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Biomedical subjects

T Barnett

Publications and source records attributed to T Barnett.

At least 19 recordsLinked to original sources
PubMed1996

High-fat diet blocks the inhibition of skin carcinogenesis and reductions in protein kinase C by moderate energy restriction.

The aim of this investigation was to determine the impact of dietary energy restriction (ER) with control (C) and high-fat (HF) diets on two-stage skin carcinogenesis and on the expression of specific isoforms of protein kinase C (PKC). Skin carcinogenesis was initiated on SENCAR mice with 10 nmol of 7,12-dimethylbenz[a]anthracene (DMBA) in 0.2 mL of acetone and then promoted with twice weekly treatments of 3.2 nmol of 12-O-tetradecanoylphorbol-13-acetate (TPA) in 0.2 mL of acetone for 18 wk. The experimental diets fed during TPA treatment and for 10 wk after the last TPA treatment were formulated with C (10% calories from fat) and HF (42% calories from fat) levels for freely fed groups. These diets were restricted by 20% (20% ER/C and 20% ER/HF) and by 40% (40% ER/C and 40% ER/HF). Papilloma incidence was reduced in the mice fed the 20% ER/C, 40% ER/C, and 40% ER/HF diets in comparison with the C, HF, and 20% ER/HF groups. Carcinoma incidence was also reduced in these groups. PKC alpha and zeta were assessed by western blot analysis in the epidermises of mice pre-fed the six diets for 8-10 wk (without DMBA or TPA treatment). PKC alpha was reduced in the particulate fraction by 32-44% in the 20% ER/C, 40% ER/C, and 40% ER/HF groups (P < 0.005). PKC zeta was reduced by 24-31% in the cytosol of mice fed the 20% ER/C diet and in the particulate fraction of mice fed the 40% ER/C diet (P < 0.05). The HF diet was able to block the inhibition of skin carcinogenesis and the reduction in the expression of PKC in the epidermis by 20% ER but not by 40% ER.

Animals↗
PubMed1996

Proton MR spectroscopy of the basal ganglia in healthy children and children with AIDS.

PURPOSE: To evaluate proton magnetic resonance (MR) spectroscopy in children with the acquired immunodeficiency syndrome (AIDS) and to establish an age-dependent spectroscopic database of the normal basal ganglia in children. MATERIALS AND METHODS: Eighteen healthy children and 45 children with AIDS underwent both brain MR imaging and single-voxel MR spectroscopy with a long-echo-time point-resolved technique. A large part of the region of interest studied at MR spectroscopy included the basal ganglia. RESULTS: Seven patients with progressive encephalopathy and eight with static encephalopathy had significantly lower mean N-acetyl aspartate (NAA)/creatine (Cr) ratios than age-matched control subjects (P<.02). In determining the presence of progressive encephalopathy in children with AIDS, MR spectroscopy appears to be more sensitive and specific than MR imaging and immunologic testing. Thirty patients without encephalopathy had normal NAA/Cr ratios but significantly lower choline/Cr ratios than age-matched control subjects (P<.02). CONCLUSION: Proton MR spectroscopy may be a more sensitive diagnostic technique than MR imaging in childhood AIDS encephalopathy.

AIDS Dementia Complex↗
PubMed1996

High-dose therapy followed by autologous hematopoietic stem-cell infusion for patients with multiple myeloma.

PURPOSE: To evaluate the outcome of patients with multiple myeloma (MM) who received high-dose therapy followed by autologous bone marrow (BM) or peripheral-blood stem-cell (PBSC) infusion. PATIENTS AND METHODS: Sixty-three consecutive patients with MM received autologous BM (n = 13) or PBSC with or without BM (n = 50) following regimens that contained busulfan (Bu) and cyclophosphamide (Cy) (n = 18), modified total-body irradiation (TBI) followed by Bu and Cy (n = 36), or Bu, melphalan, and thiotepa (n = 9). Two thirds of the patients had resistant disease and 69% had received more than 6 months of previous chemotherapy. RESULTS AND CONCLUSION: Recovery of peripheral-blood cell counts was more rapid in patients who received PBSC with or without BM than in patients who received BM alone. Sixteen of 63 patients (25%) died of complications of treatment within 100 days. Nineteen (40%) of 48 assessable patients achieved a complete response (CR), 23 (48%) had a partial response (PR), and six (12%) had no response. The probabilities of survival and survival without relapse or progression for all 63 patients at 3.0 years were .43 and .21, respectively. The probability of relapse or progression at 3 years was .69, and 17 patients (27%) have died of progressive MM. The probabilities of survival and relapse-free survival at 3 years for the 19 patients who achieved a CR were .42 and .17, respectively. In the multivariate analysis, beta2-microglobulin levels more than 2.5 micrograms/mL, more than two regimens of prior therapy and eight cycles of treatment, time to transplant longer than 3 years from diagnosis, and prior radiation were associated with adverse outcomes. Additional strategies, such as intervention earlier in the disease course, improved treatment regimens, sequential high-dose treatments, and posttransplant therapies may improve outcome of selected patients with MM.

