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Biomedical subjects

R Meir

Publications and source records attributed to R Meir.

At least 19 recordsLinked to original sources
PubMed2005

Vaccine and adjuvant activity of recombinant subunit B of E. coli enterotoxin produced in yeast.

Escherichia coli heat-labile enterotoxin (LT) and cholera toxin (CT) have been studied intensively as vaccines against diseases caused by those bacteria and as adjuvants for mucosal vaccination. Two major problems interfere with the use of these promising adjuvants: their toxicity and the residual bacterial endotoxins mixed with the desired LT. In this study, subunit B of LT was expressed in Pichia pastoris yeast cells (yrLTB) and the recombinant protein was purified and concentrated by ion-exchange chromatography. The final yield of the recombinant protein was 5-8 mg/l induction medium. The molecule is in pentameric form and binds to GM1 gangliosides. When given orally to chickens, anti-LTB antibodies were produced, exhibiting its ability to cross the digestive system and induce an immune response. The adjuvant activity of yrLTB was proven by fusing it to viral protein 2 (VP2) of infectious bursal disease virus. Birds intramuscularly vaccinated with this molecule exhibit 70-100% protection, in a dose-response-dependent manner. This method eliminated the bacterial endotoxins and enabled the production of large quantities of LTB. Expression in a eukaryotic system allows the production of fusion proteins that require post-translational modifications. This may allow oral vaccination with a protein fused to yrLTB. The approach described in this study will enable the efficient production of a non-toxic, eukaryotically expressed enterotoxin as a vaccine against the toxin itself or as a carrier or adjuvant for foreign vaccine molecules.

Adjuvants, Immunologic↗
PubMed2005

S1 gene characteristics and efficacy of vaccination against infectious bronchitis virus field isolates from the United States and Israel (1996 to 2000).

The S1 genes of isolates of avian coronavirus infectious bronchitis virus (IBV) from commercial chickens in the US and Israel (20 isolates from each country) were studied using reverse transcription-polymerase chain reaction restriction fragment length polymorphism and sequencing. Partial sequences spanning the amino terminus region of S1 from amino acid residues 48 to 219, based on the Beaudette strain, were used for analysis. Phylogenetic clustering and high-sequence identity values were used to identify isolates that appeared to be derived from live IBV vaccines used in the two countries. Novel variant strains, unrelated by S1 sequencing and restriction fragment length polymorphism analyses to reference and vaccine strains, were also identified. Based on S1 sequence identity to available vaccines, the potential to use vaccination to control IBV infections was evaluated. Vaccination with commercial live strains Massachusetts (Mass), Arkansas (Ark) or DE/072/92, generally produced immunity against vaccine-related field isolates displaying high S1 sequence similarities (> or = 90%) to the respective vaccine strains. Immunization with a bivalent vaccine containing the Mass and Ark strains provided good cross-protection, averaging 81% against challenge with five variant isolates from the US having amino acid identity values ranging from 62 to 69% to Mass and from 68 to 83% to Ark, respectively. In contrast, the H120 vaccine strain induced low levels of protection, ranging from 25 to 58% against variant field isolates from Israel with amino acid identity values from 65 to 67%.

Animals↗
PubMed2004

Identification of a novel nephropathogenic infectious bronchitis virus in Israel.

A novel infectious bronchitis variant, designated as IS/885/00, associated with nephritis, was isolated from outbreaks in 23 broiler farms in Israel. The virus was first identified by reverse transcriptase-polymerase chain reaction and showed a distinct restriction fragment length polymorphism pattern from previously described Israeli isolates. Sequence analysis of the S1 gene and the deduced amino acid sequence revealed 97.2% protein similarity to genotype IS/ 720/99 and 71.6% similarity to the vaccine strain H120, the only strain permitted for use in this country. A database search in GenBank revealed a closely related isolate from Egypt, Egypt/Beni-Seug/01, with 96.6% similarity. Other published nephropathogenic infectious bronchitis virus strains/isolates shared less than 77% similarity with IS/885/00. A vaccine protection test in specific-pathogen-free chicks indicated 91% protection to the trachea and only 25% protection to the kidneys in vaccinated birds challenged with IS/885/00.

Amino Acid Sequence↗
PubMed2001

Best estimated inverse versus inverse of the best estimator.

The construction of a feed-forward controller frequently requires the estimation of an inverse function. Two possible methods to achieve this are: (i) learning the best estimated inverse (BEI), a method that is sometimes referred to as direct inverse learning and (ii) learning the inverse of the best estimator (IBE), a method that is sometimes referred to as indirect inverse learning. We analyze a general control problem, in the presence of noise, and show analytically that these two methods are asymptotically significantly different, even for simple linear non-redundant systems. We further demonstrate that the IBE method is typically superior for control purposes.

Artifacts↗
PubMed2001

Physical fitness qualities of professional rugby league football players: determination of positional differences.

