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Biomedical subjects

G Clifton

Publications and source records attributed to G Clifton.

At least 19 recordsLinked to original sources
PubMed1996

Cationic lipid-mediated NGF gene transfection increases neurofilament phosphorylation.

We examined the effect of cationic lipid-mediated gene transfection of nerve growth factor (NGF) in primary septo-hippocampal cell cultures. Rat NGF cDNA was subcloned into a pUC19-based plasmid containing a CMV promoter. Two days after NGF gene transfection in primary cell cultures, ELISA confirmed increases in NGF protein secretion from transfected cells. To study the biological effect of cationic lipid-mediated NGF gene transfection, we analyzed the amount of neurofilament protein from NGF-transfected cell cultures. Western blot and immunohistochemical analyses detected significant increases in the phosphorylated form of neurofilament proteins in the cultures after cationic lipid-mediated NGF cDNA transfection. Cationic lipid-mediated NGF cDNA transfection did rot cause significant changes in the total amount of neurofilament protein. Our studies suggest that cationic lipid-mediated NGF gene transfection can increase neurofilament phosphorylation but not total neurofilament protein.

Animals↗
PubMed1994

Optimizing liposome-mediated gene transfer in primary rat septo-hippocampal cell cultures.

Although liposomes have been widely employed to transfect DNA into a variety of cell types, no previous studies have systematically examined conditions producing optimal liposomal-mediated transfection of DNA into central nervous system (CNS) cells. Thus, we used the beta-galactosidase (beta-gal) reporter gene to examine factors influencing the efficiency of liposome-mediated gene transfection in CNS cell cultures. Our results indicate that without increasing the amounts of DNA, increased liposome concentrations within certain limits enhanced transfection efficiency. However, higher liposome levels could produce cell lysis. Without increasing liposome concentrations, increased amounts of DNA did not improve transfection efficiency. Employing the optimal concentration (1 microgram DNA/3 microliters liposomes/well), beta-gal gene expression was sustained for at least two weeks after transfection in primary septo-hippocampal cultures.

Animals↗
PubMed1994

Sustained expression of functional nerve growth factor in primary septo-hippocampal cell cultures by liposome-mediated gene transfer.

We examined liposome-mediated gene transfection of nerve growth factor (NGF) in primary central nervous system cultures. RT-PCR analyses detected increased expression of NGF mRNA one day after liposome-mediated NGF gene transfection. ELISA studies detected large increases in NGF protein in cells and in culture medium after NGF gene transfection. Cells continued to secrete NGF into the medium for at least 2 weeks. NGF bioassays confirmed that the NGF secreted after gene transfection was biologically active.

Animals↗
PubMed1989

The effects of enoximone on renal function in patients with congestive heart failure.

Enoximone is an investigational cardiotonic agent with positive inotropic and vasodilatory properties. In this protocol the effects of enoximone on parameters of renal function in patients (n = 14) with New York Heart Association class II or III congestive heart failure were determined after intravenous (IV) treatment (2 mg/kg) and after chronic oral administration (150 mg t.i.d.), either alone or with added furosemide (40 mg b.i.d.). Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), filtration fraction, mean arterial pressure (MAP), renal blood flow (RBF), and renal vascular resistance (RVR) were determined each time. Plasma volume (PV) was determined at baseline and after oral enoximone and after oral enoximone plus furosemide. Significant reductions in GFR (18%) and ERPF (20%) were observed after IV treatment but not after oral treatment with or without furosemide. MAP also was lowered significantly by 14% after IV administration but not after oral treatments. PV after oral enoximone plus furosemide was reduced significantly (31%) compared with baseline. These results demonstrate that enoximone produces acute reductions in GFR and ERPF when given intravenously but has no effect on parameters of renal function when given orally, either alone or with furosemide.

Adult↗
PubMed1986

CSF brain creatine kinase levels and lactic acidosis in severe head injury.