Adult↗
PubMed1995

Coeur en santé St-Henri--a heart health promotion programme in Montreal, Canada: design and methods for evaluation.

STUDY OBJECTIVE: This paper describes the objectives, design, and methods of evaluation of the impact of the coeur en santé St-Henri programme, as well as selected results from the evaluation to date. It discusses the possible effects of study design choices made to maintain the impact evaluation within budget. DESIGN: The impact of the programme is evaluated in a community trial which compares the prevalence of cardiovascular disease behavioural risk factors before and after programme implementation in the intervention and a matched comparison community, in both longitudinal cohort and independent sample surveys. In addition, repeated independent sample surveys are conducted in the intervention community to monitor awareness of and participation in the programme. PARTICIPANTS: The baseline sample for both the longitudinal cohort and independent sample surveys included 849 subjects from the intervention community (79.3% of 1071 eligible subjects--8.0% could not be contacted and 12.6% refused) and 825 subjects from the comparison community (77.8% of 1066 eligible subjects--6.6% could not be contacted and 15.6% refused). The two surveys on awareness and participation conducted to date, included 461 (71.0% of 649 eligible subjects) and 387 (67.9% of 570 eligible subjects) subjects respectively from the intervention community. MEASUREMENTS: Baseline data for the longitudinal cohort and independent sample surveys on behavioural risk factor outcomes including use of tobacco, physical activity behaviour, high fat diet, and behaviours related to blood pressure and cholesterol control were collected in 35 minute telephone interviews in both the intervention and comparison communities. Data on awareness of and participation in the programme were collected in 10 minute interviews in the intervention community only in two independent sample surveys conducted seven and 22 months respectively after the baseline survey. RESULTS: With the exception of smoking, the intervention and comparison communities were similar at baseline with regard to the prevalence of behavioural risk factors studied. Awareness of the coeur en santé programme increased from 64.1% in January 1993 to 72.9% 15 months later. Participation in the programme increased from 21.3% to 33.7%. CONCLUSIONS: This paper presents background information on the evaluation of the impact of the coeur en santé programme, as a reference for future publications.

Adolescent↗
PubMed1994

Consumption of reduced-energy/low-fat diet or constant-energy/high-fat diet during mezerein treatment inhibited mouse skin tumor promotion.

Previous studies in our laboratory have shown that promotion of two-stage skin carcinogenesis in the SENCAR mouse model was inhibited in mice fed energy-restricted/low-fat diets, and elevated in mice fed high-fat diets. Studies reported here describe the influence of dietary energy restriction from fat and carbohydrate (ER) or high-fat (HF) diet on early promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA) and on late promotion by mezerein (MEZ). Female SENCAR mice were initiated topically with 10 nmol 7,12-dimethylbenz[a]anthracene (DMBA) in 0.2 ml acetone at 9 weeks of age. For the following 2 weeks they received 3.2 nmol TPA in 0.2 ml acetone twice weekly, and for the next 16 weeks they received 10 nmol MEZ in 0.2 ml acetone twice weekly. All mice were fed control diet before TPA began and following the final MEZ treatment. Control mice received the control diet (c) throughout TPA and MEZ (C/C). The six experimental groups received: (1) ER diet throughout TPA and MEZ treatment (ER/ER); (2) HF diet throughout TPA and MEZ treatment (HF/HF); (3) ER during TPA (ER/C); (4) ER during MEZ (C/ER); (5) HF diet during TPA (HF/C); or (6) HF diet during MEZ (C/HF). Papilloma incidence and multiplicity, and carcinoma incidence were similarly reduced in the mice fed ER diet during MEZ (ER/ER and C/ER groups). In comparing the HF groups, papilloma multiplicity was highest in the HF/C group, intermediate in the C/C and lowest in the C/HF groups, but papilloma and carcinoma incidences were not modified by the HF diet protocols. Papilloma regression was greater in the C/HF group (27%, 4 regressions/15 tumor-bearing mice) than in the controls (0/18) during weeks 21-23, immediately following the end of MEZ treatment (P < 0.05).

