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J P Simons

Publications and source records attributed to J P Simons.

At least 19 recordsLinked to original sources
PubMed2001

Structural diversity despite strong evolutionary conservation in the 5'-untranslated region of the P-type dystrophin transcript.

Analysis of the 5'-flanking regions of the Purkinje (P-) dystrophin genes and mRNAs in different species revealed strong sequence conservation but functional diversity. Multiple transcription initiation sites were identified in cerebella and muscles, tissues expressing P-dystrophin. The predominant initiation site was conserved, with another muscle-specific site located upstream. Despite sequence homology, significant tissue- and species-specific structural diversity in the P-type 5'-ends exists, including alternative splicing within the 5'-untranslated region combined with alternative splicing of intron 1. One amino terminus is conserved in mammals and, to a lesser extent, in chicken. However, alternative usage of ATG codons may result in a choice of N-termini or translation of short upstream ORFs in different species. Promoter activity of a fragment upstream of the cap site was shown by transient expression in myoblasts and in vivo following intramuscular injection. It is tissue- and developmentally regulated. Analysis of promoter deletions suggests the existence of negative regulatory elements in the proximal region.

5' Untranslated Regions↗
PubMed2001

Expression of the Ror1 and Ror2 receptor tyrosine kinase genes during mouse development.

Ror1 and Ror2 are orphan receptor tyrosine kinases that are most closely related to MuSK and the Trk family of neurotrophin receptors. We report the results of an extensive in situ hybridisation survey of the expression of these genes during mouse development. Expression of Ror1 and Ror2 differs markedly at early stages (E8.5--E9.5). At these times, Ror2 is expressed much more widely than Ror1, expression of which is largely restricted to head mesenchyme. At later stages of development (E12.5--E14.5), Ror1 expression expands and Ror2 expression becomes more restricted than at earlier times, although expression of Ror1 continues to be more restricted than that of Ror2. These changes result in overlapping expression domains but with major differences remaining. In many cases Ror1 is expressed in a sub-set of Ror2-expressing tissues; in others, there is complementary expression of Ror1 and Ror2. Ror1 and Ror2 are both expressed in derivatives of all three germ layers and in most organ systems, including the nervous, circulatory, respiratory, digestive, urogenital and skeletal systems. Conspicuous themes are the expression in major sense organs, and in neural crest and its derivatives.

Animals↗
PubMed2001

The role of topical antibiotic prophylaxis in patients undergoing contaminated head and neck surgery with flap reconstruction.

OBJECTIVES/HYPOTHESIS: Patients undergoing contaminated head and neck surgery with flap reconstruction have wound infection rates of 20% to 25% with parenteral antibiotic prophylaxis. Studies suggest that perioperative antimicrobial mouthwash reduces oropharyngeal flora and may prevent wound infections. We hypothesized that the addition of topical antibiotics to a parenteral prophylactic regimen would reduce the incidence of wound infection in these high-risk patients. STUDY DESIGN: We performed a randomized, prospective clinical trial. METHODS: Patients received either 1) parenteral piperacillin/tazobactam (3.375 g every 6 hours for 48 h) or 2) parenteral piperacillin/tazobactam plus topical piperacillin/tazobactam administered as a mouthwash immediately before surgery and once a day for 2 days postoperatively, with piperacillin/tazobactam added to the intraoperative irrigation solution. The wounds of all patients were evaluated daily using predefined objective criteria. RESULTS: Sixty-two patients met inclusion criteria and were enrolled in the study. The overall wound infection rate was 8.1% (95% confidence interval [CI], 2.7%-17.8%). Two of 31 patients (6.4%) who received parenteral antibiotics alone developed a wound infection compared with 3 of 31 patients (9.7%) randomly assigned to receive topical plus parenteral antibiotics. This difference was not statistically significant (P = >.05). Infection rate was not associated with flap type (rotational vs. free tissue transfer), mandibular reconstruction, age, gender, tumor site, stage, surgical duration, or blood loss. CONCLUSIONS: These results suggest that piperacillin/tazobactam is a highly effective antibiotic for prevention of wound infection in patients undergoing flap reconstruction following contaminated head and neck surgery. However, the addition of topical piperacillin/tazobactam does not appear to enhance the prophylactic benefit of parenteral antibiotics alone.