The posttraumatic creatine kinase-BB isoenzyme (CKBB) activity and lactate concentration in ventricular cerebrospinal fluid (CSF) have been studied in 29 patients with severe head injuries. The CKBB activity reaches its maximum a few hours after trauma, and has a monoexponential drop with a half-time of approximately 10 hours. Ventricular CSF lactate concentration continues to rise in patients with a poor outcome, and decreases only slowly and inconsistently in most of the other patients. Thus, increase of lactate in the ventricular CSF is not, like CKBB, a direct one-stage consequence of the trauma but is due to continuous production from a derangement of metabolism caused by the trauma. Since even higher ventricular CSF lactate levels can be survived when not caused by head injury, and since no significant pH changes were related to the ventricular CSF lactic acidosis in these artificially ventilated patients, it is concluded that ventricular CSF lactic acidosis is indicative of a severe, although not necessarily intractable, disturbance of brain function associated with intracellular lactate production and acidosis.

Acidosis, Lactic↗
PubMed1982

Developing a system of comprehensive care for the spinal cord injured patient in Houston, Texas, U.S.A.

The authors agree with the principle, widely accepted, that spinal cord injured (SCI) individuals should receive all their acute, rehabilitative and follow-up care in a spinal cord injury centre. The evolution of rehabilitation medicine and services in the United States, however, has favoured the separation of acute and rehabilitation care for spinal cord injured patients, as well as other disabilities. This has resulted partly from specialisation of medical and allied health personnel, physical separation of acute and rehabilitation facilities, and reluctance of some funders of health care to see rehabilitation as a natural extension of medical care in these patients. In Houston the proximity of a rehabilitation facility to three acute care university hospitals, representing three medical schools, provided an opportunity to improve communication among the medical personnel. These individuals have recognised the value of early rehabilitation even while the patient is acutely ill; they agreed to institute a system of care wherein the rehabilitation physician partakes in the early management in a designated area of the acute hospitals for spinal cord injured patients and works toward early transfer to the rehabilitation hospital in as ideal a condition as possible. Surgeons, who have initial primary responsibility, also visit the rehabilitation hospital, following their patient's progress at selected conferences and at the bedside. This paper describes how, a spinal cord injury service was established, how the major barriers to early transfer were confronted, and the results of the first 6 months of operation.

Comprehensive Health Care↗
PubMed1981

Effects of labetalol and methyldopa on renal function.

Renal function studies were performed in subjects with mild hypertension treated with labetalol (n = 5) and moderate to moderately severe hypertension treated in a random double-blind fashion with either labetalol (n = 6) or methyldopa (n = 6). Drugs were given in doses sufficient to reduce standing diastolic blood pressure to less than 90 mm Hg. This was achieved in all subjects without significant side effects. Inulin clearance, para-aminohippurate clearance, filtration fraction, free-water clearance, and maximal concentrating ability was assessed before and after 15 days of drug. No alterations in any parameter were noted with labetalol. Inulin clearance fell by 13% (p less than 0.05), and filtration fraction fell from 0.23 to 0.18 (p less than 0.02), but other parameters of renal function did not change with methyldopa.

Adult↗
PubMed1977

The glutathione S-transferases of the small intestine in the rat.

Glutathione S-transferase activities have been identified in the small intestine of the rat. Thrree activities obtained with p-nitrobenzyl chloride (aralkyl), 1,2-epoxy-3(p-nitrophenoxy)propane (epoxide), and ethacrynic acid (alkene) as substrates were present in significant amounts. Gel filtration indicated an elution volume for the intestinal transferase activities that was similar to those activities in the liver and kidney. The induction of the intestinal transferases by polycyclic aromatic hydrocarbons and phenobarbital is similar to those effects observed previously for the hepatic and renal enzymes. The highest concentration of transferase activities occurs in the proximal small intestine; these activities are reduced upon fasting. Parallel observations have been reported for aryl hydrocarbon hydroxylases. Because only low or negligible levels of epoxide hydrases have been reported in the small intestine, the glutathione S-transferases may be the primary epoxide-detoxifying system in that organ.

Animals↗
PubMed1976

Comparison of renal and hepatic glutathione S-transferases in the rat.