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Protein kinase C activity is reduced in epidermal cells from energy-restricted SENCAR mice.

Female SENCAR mice were pre-fed a control or 40% energy-restricted (ER) diet with energy removed from fat and carbohydrate, or a control, balanced high fat (BHF, with similar energy from fat and carbohydrate), 35% energy restricted from fat (HCR) or 35% energy restricted from carbohydrate (HFR) diet. Epidermal cells were isolated by trypsin digestion for measurement of protein kinase C (PKC) activity, lipid composition or lipid metabolism. Dietary restriction of fat or carbohydrate energy (HFR or HCR group) reduced particulate PKC activity in epidermal cells compared with cells from control mice. The ratio of soluble particulate PKC activity was higher in epidermal cells from mice fed the HCR diet compared with those fed the HFR diet. Diet did not affect soluble PKC activity. Inositol accumulation was measured in the water- or lipid-soluble fractions of prelabeled ([3H]inositol) epidermal cells following a 1-h incubation in media with LiCl. Phosphatidylinositol, inositol biphosphate and inositol triphosphate fractions were more heavily labeled in cells from mice fed the ER diet. Energy restriction did not modify epidermal total lipid or phospholipid composition, but 1,2-diacylglycerol levels were elevated in relation to cell number in epidermal cells from mice fed the ER diet. These data suggest that dietary energy restriction modified PKC activity through a pathway other than alteration in membrane lipid composition or inositol lipid metabolism.

Animals↗
PubMed1993

A revised structure for fucoidan may explain some of its biological activities.

Fucoidan from Fucus vesiculosus inhibits human sperm-zona pellucida binding and blocks the zona pellucida-induced acrosome reaction in human sperm. Fucoidan also potently inhibits selectin-mediated adhesion of leukocytes to vascular endothelium. To understand the molecular basis for fucoidan's inhibition of specific cell adhesion events, we have investigated the structure of this fucan using definitive methods of carbohydrate structural analysis. We report the revised average structure for fucoidan. [formula: see text] This average structure differs from the previous model for fucoidan in two respects. First, the core region of the fucan is composed primarily of a polymer of alpha 1-3-linked fucose with sulfate groups substituted at the 4 position on some of the fucose residues. Secondly, fucose is also attached to this polymer to form branch points, one for every 2-3 fucose residues within the chain. This revised average structure is consistent with previous studies suggesting a branched random coil as the best model for this polysaccharide. The proposed model is also a closer structural analogue of the sulfated carbohydrate ligands that bind to selectins. This information should be useful for determining whether a relationship exists between selectin-mediated adhesion of leukocytes and human sperm-egg binding.

Carbohydrate Conformation↗
PubMed1993

Inhibition of skin tumor promotion by restriction of fat and carbohydrate calories in SENCAR mice.

The purpose of this research was to compare the influence of calorie restriction by removal of fat with calorie restriction by removal of carbohydrate on the promotion of skin tumorigenesis in mice. Female SENCAR mice were initiated with 7,12-dimethylbenz(a)anthracene (10 nmol, single topical treatment) and fed calorie-restricted diets during and following promotion with 12-O-tetradecanoylphorbol-13-acetate (2 micrograms, topically, twice a week for 20 weeks). Control diet (American Institute of Nutrition-based formulation) was compared with a diet in which calories from fat and calories from carbohydrate were similar [balanced high fat (BHF)] in ad libitum-fed groups. Restricted animals were fed diets such that 35% of the calories from fat [high carbohydrate, calories restricted from fat (HCR)] or from carbohydrate (high fat, calories restricted from carbohydrate) were restricted, but other intake was equivalent to the BHF group. Results showed an inhibition of papilloma number in both restricted groups and the inhibition was greatest in the HCR mice. Larger papillomas were observed on mice in the control, BHF, and high-fat, calories restricted from carbohydrate diet groups than on mice in the HCR group. The pattern of carcinoma development was similar in the mice in the freely fed control and BHF groups. Restriction of calories from either fat or carbohydrate delayed the rate and reduced the incidence of carcinoma development. Carcinoma incidence did not differ between mice fed the high-fat, calories restricted from carbohydrate and HCR diets.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Polyglycosylceramides with branched N-acetyllactosamine sequences are synthesized by the human pancreatic carcinoma cell line PANC-1.