Administration, Topical↗
PubMed1999

Bioelectrical impedance analysis to assess changes in total body water in patients with cancer.

Predominantly based on studies in obese individuals, the applicability of single-frequency bioelectrical impedance analysis (BIA) to measure changes in total body water and fat-free mass has been questioned. To further clarify this issue, we compared changes in BIA-derived height(2)/resistance (ht(2)/R) with changes in total body water (deuterium dilution, delta-TBWdeu) in cancer patients participating in a clinical trial. Thirty-three patients (mean body mass index 23.2 +/- 3.5 kg/m(2)) were studied after an average follow-up of 11 weeks. Changes in TBWdeu occurred in both directions (mean +0.2 +/- 1.6 L, range -3.3 to +3.1 L). These changes were significantly predicted by changes in ht(2)/R (r(2)0.43, P < 0.0001, SEE 1.22 L), although precision was poor (residual SD 1. 2 L). There were in this regard no significant differences between patients with and without underweight. We conclude that in underweight and normal-weight cancer patients, BIA-derived changes in ht(2)/R significantly predict changes in total body water assessed by deuterium dilution.

Adipose Tissue↗
PubMed1999

Weight loss and low body cell mass in males with lung cancer: relationship with systemic inflammation, acute-phase response, resting energy expenditure, and catabolic and anabolic hormones.

The aim of the present study was to investigate, in human lung cancer, the relationship between weight loss and the existence of a low body cell mass (BCM) on the one hand, and the putative presence of systemic inflammation, an increased acute-phase response, anorexia, hypermetabolism and changes in circulating levels of several anabolic and catabolic hormones on the other. In 20 male lung cancer patients, pre-stratified by weight loss of >/=10% (n=10) or of <10% (n=10), the following measurements were performed: BCM (by dual-energy X-ray absorptiometry/bromide dilution), circulating levels of sTNF-R55 and sTNF-R75 (soluble tumour necrosis factor receptors of molecular masses 55 and 75 kDa respectively), interleukin-6, lipopolysaccharide-binding protein, albumin, appetite (scale of 0-10), resting energy expenditure (by indirect calorimetry) and circulating levels of catabolic (cortisol) and anabolic [testosterone, insulin-like growth factor-I (IGF-I)] hormones. Compared with the patients with a weight loss of <10%, those with a weight loss of >/=10% were characterized by higher levels of sTNF-R55 (trend towards significance; P=0.06), and lower levels of albumin (27.4 compared with 34.4 mmol/l; P=0.02), testosterone (13.2 compared with 21.5 nmol/l; P=0.01) and IGF-I (119 compared with 184 ng/ml; P=0.004). In the patient group as a whole, the percentage weight loss was significantly correlated with sTNF-R55 (r=0.59, P=0.02), albumin (r=-0.63, P=0.006) and IGF-I (r=-0.50, P=0.02) levels. Height-adjusted BCM was significantly correlated with sTNF-R55 (r=-0.57, P=0.03), sTNF-R75 (r=-0.50, P=0. 04), lipopolysaccharide-binding protein (r=-0.50, P=0.04), albumin (r=0.56, P=0.02) and resting energy expenditure/BCM (r=-0.54, P=0. 03), and there was a trend towards a correlation with IGF-I concentration (r=0.44, P=0.06). We conclude that, in human lung cancer, weight loss and the presence of a low BCM are associated with systemic inflammation, an increased acute-phase response and decreased levels of IGF-I. In addition, a decreased BCM is associated with hypermetabolism.

Acute-Phase Proteins↗
PubMed1998

Effects of medroxyprogesterone acetate on food intake, body composition, and resting energy expenditure in patients with advanced, nonhormone-sensitive cancer: a randomized, placebo-controlled trial.

