pancreatic area (550 rads) resulted in marked improvement in his ascites. Operative pancreatogram months later revealed no evidence of ductal leakage. Low-dose pancreatic irradiation may be a unseful therapeutic adjunct in the older, high-risk patient with pancreatic ascites in whom surgery is not considered feasible.

Amylases↗
PubMed1976

Systemic lupus erythematosus: unusual presentation with gastric polyps and vasculitis.

A case of SLE with the unique association of gastric polyps and vasculitis is reported. Gastrointestinal symptoms, surgical indications, and complications of SLE with gastrointestinal involvement are reviewed. The unusual patterns of ileus or lupus peritonitis secondary to mesenteric vasculitis must be differentiated from a true surgical emergency. Corticosteroids may be expected to produce rapid clinical improvement in the two former instances. Surgical exploration is reserved for those cases with clinical or radiologic evidence of uncontrollable hemorrhage, bowel perforation, or mesenteric infarction.

Adult↗