We have metabolically labeled the human pancreatic tumor cell line PANC-1 with high specific activity tritiated sugar precursors to study the expression of glycosphingolipids by this cell type. We have used a combination of detergent solubilization, exhaustive protease digestion, ceramide glycanase digestion, and reverse-phase chromatography to isolate glycosphingolipid-derived oligosaccharides specifically labeled in their component sugars. A significant proportion of the oligosaccharides derived from polar glycosphingolipids were of high molecular mass (greater than 2000 Da). The results of compositional studies, lectin affinity chromatography, and methylation analysis suggested that this high molecular weight fraction consists of lactosaminoglycan type oligosaccharides derived from polyglycosylceramides. There are on average three beta 1-6 linked N-acetyllactosamine branches attached to the polylactosamine backbone in this type of glycosphingolipid-derived oligosaccharide. The majority of the oligosaccharides also contain 1-2 mol of sialic acid that are linked alpha 2-3 to penultimate galactose. The results indicate that PANC-1 cells, like human colorectal tumor cells, express highly extended neolacto type glycosphingolipids. However, the lactosaminoglycan sequences are highly branched, unlike those associated with colorectal tumor cells.

Amino Sugars↗
PubMed1992

Influences of sphingosine on two-stage skin tumorigenesis in Sencar mice.

Sphingosine (SPH) was studied as an inhibitor of skin tumor promotion in skin cancer initiated by 7,12-dimethylbenz[a]-anthracene (DMBA) and promoted by 12-O-tetradecanoylphorbol-13-acetate (TPA). Two tumorigenesis studies were conducted using female Sencar mice treated with 10 nmol DMBA in 0.2 ml acetone at 8 weeks of age and promoted beginning 1 week later with 3.2 nmol TPA applied twice per week. In the high-dose study, 10 mumol SPH was applied 30 min before each TPA treatment. The low-dose study used 0.5, 0.05, or 0.01 mumol treatments with SPH 30 min before TPA. In the high-dose study SPH treatment alone following initiation by DMBA, and SPH treatment preceding TPA in DMBA-initiated mice accelerated the development of papillomas in comparison with the DMBA/TPA-treated group. The low-dose experiment showed no consistent alteration of tumorigenesis by SPH in the DMBA/TPA-treated groups, and low doses of SPH following DMBA did not promote skin tumorigenesis. SPH treatment did not alter body weight in either experiment.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Soft drink consumption and urinary stone recurrence: a randomized prevention trial.

The object of this study was to determine if a strong association between soft drink (soda) consumption and recurrence of urinary stone disease, found in an earlier case-control study of adult males, had a causal component. The study sample consisted of 1009 male subjects, who completed an episode of urinary stone disease, who were aged 18-75 at that time, and who reported consuming at least 160 ml per day of soft drinks. Half of the subjects were randomized to refrain from consuming soft drinks, while the remaining subjects served as controls. The intervention group had an observed 6.4% advantage in actuarial 3 yr freedom from recurrence (p = 0.023 one-sided) over the control group. One important secondary finding was that for those who reported at the time of the index stone that their most consumed drink was acidified by phosphoric acid but not citric acid, the experimental group had a 15% higher 3 yr recurrence-free rate than the controls, p = 0.002, while for those who reported at the time of the index stone that their most consumed drink was acidified by citric acid with or without phosphoric acid, the experimental group had a similar 3 yr recurrence-free rate to the controls, p = 0.55. This interaction was significant, p = 0.019.

Actuarial Analysis↗
PubMed1992

Clinical improvement of the myopathy in eosinophilia-myalgia syndrome with steroids and rehabilitative therapy.

