SEARCH · PubMed Health

Results for “Restrictive”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources

PubMed1993

Generation of cohesive ends on PCR products by UDG-mediated excision of dU, and application for cloning into restriction digest-linearized vectors.

We have investigated the use of dU excision by uracil N-glycosylase (UDG) to create cohesive ends on PCR fragments "mimicking" those generated by restriction enzymes. The feasibility of this approach for directional and nondirectional cloning using cohesive ends mimicking SacI or PstI ends is demonstrated by the subcloning of a 383 to 388-bp fragment of bovine basic fibroblast growth factor into restriction enzyme-linearized pT7T318U. UDG-mediated cohesive ends imperfectly matched to PstI-generated vector ends gave reasonable cloning efficiency and accuracy, suggesting that the approach may be extended to mimicry of other restriction enzymes producing 3' overhangs. The rapid and specific excision of dU by UDG (within 30 min at 37 degrees C) has several potential advantages over the use of restriction site-modified primers, including the avoidance of restriction cleavage at internal sites within the PCR product. Also, following ligation, the approach described may be used to prevent subsequent cleavage of the joined DNA segments by the restriction enzyme, that is, by not recreating the restriction enzyme recognition sequence at the junction, which may find application in gene engineering. By adapting the approach to use dU-containing linkers or "vectorettes," the approach may be used for cloning unknown sequences (e.g., by cDNA or genomic library construction) or for mimicking 5' overhang cohesive ends on PCR fragments.

Animals↗

PubMed1985

IgM induction in murine B hybridomas with Ia-restricted T cell clones: a monoclonal model for T and B cell interactions in antibody response.

The mechanism of MHC-restricted T and B cell interactions in antibody response was studied with IgM-inducible B hybridomas and antigen-specific helper T cell clones. B hybridomas were prepared by fusion between splenic B cells from (CBA/N (H-2k) X BALB/c (H-2d)) F1 (NBF1) male mice and a B lymphoma cell line, M12.4.5. A B hybridoma clone, 1M70, which expressed I-Ad but not I-Ak determinants was chosen in the present study. IgM secretion was induced in 1M70 when it was cocultured with a "resting" KLH-specific and H-2d restricted helper T cell clone in the presence of KLH. A "resting" KLH-specific and H-2k restricted T cell clone did not induce IgM secretion in 1M70 even in the presence of KLH. However, when these KLH-specific T cell clones were activated by KLH and appropriate antigen presenting cells, both H-2d and H-2k restricted T cell clones induced IgM secretion in 1M70 even in the absence of KLH. A monoclonal anti-I-Ad antibody inhibited IgM secretion induced by a "resting" H-2d restricted T cell clone, but not by an "activated" T cell clone. These results indicated that T cell clones recognized antigens in the context of Ia molecules on B hybridomas in a MHC-restricted manner and were activated to produce B cell stimulatory factors which in turn acted on B hybridomas in a non-MHC-restricted manner and induced differentiation of B hybridomas into IgM secreting cells.

Animals↗

PubMed1989

HLA class II restriction specificity of Dermatophagoides spp. reactive T lymphocyte clones that support IgE synthesis.

The results of recent experiments investigating the restriction specificity of cross-reactive, or Dermatophagoides farinae-specific, T cell clones isolated from an atopic individual with perennial rhinitis are reviewed. The restriction specificity was examined using serological inhibition, allogeneic presenting cells and murine fibroblasts expressing HLA-D region products. Although serological inhibition studies suggested that DR class II proteins were the major restriction elements used, the patterns of recognition observed with the allogeneic cell panel were complex, generally failing to correlate with the serologically defined MHC class II specificities. Analysis of the restriction patterns indicated that the majority of the T cell clones were restricted by DR beta III gene products and this was confirmed using murine fibroblasts expressing DRw52. DR beta I gene products functioned as restriction elements in the recognition of house dust mite allergen by the other clones. In an in-vitro model of allergen-dependent IgE synthesis, both DR beta I and DR beta III class II restricted T cells could be shown to provide functional help for IgE synthesized by autologous B cell-enriched populations.

Animals↗

PubMed1987

Cytotoxic T-cells elicited in cattle challenged with Theileria parva (Muguga): evidence for restriction by class I MHC determinants and parasite strain specificity.

