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Results for “Modifiable factors”

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At least 163 records · Page 9Linked to original sources

PubMed2001

Evidence for the presence of a novel Kv4-mediated A-type K(+) channel-modifying factor.

1. Subthreshold-operating transient (A-type) K(+) currents (I(SA)s) are important in regulating neuronal firing frequency and in the modulation of incoming signals in dendrites. It is now known that Kv4 proteins are the principal, or pore-forming, subunits of the channels mediating I(SA)s(.) In addition, accessory subunits of Kv4 channels have also been identified. These either have no effect or slow down the inactivation kinetics of Kv4 channels. However, in many neuronal populations the I(SA) is faster, not slower, than the current generated by channels containing only Kv4 proteins. 2. Evidence is presented for the presence in rat cerebellar mRNA of transcripts encoding a molecular factor, termed KAF, that accelerates the kinetics of Kv4 channels. Size-fractionation of cerebellar mRNA in sucrose gradients separated the high molecular weight mRNAs (4-7 kb) encoding KAF from the low molecular weight ones (1.5-3 kb) encoding factors that slow down the inactivation kinetics of Kv4 channels. The latter were identified as KChIPs using anti-KChIP antisense oligonucleotides. 3. Both anti-KChIP and anti-Kv4 antisense oligonucleotides failed to eliminate KAF's activity from the high molecular weight mRNA fraction, thus suggesting that KAF might be a novel subunit(s) that can contribute to generating native I(SA) channel diversity. 4. The time course of the currents expressed by KAF-modified Kv4 channels resembles more closely the time course of the native I(SA) in cerebellar granule cells.

Animals↗

PubMed1989

[Factors modifying remission in cytostatic chemotherapy of squamous cell carcinoma recurrence in the area of the head and neck].

From 1981 to 1986 eighty-five patients underwent palliative chemotherapeutic treatment at the E.N.T. Department of the University Hospital in Graz. In seventy-three recurrent tumours comparable RR were achieved with ADM/CDDP as well as with MTX/5-FU. In 39 patients a second treatment after failure or relapse of previous therapy was applied, containing predominantly CDDP/BLM resulting in a RR of 18%. The tumour stage proved to be the single most important factor concerning response to treatment in first as well as second line chemotherapy. Stage IV tumours showed a significantly lower RR compared to neoplasms without large neck masses (stages II, III), the RR being 59% versus 19% (p = 0.01). Furthermore, performance status, preceding therapeutical modalities, and location of the tumours were shown to be of secondary prognostic importance. In the latter group, age and the time interval between recurrences appeared to be of no significance. To evaluate the most effective regimen, highly differentiated analysis of all available data is imperative.

Aged↗

PubMed1996

Factors modifying growth hormone estimates in immunoassays.

Growth hormone (GH) in human serum has been measured for more than 30 years and during this period it has been used diagnostically in growth disturbances and GH disorders. The first GH determinations were by radioimmunoassays using polyclonal antibodies. Due to the low specificity of these assays and the variable molecular appearance of GH, higher levels were obtained than with later assays employing two highly specific monoclonal antibodies. Because of this variability between assays, empiric GH cutoff levels had to be developed in different laboratories. However, with the growing need for more sophisticated diagnosis, especially in adulthood GH deficiency, knowledge of factors influencing the individual GH assays is required. Since GH deficiency in adulthood is now treated with GH substitution therapy, the relevance of factors influencing GH estimates has become increasingly evident, because no specific symptoms exist in adult GH deficiency.

Adult↗

PubMed2004

[Gene-gene and gene-environment interactions as modifier factors of prostatic cancer risk: "a case-only" design study].

BACKGROUND: The role of susceptibility low penetrance genes and environmental factors in the etiology of prostate cancer (PCa) is unclear, but may involve in some cases multiple alleles at multiple loci. AIM: To evaluate the association of gene-gene and gene-environment interactions with PCa. PATIENTS AND METHODS: One hundred three subjects with biopsy proven PCa were studied, using a case-only design. All were interrogated about smoking habits. Polymorphisms for Glutathione-S-transferase (GS7) and Cytochrome P4501A1 (CYP1A1), were measured in DNA extracted from peripheral lymphocytes, using a restriction fragment length polymorphism analysis. RESULTS: Our findings suggest that gene-gene interactions between GSTT1 and CYP1A1 high risk genotypes were positive modifiers and had a high predictive value for the presence of PCa, compared with non-susceptibility genotypes. The interaction between susceptibility genotypes and smoking did not modify the risk for PCa. CONCLUSIONS: Gene-gene interactions may play a role modulating the susceptibility to PCa in a proportion of affected individuals.

Aged↗

PubMed1977

The role of nicotinamide and of certain other modifying factors in diethylnitrosamine carcinogenesis: fusaria mycotoxins and "spontaneous" tumors in animals and man.