BACKGROUND: Anorexia and cachexia are well-known sequelae of cancer that contribute to morbidity and mortality. In several studies in patients with non-hormone-sensitive tumors, synthetic progestogens were shown to exert beneficial effects on appetite and weight loss. The current study was undertaken to investigate the effects of medroxyprogesterone acetate (MPA) on food intake, body composition, and resting energy expenditure (REE). METHODS: Fifty-four patients with non-hormone-sensitive cancer, generally characterized by substantial weight loss and hypermetabolism, received either MPA, 500 mg, or placebo twice daily for 12 weeks (double-blind study). Food intake was measured by dietary history, body composition was assessed by deuterium dilution (fat mass, fat-free mass), and REE was obtained by indirect calorimetry. RESULTS: Compared with placebo, 12 weeks of MPA led to an increase in energy intake (between-group difference, 426 kcal/day; P = 0.01) that was significantly associated (r = 0.68, P = 0.003) with an increase in fat mass (between-group difference, 2.5 kg; P = 0.009). Fat-free mass was not significantly influenced. REE increased during MPA treatment: at 6 weeks, the between-group difference in change was 135 kcal/day (P = 0.009); after 12 weeks, this difference was 93 kcal/ day (P = 0.07). CONCLUSIONS: The authors conclude that MPA is able to stimulate increased food intake significantly and to reverse fat loss concomitantly in patients with non-hormone-sensitive cancer.

Aged↗
PubMed1997

Plasma concentration of total leptin and human lung-cancer-associated cachexia.

1. Adipocyte-derived leptin is postulated to represent the afferent hormonal signal to the hypothalamus in a feedback mechanism that regulates fat mass. In this proposed feedback mechanism, increased fat mass leads to an elevated plasma leptin level that eventually induces a decrease in appetite and an increase in energy expenditure, and vice versa. 2. As anorexia and hypermetabolism play a role in the development of cancer cachexia, we investigated the hypothesis that underlying abnormalities in the leptin feedback mechanism (in particular relatively high plasma leptin levels or, on the other hand, a hypothalamic insensitivity to a fall in leptin levels) might be involved. For this purpose, total plasma leptin, body composition (fat mass and fat-free mass), appetite and resting energy expenditure were assessed in 21 male lung-cancer patients. 3. Total leptin was detectable in six patients and non-detectable in 15. In comparison with the latter, the patients with detectable leptin were characterized by a trend towards less weight loss (3.4% compared with 11.0%, P = 0.07), as being less underweight (body mass index 23.8 kg/m2 compared with 19.4 kg/m2, P = 0.004) and by a higher fat mass (21.4 kg compared with 9.7 kg, P = 0.001). Significant between-group differences in appetite and resting energy expenditure were lacking. 4. Based on these findings, we conclude that in cancer the afferent part of the leptin feedback mechanism functions normally and that, in particular, elevated leptin levels are not involved in the development of cachexia. Since the absence of plasma leptin was not associated with an increased appetite and decreased energy expenditure, disturbances in the hypothalamic part of the feedback mechanism are hypothesized.

Aged↗
PubMed1997

Processing of DNA prior to illegitimate recombination in mouse cells.

In mammalian cells, the predominant pathway of chromosomal integration of exogenous DNA is random or illegitimate recombination; integration by homologous recombination is infrequent. Homologous recombination is initiated at double-strand DNA breaks which have been acted on by single-strand exonuclease. To further characterize the relationship between illegitimate and homologous recombination, we have investigated whether illegitimate recombination is also preceded by exonuclease digestion. Heteroduplex DNAs which included strand-specific restriction markers at each of four positions were generated. These DNAs were introduced into mouse embryonic stem cells, and stably transformed clones were isolated and analyzed to determine whether there was any strand bias in the retention of restriction markers with respect to their positions. Some of the mismatches appear to have been resolved by mismatch repair. Very significant strand bias was observed in the retention of restriction markers, and there was polarity of marker retention between adjacent positions. We conclude that DNA is frequently subjected to 5'-->3' exonuclease digestion prior to integration by illegitimate recombination and that the length of DNA removed by exonuclease digestion can be extensive. We also provide evidence which suggests that frequent but less extensive 3'-->5' exonuclease processing also occurs.