The MHC restriction and parasite strain specificity of cytotoxic cells elicited in a group of Theileria parva (Muguga)-immunized cattle following homologous challenge, were investigated. The cytotoxic cells were specific for parasitized target cells and in 9 of the 10 animals examined, they were clearly genetically restricted. Cytotoxicity could be inhibited by monoclonal antibodies (MoAb) to class I MHC molecules but not by MoAb to class II molecules, indicating that a large component of the response was restricted by class I MHC determinants. Low levels of inhibition of cytotoxicity were also obtained with a MoAb to the T-cell subset marker BoT8, suggesting that at least part of the response was mediated by BoT8+ lymphocytes. When cytotoxic cells from individual cattle were assayed on panels of parasitized target cells, there was a close correlation between susceptibility of the target cells to lysis and sharing of BoLA-A locus-encoded specificities with the effectors. This observation, taken together with the knowledge that within several of the sets of BoLA-A-matched targets the relevant BoLA-A specificities were on different MHC haplotypes, indicated that the responses were restricted predominantly by BoLA-A products. In individual cattle there was a striking bias in the restriction of the response to one or other BoLA-A specificity. Among the six specificities represented, responses restricted by w6, w8 and KN18 consistently predominated over responses restricted by w7, w10 and w11. In the three cattle tested for parasite strain specificity, two showed complete specificity and one partial specificity for cells infected with the parasite stock used for immunization, T. parva (Muguga).

Animals↗

PubMed1981

Adoptive transfer of delayed-type hypersensitivity to Sendai virus. IV. Influence of thymic and lymphohaematopoietic cell type on H-2 restriction specificity of T effector cells.

The intrathymic versus extrathymic influences on H-2-restriction specificity of K,D- and I-region-restricted Sendai virus-immune T lymphocytes, which mediate a delayed-type hypersensitivity response in vivo, were investigated. K,D- and I-region-restricted Td lymphocytes of P1 leads to F1 fetal liver chimeras showed preference but no absolute restriction for the P1 haplotype. T effector lymphocytes of thymic chimeras expressed a slightly higher degree of restriction for the haplotype of the thymus graft than F1 leads to P1 chimeras, which might reflect the activity of T lymphocytes of thymic origin. The lack of absolute restriction of both K,D- and I-region-restricted Td lymphocytes to the haplotype the thymus suggests an additional pathway of T-cell maturation.

Animals↗

PubMed1981

HLA restriction of dinitrophenyl-specific cell-mediated cytotoxicity in vitro.

Lymphocytes from dinitrochlorobenzene-sensitized individuals can be stimulated in vitro by autologous dinitrophenyl (DNP)-conjugated lymphocytes to produce cytotoxic T lymphocytes (CTLs). The activity of these CTLs is specific for DNP-conjugated target cells, and there is no cross-reaction with nitrosodimethylaniline- or trinitrophenyl-conjugated target cell. Evidence is presented which makes it improbable that the cytotoxicity is caused by an antibody-dependent (ADCC-like) mechanism. Most of the DNP-specific cytotoxicity is restricted by the HLA-ABC antigens of th CTL donor, and there is only a low degree of lysis of DNP-conjugated allogeneic target cells not sharing HLA-ABC antigens with the donor. The CTLs did not lyle non-conjugated allogeneic target cells. When CTLs were tested against allogeneic DNP-conjugated targets sharing only one of the HLA-ABC antigens of the CLT donor, it was seen that the phenomenon of preferential restriction was pronounced; that is, only some of the antigens of the donor were restricting. A certain pattern has emerged: some antigens (e.g. A2) are good restricting antigens, some (e.g. B12) do not restrict, and some (e.g. B5) function well in one donor but not in another. The serologically cross-reacting antigens A2 and A28 did not restrict mutually. HLA-C antigens may in some donors function as restricting antigens.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1985

T lymphocyte responses to Coxsackie B4 and mumps virus. II. Immunoregulation by HLA-DR3 and -DR4 associated restriction elements.