A total of 146 professional rugby league football players, contracted to 2 teams competing in England (n = 45) and Australia (n = 101), participated in this study. All players completed the following series of physical fitness performance tests: 1 repetition maximum squat and bench press, 15- and 40-m sprint, agility run, 5-minute run for distance, 60-second sit-up, 30-second plyometric push-up, and measurement of body weight and subcutaneous skinfold (4 sites). Analysis of variance with a criterion alpha level of p < 0.05, was used to determine if any significant difference could be found when grouping players into 3 different positional categories typically identified in the sport. There were a number of significant differences with respect to test results between categories, and this was apparent for all 3 systems of categorization. On the basis of these findings, we recommend that to more efficiently structure the physical fitness training of players, the players should be grouped either according to the 2 broad positional categories of forwards or backs or according to the 4 categories of forwards, distributors, adjustables, and outside backs. Grouping players according to the 9 specific positions played on the team is not warranted.

Analysis of Variance↗
PubMed1998

Almost linear VC-dimension bounds for piecewise polynomial networks

We compute upper and lower bounds on the VC dimension and pseudo-dimension of feedforward neural networks composed of piecewise polynomial activation functions. We show that if the number of layers is fixed, then the VC dimension and pseudo-dimension grow as WlogW, where W is the number of parameters in the network. This result stands in opposition to the case where the number of layers is unbounded, in which case the VC dimension and pseudo-dimension grow as W2. We combine our results with recently established approximation error rates and determine error bounds for the problem of regression estimation by piecewise polynomial networks with unbounded weights.

Journal Article↗
PubMed1997

Anserine bursitis and non-insulin dependent diabetes mellitus.

OBJECTIVE: To determine the relationship between non-insulin dependent diabetes mellitus (NIDDM), knee pain, and anserine bursitis, and its relation to sex, age, or body mass index (BMI). METHODS: Ninety-four consecutive patients with NIDDM, 66 women and 28 men, and 57 nondiabetic patients, 36 women and 22 men, were examined at an outpatient clinic of a tertiary care hospital. Date of onset in patients with NIDDM was noted, and serum was analyzed for either hemoglobin A1C (HbA1C) or glycosylated hemoglobin (GHb) in 69 of these patients. Anserine bursitis was diagnosed if knee pain and tenderness at the bursal site were found on examination. RESULTS: On examination 34 (36%) patients with NIDDM were found to have anserine bursitis. Of these, 31 (91%) were women and 3 (9%) were men (p < 0.05). Age, BMI, duration of diabetes, HbA1C or GHb, and age of onset of diabetes were found not to differ significantly between patients with and those without anserine bursitis. CONCLUSION: A relationship exists between NIDDM, knee pain, and anserine bursitis unrelated to age, BMI, duration and control of diabetes, and age at the diagnosis of diabetes.

Adult↗
PubMed1992

[Age- and sex-specific standard values of colonic transit time in healthy subjects].

Use of radiopaque markers with a plain X-ray of the abdomen is a simple technique to measure mean segmental and total colonic transit time. We evaluated 128 healthy volunteers with a mean age of 40 years (range 20-81 years) from three different parts of Switzerland to assess age and sex specific normal transit times. In men and women colonic transit time was not influenced by age. The mean transit time was significantly shorter in men than in women (30 +/- 2 hours versus 41 +/- 3 hours: p less than 0.05). In men the transit time was also influenced by smoking. Non-smoking men had a significantly shorter transit time than smokers (26 +/- 2 hours versus 40 +/- 5 hours: p less than 0.05). In women, neither smoking nor the menstrual cycle influenced transit time. For normal colonic transit time we recommend up to 66 hours for smoking men, up to 44 hours for non-smoking men and up to 70 hours in general for women.

Adult↗
PubMed1991

Human growth hormone and insulin-like growth factor-1 enhance the proliferation of human leukemic blasts.

As the number of long-term survivors of childhood leukemia increases, growth retardation has emerged as a significant complication. Treatment of these children with growth hormone (GH) has been suggested and sporadically implemented. We, therefore, studied the effect of human GH (hGH) and its by-product insulin-like growth factor-1 (IGF-1) on the growth of leukemic cells in vitro. Under serum-free conditions hGH and IGF-1 induced a significant dose-dependent proliferative effect on promyelocytic leukemia (HL60) and Burkitt's lymphoma (Daudi) cell lines. Anti-hGH antibodies negated the stimulatory effect of hGH and anti-IGF-1 serum abrogated the growth-promoting effect enhanced by IGF-1. Similar statistically significant stimulatory properties were found when freshly obtained marrow cells from four of five acute lymphoblastic leukemia (ALL) of childhood and four acute myelogenous leukemia (AML) patients were studied in ALL and AML blast-cell clonogenic assays. ALL colonies increased numerically by 72% (P less than .025) and AML colonies by 92% (P less than .01) in the presence of hGH at concentrations of 2.5 x 10(2) and 3.0 x 10(2) ng/mL, respectively. IGF-1 stimulated ALL and AML blast-colony growth at concentrations ranging from 0.05 to 0.5 ng/mL by up to 105% (P less than .025) and 65% (P less than .03), respectively. Our in vitro data suggest that circulating hGH and IGF-1 may promote leukemic blast cell replication in vivo, and the supplemental administration of hGH to leukemia patients in remission must be carefully monitored for early relapse.

Bone Marrow↗