Animals↗
PubMed1996

Hormonal treatment in advanced non-small cell lung cancer: fact or fiction?

In patients with advanced non-small cell lung cancer, cachexia is an important cause of morbidity and mortality. The pathogenic mechanism of this finding, usually referred to as "cancer anorexia and cachexia syndrome" (CACS), is complex and far from completely understood, but a disturbed equilibrium between possible food intake and metabolic needs seems to be fundamental. The literature data on the treatment options in advanced non-small cell lung cancer (NSCLC) with cachexia are reviewed. Based on the clinical studies on cancer cachexia, some recommendations for the therapeutic approach of this disorder in patients with advanced NSCLC can be given. Metoclopramide is easily administered, can alleviate gastric disturbances, but probably does not correct the catabolic spiral of CACS. There are not enough data to advise the use of parenteral nutritional support, hydrazine, cyproheptadine, tetrahydrocannabinol or nandrolone decanoate. Corticosteroids are useful in additional analgesia and fast palliation of very weak and debilitated patients in the final episode of their disease. Recent data in non-small cell lung cancer patients are in favour of the use of high-dose progestagens to improve both appetite and weight.

Cachexia↗
PubMed1996

Effects of medroxyprogesterone acetate on appetite, weight, and quality of life in advanced-stage non-hormone-sensitive cancer: a placebo-controlled multicenter study.

PURPOSE: To investigate the effects of medroxyprogesterone acetate (MPA) on appetite, weight, and quality of life (QL) in patients with advanced-stage, incurable, non-hormone-sensitive cancer. PATIENTS AND METHODS: Two hundred six eligible patients were randomized between double-blind MPA 500 mg twice daily or placebo. Appetite (0 to 10 numerical rating scale), weight, and QL (European Organization for Research and Treatment of Cancer Quality of Life Questionnaire [EORTC-QLQ-C30]) were assessed before the start of treatment (t = 0), and 6 weeks (t = 6) and 12 weeks (t = 12) thereafter. RESULTS: One hundred thirty-four patients (68 MPA and 66 placebo) were assessable at t = 6 and 99 patients (53 MPA and 46 placebo) at t = 12. A beneficial effect of MPA on appetite was observed after both 6 weeks (P = .008) and 12 weeks (P = .01) of treatment. After 12 weeks, a mean weight gain of 0.6 +/- 4.4 kg was seen in the MPA, versus an ongoing mean weight loss of 1.4 +/- 4.6 kg in the placebo group. This difference of 2.0 kg was statistically significant (P = .04). During the study, several areas of QL deteriorated in the total group of patients. With the exception of an improvement in appetite and possible also a reduction in nausea and vomiting, no measurable beneficial effects of MPA on QL could be demonstrated. The side effects profile of MPA was favorable: only a trend toward an increase in (usually mild) peripheral edema was observed. CONCLUSION: In weight-losing, advanced-stage non-hormone-sensitive cancer patients, MPA exhibits a mild side effects profile, has a beneficial effect on appetite, and may prevent further weight loss. However, general QL in the present study was not measurably influenced by MPA treatment.

Analysis of Variance↗
PubMed1995

The use of bioelectrical impedance analysis to predict total body water in patients with cancer cachexia.

The applicability of bioelectrical impedance analysis (BIA) to predict total body water (TBW) was assessed in 16 underweight [< 95% of ideal body weight (IBW)] and 25 normal-weight (> 95% of IBW) cancer patients. Although height2/resistance (ht2/R) proved to be a strong single predictor of TBW measured by deuterium dilution in both groups (normal-weight patients: r2 = 0.85, SEE 2.16 L; underweight patients: r2 = 0.86, SEE 2.24 L), TBW would be significantly overestimated in the underweight group if the prediction formula developed in the normal-weight group was used [bias 1.67 L (5%), 95% CI 0.20-3.15 L]. A systematic overestimation of TBW in the underweight patients was also found when TBW was predicted in our two patient groups by several previously published BIA formulas developed in normal-weight individuals. We conclude therefore, that although a similar relationship is found between ht2/R and TBW in normal-weight and underweight cancer patients, single-frequency BIA overestimates TBW in underweight patients when prediction formulas are used that have been developed in normal-weight subjects.