A major part of the T lymphocyte response to mumps and Coxsackie B4 virus appears to be restricted by HLA-DR associated restriction elements. This was further corroborated in inhibition experiments using monoclonal antibodies reactive with different HLA class II molecules. Only antibodies reactive with DR molecules significantly inhibited the response. The frequencies of DR restricted antigen-reactive T lymphocytes (ARTL) to mumps and Coxsackie B4 virus were then investigated, using a limiting dilution assay. A decreased frequency of DR3 restricted ARTL to mumps and Coxsackie B4 was found compared to ARTL restricted by other DR associated elements. In contrast, an increased frequency of DR4 restricted ARTL to mumps and Coxsackie B4 was found. The results were similar for healthy individuals and Type 1 diabetic patients. No correlation was found between DR restriction elements and the frequencies of ARTL to varicella-zoster or PPD. The studies indicate that HLA-DR3 and DR4, which are associated with Type 1 diabetes, have a different regulatory function on the proliferative T lymphocyte response to mumps and Coxsackie B4.

Antibodies, Monoclonal↗

PubMed2006

Energy balance adiposity and breast cancer - energy restriction strategies for breast cancer prevention.

Excess adiposity over the pre- and postmenopausal years is linked to risk of postmenopausal breast cancer. Weight loss could potentially reduce risk amongst those with excess weight via beneficial effects on the hormonal (decreased circulating levels of oestradiol, testosterone, insulin) and secretory profiles of adipocytes (decreased production of leptin, tumour necrosis factor-alpha, interleukin 6 and increased production of adiponectin). Only modest reductions in adipose tissue are achieved and sustained with current weight loss programmes, which makes strategies to mitigate the adverse metabolic effect of adiposity a priority for cancer prevention. The adverse hormonal and secretory effects of adipose tissue are influenced substantially by acute changes in energy balance prior to changes in adiposity. Human and animal studies have shown dietary energy restriction to bring about favourable changes in circulating levels of insulin, leptin, sex hormone binding globulin, insulin-like growth factor-1, oestradiol, testosterone, reactive oxygen species, and the production and secretion of locally acting adipokines and inflammatory cytokines, that is, increased adiponectin and decreased interleukin-6. Achieving and sustaining energy restriction remains a difficult challenge. Intermittent energy restriction is a potential strategy for promoting periods of energy restriction on a long-term basis. Animal and human data suggest that intermittent energy restriction may have cancer preventative effects beyond that of chronic energy restriction and weight loss. Intermittent energy restriction may be a potential strategy for the primary prevention of breast cancer.

Adiponectin↗

PubMed2000

Beating the grog: an evaluation of the Tennant Creek liquor licensing restrictions.

OBJECTIVE: To review the effectiveness of, and community attitudes towards, increased restrictions on the availability of alcohol in Tennant Creek. METHOD: Estimates of quarterly per capita consumption of pure alcohol by persons aged > or = 15 years, admissions data from the local hospital, women's refuge and sobering up shelter, and police data on detentions in custody and common offences were compared for the 12 months prior and 24 months subsequent to the introduction of the restrictions. A random sample survey of residents aged > or = 18 years was conducted to ascertain attitudes towards the restrictions. RESULTS: Over the two years following the introduction of the restrictions, there was a reduction of 19.4% in annual per capita consumption of pure alcohol. This was accompanied by declines in: hospital admissions for acute alcohol-related diagnostic related groups; and persons taken into police custody and the proportions of offences reported on Thursdays. A majority of survey respondents was in favour of retaining or strengthening the existing restrictions. CONCLUSIONS: The restrictions were effective in reducing alcohol consumption and acute related harm and had the support of the majority of people in Tennant Creek. On the basis of this evidence, the NT Liquor Commission made a decision to retain them. Restrictions do not provide a simple answer to the problems associated with excessive alcohol consumption. However, they can be an effective part of a broad public health strategy to deal with such problems.

Adolescent↗

PubMed2005

Use of umbilical-cerebral Doppler ratios in predicting fetal growth restriction in near-term fetuses.