The authors report a case of eosinophilia-myalgia syndrome with a progressive neuromyopathy. Progressive weakness, myalgia, and dermatitis developed in the patient described after chronic ingestion of high-dose L-tryptophan for insomnia. Laboratory, electrophysiologic, and muscle biopsy results support the diagnosis of an inflammatory myopathy consistent with that of eosinophilia-myalgia syndrome. The patient's weakness led to wheelchair dependency. A review of the literature regarding this disorder shows inconsistent results with steroid and other modes of therapy. After a course of high-dose steroids with long-term tapering and vigorous inpatient and outpatient rehabilitation, the patient was able to walk and function independently within 2 months.

Adult↗
PubMed1992

A useful modification of cDNA that enhances purification of recombinant protein.

With the availability of new and improved DNA vectors for producing large amounts of proteins by recombinant DNA technology, there is a growing need for efficient recovery of the desired protein, often from liters of culture medium. In this report, we describe a relatively simple modification of recombinant cDNA, that, in combination with immobilized metal affinity chromatography, is a rapid, inexpensive and highly effective method for enriching or purifying a desired protein.

Base Sequence↗
PubMed1991

Influence of diet and calorie restriction on the initiation and promotion of skin carcinogenesis in the SENCAR mouse model.

Diets were restricted to 60% of the intake of the control mice by feeding less diet (total diet restriction, TDR) or by feeding fewer calories from fat and carbohydrate (calorie restriction, CR) during the initiation or promotion phases of skin tumorigenesis in female SENCAR mice. Skin cancer was initiated by topical treatment with 10 nmol of 7,12-dimethylbenzanthracene in acetone and promoted by twice weekly treatments with 12-O-tetradecanoylphorbol-13-acetate in acetone for 20 wk. Dietary restriction preceding and during 7,12-dimethylbenzanthracene treatment did not influence skin papilloma or carcinoma yield. Papilloma incidence and the number of papillomas per effective mouse were reduced in mice restricted by both TDR and CR protocols during and following promotion with 12-O-tetradecanoylphorbol-13-acetate. Papilloma size was reduced at experimental wk 16 and 20 in both TDR and CR groups fed these diet regimens during promotion. However, by wk 28 and 32, papilloma sizes were similar in the control and TDR groups, and smaller papillomas were observed only in the CR group. The average carcinoma latency was extended by 26% in the groups restricted during promotion, and incidence was reduced in both groups. The reduction, however, was statistically significant only in the CR group. Body weight gain was reduced during the times when dietary restriction was enforced, and in a short-term study, both restricted diet treatments reduced the percentage of carcass protein.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Extracorporeal shock wave lithotripsy in a renal transplant patient.

We report a case of nephrolithiasis in a transplanted kidney that was treated successfully with extracorporeal shock wave lithotripsy. The patient experienced transient partial obstruction after lithotripsy and, thus, intense monitoring of the transplant patient is necessary.

Adolescent↗
PubMed1988

Carcinoembryonic antigen family: characterization of cDNAs coding for NCA and CEA and suggestion of nonrandom sequence variation in their conserved loop-domains.

We have isolated cDNAs for carcinoembryonic antigen (CEA) and for a normal cross-reacting antigen (NCA) and report here their nucleotide and derived amino acid sequences. Our data show that both the CEA and NCA polypeptides are organized into extracellular domains, some with cysteine-linked loops, that share extensive sequence homology (approximately 78% overall) with each other and appear similar to immunoglobulin superfamily members. A major difference between the two apoproteins is the presence of a single loop-domain in NCA compared to three tandemly repeated loop-domains in CEA. Sequence comparisons between the extracellular domains of CEA and NCA show that the N-terminal and adjacent loop domains of each apoprotein have high homology (85-90%) to each other, while comparison of loop-domain regions reveals a possible nonrandom distribution of base changes and altered amino acids near certain cysteine residues that are inferred to be involved in forming disulfide loops. Both apoproteins show high identity in their hydrophobic C-termini that are reminiscent of the type of transmembrane tails seen in proteins that potentiate signal transduction. These findings, coupled with distinct expression profiles of CEA and NCA mRNAs, suggest that these apoproteins may function as unique cell-surface molecules mediating cell-specific interactions in normal and neoplastic cells.

Amino Acid Sequence↗