Adenocarcinoma↗
PubMed1994

Milk composition and lactation of beta-casein-deficient mice.

beta-Casein is a major protein component of milk and, in conjunction with the other caseins, it is assembled into micelles. The casein micelles determine many of the physical characteristics of milk, which are important for stability during storage and for milk-processing properties. There is evidence that suggests that beta-casein may also possess other, nonnutritional functions. To address the function of beta-casein, the mouse beta-casein gene was disrupted by gene targeting in embryonic stem cells. Homozygous beta-casein mutant mice are viable and fertile; females can lactate and successfully rear young. beta-Casein was expressed at a reduced level in heterozygotes and was completely absent from the milk of homozygous mutant mice. Despite the deficiency of beta-casein, casein micelles were assembled in heterozygous and homozygous mutants, albeit with reduced diameters. The absence of beta-casein expression was reflected in a reduced total protein concentration in milk, although this was partially compensated for by an increased concentration of other proteins. The growth of pups feeding on the milk of homozygous mutants was reduced relative to those feeding on the milk of wild-type mice. Various genetic manipulations of caseins have been proposed for the qualitative improvement of cow's milk composition. The results presented here demonstrate that beta-casein has no essential function and that the casein micelle is remarkably tolerant of changes in composition.

Animals↗
PubMed1993

The effects of terminal heterologies on gene targeting by insertion vectors in embryonic stem cells.

We have examined the effects of placing nonhomologous DNA on the ends of an insertion-type gene targeting vector. The presence of terminal heterologies was found to be compatible with insertion targeting, and the terminal heterologies were efficiently removed. Terminal heterologies reduced the frequency of gene targeting to variable extents. The degree of inhibition of targeting was dependent on the length and the position of the heterology: 2.1kb heterologous sequences were more inhibitory than shorter regions of heterology, and heterology placed on the end of the long (4.8kb) arm of homology was more inhibitory than heterology positioned on the end of the short (0.8kb) arm. When heterology was placed on both arms of the targeting vector the targeting efficiencies were similar to or higher than when heterology was present on the long arm only. These results suggest that terminal sequences are removed simultaneously from both ends of targeting vectors. The removal of terminal sequences probably occurs by exonucleolytic degradation of both strands at each end, and removal of at least one of the strands is intimately coupled with the process of homologous recombination. These findings have implications for the design of gene targeting vectors.

Animals↗
PubMed1993

Enhancing the efficiency of transgene expression.

Two strategies for enhancing gene expression in transgenic animals are described with particular reference to targeting expression to the mammary gland. Gene constructs in which the protein-encoding DNA sequences are contained within a genomic segment (comprising most or all of the natural introns of the corresponding gene) are shown to be expressed more efficiently than their intronless counterparts. Secondly, co-integrating an otherwise poorly expressed transgene in the vicinity of an actively expressed transgene can dramatically improve its efficiency of expression.

Animals↗
PubMed1993

Manipulation of the repertoire of digestive enzymes secreted into the gastrointestinal tract of transgenic mice.

In non-ruminant livestock the energy which can be derived from dietary cellulose and xylan is limited by the inefficient microbial fermentation of these polymers in the hind-gut. Furthermore, in poultry, cereal-derived plant structural polysaccharides impair normal digestive function through the formation of gel-like structures, which trap nutrients rendering them unavailable to the animal. The nutrition of non-ruminant livestock could be significantly improved by the depolymerization of plant structural polysaccharides, through the introduction of cellulase activity into the small intestines of these animals. Here we describe the expression of Clostridium thermocellum endoglucanase E in the exocrine pancreas of transgenic mice. A non-glycosylated active enzyme is secreted into the small intestines, and is resistant to proteolytic inactivation, demonstrating the feasibility of generating non-ruminant animals with the endogenous capacity to depolymerize plant structural polysaccharides in the small intestines.

Animals↗