OBJECTIVE: To compare the sensitivity and specificity of different umbilical-cerebral ratios in the prediction and detection of fetal growth restriction in near-term fetuses when the umbilical arterial waveform is within normal. METHODS: A prospective cross-sectional observational study was carried out recruiting consecutive singleton pregnancies with clinically suspected fetal growth restriction after 34 weeks gestation. The umbilical-cerebral ratios were then calculated from the S/D, RI and PI values and correlated with immediate perinatal outcome. RESULTS: A total of 187 patients were recruited. Twelve cases had abnormal UA Doppler flow velocity waveform studies. Of the 175 with normal UA Doppler findings, 92 (53.1%) were confirmed to have fetal growth restriction (FGR) with birth weights below the tenth centile for gestation. The detection rate of FGR by ultrasound biometry was 96.7%. The mean umbilical artery S/D, RI and PI values were higher in the fetal growth restriction group, while the middle cerebral artery values were lower as compared to fetuses with no growth restriction. A small but significant difference was seen in the umbilical-cerebral ratios of the different indices between the two groups. Receiver operator characteristic curves showed that there was little difference between the performances of the S/D, RI or PI ratios and all had limited power in predicting fetal growth restriction. CONCLUSION: In the presence of normal umbilical artery Doppler waveforms, umbilical-cerebral ratios have limited power to predict fetal growth restriction.

Blood Flow Velocity↗

PubMed1993

Dietary restriction and aging.

The diet-restricted rodent model has been and is a major tool in experimental biogerontology. A spectrum of findings indicates that dietary restriction retards the aging processes of mice and rats, the most salient of which is the increase in mortality rate doubling time. It also maintains many physiological processes in a youthful state and, most strikingly, retards or prevents almost all age-associated disease processes. Current emphasis is on the mechanisms underlying the anti-aging actions of dietary restriction. The major effort for determining mechanism has focused on putative primary aging processes. A clue has emerged from the findings that it is the restriction of energy intake that is the dietary factor responsible for the anti-aging actions. However, reducing the metabolic rate is not involved. The challenge is to learn how the reduction of energy intake per animal (not per unit of body mass) is coupled to the retardation of aging processes. One of our working hypotheses is that dietary restriction alters nervous and/or endocrine functions that influence the characteristics (not the rate) of fuel use; this modulation in fuel-use characteristics is proposed to retard the aging processes. Our findings on carbohydrate metabolism are in accord with this view. Diet-restricted rats can use carbohydrate fuel as effectively as ad libitum fed rats while maintaining lower plasma glucose and insulin level. Maintenance of these low levels may protect against long-term damaging actions of these substances. Dietary restriction also protects against oxidative damage and, of course, oxidative damage is probably an inevitable component of fuel use.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMedDate not supplied

Impact of maternal activity restriction for preterm labor on the expectant father.

OBJECTIVE: To describe the impact on expectant fathers of their partners' activity-restricted pregnancies. DESIGN: Qualitative. SETTING: Private physician practices and two teaching hospitals in a large southern city. PARTICIPANTS: Self-selected sample of 15 fathers recruited within 2 weeks of initiation of their partners' activity restriction for high-risk pregnancy (phase 1) and 15 fathers recruited 1-2 years after a previous experience with their partners' activity-restricted pregnancies (phase 2). DATA COLLECTION: In phase 1, two semistructured interviews during the period of activity restriction and one interview after the birth. In phase 2, one semistructured, focus group interview. RESULTS: Fathers reported high levels of worrying immediately after diagnosis of their partners' preterm labor and initiation of activity restriction. Later, fathers also reported distress related to responsibility for child care, household management, and maintaining a supportive environment for their partners. Fathers reported few sources of personal support and little or no contact with health professionals during their partners' activity restriction. CONCLUSIONS: Activity restriction during pregnancy may have a significant psychological impact on expectant fathers. High levels of emotional distress may result in family disruption. Systematic nursing assessment and intervention may prevent or ameliorate distress.

Adaptation, Psychological↗

PubMed1995

Response to selection with restrictions while considering effective family number.

Response to restricted selection (genetic gain) from unrelated families was studied as a function of effective family number. The restrictions applied were maximum limits on the number of families among which selections are allocated, or on the number of individuals selected from a family. Numerical results were calculated for large normally-distributed populations. Effects of different selection methods, selection intensities, restriction intensities, and heritability are demonstrated. Selection with restrictions is a handy alternative for tradeoff between gain and effective number. Restricted phenotypic selection seemed favourable when both gain and effective number are desirable. Optimal-index selection without restriction or with low intensity of restriction on the contributions of families was proposed to produce maximum gain if low effective number is tolerable. The conclusions were verified for a real material.