Renal and hepatic GSH (reduced glutathione) S-transferase were compared with respect to substrate and inhibitory kinetics and hormonal influences in vivo. An example of each of five classes of substrates (aryl, aralkyl, epoxide, alkyl and alkene) was used. In the gel filtration of renal or hepatic cytosol, an identical elution volume was found for all the transferase activities. Close correspondence in Km values was found for aryl, epoxide- and alkyl-transferase activities, with only the aralkyl activity significantly lower in kidney. Probenecid and p-aminohippurate were competitive inhibitors of renal aryl-, aralkyl-, epoxide- and alkyl-transferase activities and inhibited renal alkene activity. Close correspondence in Ki values for inhibition by probenecid of these activities in kidney and liver was found. In addition, furosemide was a potent competitive inhibitor of renal alkyl-transferase activity. Hypophysectomy resulted in significant increases in aryl-, araklyl-, and expoxide-transferase activities in liver and kidney. The hypophysectomy-induced increases in renal aryl- and aralkyl-transferase activities (approx. 100%) were more than twofold greater than increases in hepatic activities (approx. 40%). Administration of thyroxine prevented the hypophysectomy-induced increase in aryltransferase activity in both kidney and liver. The renal GSH S-transferases, in view of similarities to the hepatic activities, may play a role as cytoplasmic organic-anion receptors, as previously proposed for the hepatic enzymes.

Animals↗
PubMed1975

Drug induction of hepatic glutathione S-transferases in male and female rats*.

The induction of the glutathione S-transferases by phenobarbital and polycyclic hydrocarbons was studied in male and female rats. Administration of phenobarbital resulted in 60-80% increase in S-aryl and S-aralkyl enzyme specific activities, whereas the S-epoxide and S-alkyl activities were increased by 30-40%. In following the sequence of induction, the former two activities were noted to reach peak activities before an increase in the latter two activities was observed. Both 3-methylcholanthrene and 3,4-benzopyrene were shown toi nduce these four enzymic activities, although without the discrimination between pairs of activities noted with phenobarbital. No change in Km accompanied the increase in Vmax. after induction by drugs, and no change occurred in Ki for sulphobromophthalein inhibition. Significantly lower enzyme specific activities were found for three of the activities studied in female rats but no difference was observed in the S-alkyltransferase activity. However, the proportional increase in the enzymic activities in response to phenobarbital was the same in males and females. These studies demonstrate the drug induction of a group of cytosolic drug-metabolizing enzymes as well as the identification of sex differences in these activities.

Animals↗
PubMed1975

Drug induction and sex differences of renal glutathione S-transferases in the rat.

Treatment of male rats with 3,4-benzopyrene, 3-methylcholanthrene and phenobarbital resulted in the induction of glutathione S-aryl- and S-aralkyl-transferase activities in kidney cytosol. Benzopyrene produced 77 and 44% increases in aryl and aralkyl activities respectively. Methylcholanthrene caused 73 and 86% increases in the retrospective activities, whereas phenobarbital treatment increased only aralkyl activity (51%). There was no effect on epoxide or alkyl glutathione S-transferase activities with these treatments. Differences were found between the specific activities of the four glutathione S-transferases in females and males, with the following female/male ratios: aryl 0.74; aralkyl 2.37; epoxide 1.52; alkyl 1.33. No changes in Km values were observed relative to drug induction or sex differences. Comparisons are made between the findings of this report and corresponding experiements with liver.

Animals↗
PubMed1975

Hepatic glutathione S-transferases: identification by gel filtration and in vitro inhibition by organic anions.

In the gel filtration of 100,000 g rat liver supernatant, four major glutathione S-transferase activities, S-aryl-, S-epoxide-, S-aralykyl, and S-alkyltransferase, were identified as having an elution volume identical to that of fractions exhibiting either glutathione or sulfobromophthalein sodium binding. The organic anions, sulfobromophthalein sodium, indocyanine green, and bilirubin, were found to be competitive inhibitors of the four glutathione S-transferase activities. These findings indicate that the glutathione S-transferases bind organic anions, and as a group, have a similar molecular weight to a known organic anion-binding protein. It is proposed that these enzymes also serve nonenzymically as a group of binding proteins in the hepatic cytoplasmic transport of organic anions.

Animals↗