Animals↗

PubMed1969

The use of dietary-restricted rat intestine for active transport studies.

1. The effect of dietary restriction (sufficient to produce a loss of about 32% of initial body weight) on intestinal active transport has been studied in the rat by the use of sacs of everted mid-small intestine. Eight D-sugars, four L-sugars and two D-amino acids were employed.2. Dietary restriction enhanced the normally occurring active transport of D-galactose, 3-O-methyl-D-glucose and D-methionine. In addition, sacs of dietary-restricted small intestine were able to concentrate in the serosal fluid D-fucose, D-xylose and D-histidine, which sacs of normal rat intestine could not do. The final (1 hr) serosal/mucosal concentration ratios produced for these actively transported substances were independent of net water movement.3. Sugars which were not concentrated in the serosal fluid of sacs of fully fed or dietary-restricted intestine were D-arabinose, D-fructose, D-glucosamine, D-mannose, L-arabinose, L-fucose, L-sorbose and L-xylose.4. The characteristics of D-fucose and D-xylose active transport suggest that they are transported by the mechanism which actively transports D-glucose. The comparatively low content of D-glucose in dietary-restricted intestine, compared with fully fed intestine, may be part of the explanation for observable active transport of D-fucose and D-xylose by dietary-restricted sacs.5. Thinning of the intestinal wall is believed not to be the cause of the enhanced active transport found during dietary restriction.6. The results show that dietary-restricted rat small intestine may, at times, be more useful than fully fed rat small intestine in the study of intestinal active transport.

Animals↗

PubMed2004

Modulation of body fluids and angiotensin II receptors in a rat model of intra-uterine growth restriction.

We previously reported that sodium restriction during pregnancy reduces plasma volume expansion and promotes intra-uterine growth restriction (IUGR) in rats while it activates the renin-angiotensin-aldosterone system (RAAS). In the present study, we proceeded to determine whether expression of the two angiotensin II (ANGII) receptor subtypes (AT(1) and AT(2)) change in relation to maternal water-electrolyte homeostasis and fetal growth. To this end, pregnant (gestation day 15) and non-pregnant Sprague-Dawley rats were randomly assigned to two groups fed either normal, or Na(+)-restricted diets for 7 days. At the end of the treatment period, plasma aldosterone and renin activity as well as plasma and urine electrolytes were measured. Determinations for AT(1) and AT(2) mRNA and protein were made by RNase protection assay and photoaffinity labelling, respectively, using a number of tissues implicated in volume regulation and fetal growth. In non-pregnant rats, Na(+) restriction decreases Na(+) excretion without altering plasma volume, plasma Na(+) concentration or the expression of AT(1) and AT(2) mRNA or protein in the tissues examined. In normally fed pregnant rats when compared to non-pregnant controls, AT(1) mRNA increases in the hypothalamus as well as pituitary and declines in uterine arteries, while AT(1) protein decreases in the kidney and AT(2) mRNA declines in the adrenal cortex. In pregnant rats, Na(+) restriction induces a decrease in plasma Na(+), an increase in plasma urea, as well as a decline in renal urea and creatinine clearance rates. Protein levels for both AT(1) and AT(2) in the pituitary and AT(2) mRNA in the adrenal cortex are lower in the Na(+)-restricted pregnant group when compared to normally fed pregnant animals. Na(+) restriction also induces a decrease in AT(1) protein in the placenta. In conclusion, these results suggest that pregnancy may increase sensitivity to Na(+) depletion by the tissue-specific modulation of ANGII receptors. Finally, these receptors may be implicated in the IUGR response to low Na(+).

Adaptation, Physiological↗

PubMed1980

Restriction and modification in group N streptococci: effect of heat on development of modified lytic bacteriophage.

The appearance of lytic bacteriophage against newly introduced starter strains used during commercial cheese manufacture occurs rapidly, and their origin is not well understood. In this study, members of the group N streptococci were examined for the presence of bacteriophage restriction and modification systems. Two streptococcal phages from Streptococcus cremoris TR and Streptococcus lactis C2 (phage designations tr and c2) showed restricted lytic development on S. cremoris 799 and KH, respectively. Efficiency of plaquing was 1.9 x 10 for tr plaqued on 799 and 2.1 x 10 for c2 plaqued on KH. After passage through the restrictive hosts, these phages demonstrated high lytic ability for formerly restrictive hosts. Stress of the restrictive host strains at temperatures of 40 to 50 degrees C resulted in a significant increase in the efficiency of plaquing of restricted bacteriophages. Elevated temperatures are encountered during commercial cheese manufacture. The results suggested that the temporary loss of host restriction activity with the resulting modification of nonspecific bacteriophage may contribute directly to the appearance of lytic phage against new starter strains.

Journal Article↗

PubMed1994

Non-major histocompatibility complex-restricted cytotoxic activity of blood mononuclear cells stimulated with secreted mycobacterial proteins and other mycobacterial antigens.

Several observations indicate that non-major histocompatibility complex (MHC)-restricted cytotoxicity, mediated for example by natural killer cells and lymphokine-activated killer cells, may serve as an important antimicrobial defense mechanism. The purpose of the present study was to investigate the influences of different mycobacterial antigens on non-MHC-restricted cytotoxicity and further to investigate the ways by which various lymphocyte subpopulations contribute to the development of this cytotoxicity. Non-MHC-restricted cytotoxicity was induced following stimulation of mononuclear cells with tuberculin purified protein derivative, Mycobacterium bovis bacillus Calmette-Guérin (BCG), short- and long-term culture filtrates of virulent Mycobacterium tuberculosis H37Rv, and 30-31-kDa secreted mycobacterial protein. These antigens also induced proliferation and production of gamma interferon. The CD4+ cells proliferated and expressed interleukin-2 receptors following stimulation with mycobacterial antigens. Depletion studies after antigen stimulation showed that the cytotoxic effector cells were CD16+ CD56+ and CD4-; the CD4+ cells alone did not mediate non-MHC-restricted cytotoxicity. To evaluate the influence of CD4+ cells on the development of non-MHC-restricted cytotoxicity, blood mononuclear cells were depleted of CD4+ cells before antigen stimulation. When mononuclear cells were incubated with purified protein derivative or short-term culture filtrate in the absence of CD4+ cells, cytotoxic activity was reduced. This reduction was abolished by interleukin-2 but not by gamma interferon. We conclude that several mycobacterial antigens are able to induce non-MHC-restricted cytotoxicity. This study indicates that non-MHC-restricted cytotoxicity following stimulation with mycobacterial antigens is induced by cytokines released by antigen-specific activated CD4+ cells.

Antigens, Bacterial↗

PubMed2000

Cellular responses to postsegregational killing by restriction-modification genes.

Plasmids that carry one of several type II restriction modification gene complexes are known to show increased stability. The underlying mechanism was proposed to be the lethal attack by restriction enzyme at chromosomal recognition sites in cells that had lost the restriction modification gene complex. In order to examine bacterial responses to this postsegregational cell killing, we analyzed the cellular processes following loss of the EcoRI restriction modification gene complex carried by a temperature-sensitive plasmid in an Escherichia coli strain that is wild type with respect to DNA repair. A shift to the nonpermissive temperature blocked plasmid replication, reduced the increase in viable cell counts and resulted in loss of cell viability. Many cells formed long filaments, some of which were multinucleated and others anucleated. In a mutant defective in RecBCD exonuclease/recombinase, these cell death symptoms were more severe and cleaved chromosomes accumulated. Growth inhibition was also more severe in recA, ruvAB, ruvC, recG, and recN mutants. The cells induced the SOS response in a RecBC-dependent manner. These observations strongly suggest that bacterial cells die as a result of chromosome cleavage after loss of a restriction modification gene complex and that the bacterial RecBCD/RecA machinery helps the cells to survive, at least to some extent, by repairing the cleaved chromosomes. These and previous results have led us to hypothesize that the RecBCD/Chi/RecA system serves to destroy restricted "nonself" DNA and repair restricted "self" DNA.

Chromosomes, Bacterial↗