Pretreatment of rats with large doses of nicotinamide, which has been shown to increase the incidence of pancreatic islet-cell tumors after streptozotocin and after heliotrine, appears to promote the development of kidney neoplasias in rats given several doses of diethylnitrosamine. Nicotinamide, one of the B vitamins, and a constituent of NAD coenzymes, will prevent the depletion of NAD coenzymes by alkylating agents. It may protect the animal to some extent from the acute effects of hepatocarcinogens but not from the induction of tumors, although it may change the localization of the latter. The possible mechanisms involved in the action of nicotinamide and of certain other modifying agents are discussed. Attention is drawn to the possibility that pituitary, mammary and certain other tumors that sometimes occur among the controls, as well as among experimental animals, may be due to the occasional presence in laboratory animal diets of estrogenic and/or toxic secondary metabolites of the field fungi, Fusaria. Mycotoxins, such as zearalenone and the trichothecenes, are also likely to contaminate human foods; this could explain why multiple tumors in man occur mainly in the sex organs and in the digestive tract.

Animals↗

PubMed1999

Epidermal growth factor modifies the expression and function of extracellular matrix adhesion receptors expressed by peritoneal mesothelial cells from patients on CAPD.

BACKGROUND: Efficient peritoneal dialysis depends on an intact layer of mesothelial cells that line the peritoneal membrane. This layer is disrupted in patents on continuous ambulatory peritoneal dialysis during episodes of peritonitis (acute injury) and replaced by fibrous tissue during extended dialysis (chronic injury). Little is understood of human peritoneal mesothelial cell (HPMC) responses to wounding and episodes of peritonitis. METHODS: HPMC were harvested from spent peritoneal dialysis effluent and maintained under defined in vitro conditions. Adhesive interactions with extracellular matrix (ECM) molecules and chemotactic and wound-healing responses were measured in vitro using purified ECM molecules. RESULTS: HPMC express multiple functional cell receptors recognizing and binding to ECM molecules, including several members of the integrin family. HPMC exhibit directed migration in wound healing and chemotaxis assays with ECM molecules. Epidermal growth factor (EGF) stimulates a reversible change to a fibroblastic phenotype, accompanied by increased expression of beta1 integrins, particularly alpha2beta1, increased adhesion to type I collagen, and significantly greater HPMC migration on type I collagen in wound healing and chemotaxis assays. CONCLUSIONS: HPMC possess the migratory capacity to contribute to the efficient repair of damaged peritoneal membrane after acute injury, and growth factors, such as EGF, facilitate peritoneal membrane healing by augmenting cell adhesion and migration.

Cell Movement↗

PubMedDate not supplied

[Factors modifying late bronchial response in the bronchial provocation test in asthmatic children].

When the test of bronchial provocation with inhalant allergens is performed in atopic asthmatics, we may find an immediate response (IR), a late response (LR) or a dual response (IR-LR). The immediate response occurs between 10 to 30 minutes after the allergenic exposition and it is resolved spontaneously in about one to two hours. A proportion of these patients, estimated around 47-73% presented a LR. The LR is manifested 3 or 5 hours after the inhalation test, maximum at 6-12 hours and may persist until 24 hours. The late response serves as a clinical model of asthma because the bronchial response is more prolonged and severe than the immediate response. This is best controlled with corticosteroids while bronchial reversibility is difficult with sympathomimetics only, a fact commonly observed in the natural course of asthma. The early response was observed to be in relation with multiple factors more predictable than the late response. The object of this work was to evaluate if the LR was related with factors such as the degree of obstruction previous to the test, the intensity of immediate bronchial response and the maximum dose of inhaled allergen. The present study was performed in 34 children of both sexes with ages ranging between 6 and 14 years, diagnosed with bronchial asthma caused by Dermatophagoides (26 patients), and Alternaria (8 patients) through the score of Foucard with positive bronchial provocation test with the allergen. The BPT was performed according to the method described for Cockcroft, utilizing a continuous pressured nebulizer, inhaling for two minutes at current volume. We employed the De Villbis 646 model nebulizer with flow of air at 6 l/min and output at 0.13-0.16 ml/min. The inhaled concentrations of allergen progressively increased by ten fold, in Dermatophagoides 0.01; 0.1; 1 and 10 BU/ml, and for Alternaria 1/1,000,000, 1/100,000 and 1/10,000 P/V. Ten minutes after each dose a spirometric function with pneumoscreen Jaeger was performed. If the FEV1 was decreased by 20% from the control value, we considered the IR positive. The late response was evaluated through an hourly control of the peak respiratory flow rate (PEFR) with a Mini Wright within a 24 hours period after the test, respecting nocturnal sleep. We considered positive (LR) if PEFR fall was equal or superior to 40% of the basal value and the presence of bronchial symptoms.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1981

Factors modifying vitreous pressure in cataract surgery.

A prospective study of 267 intracapsular cataract extractions was conducted to assesses what makes an eye soft and capable of safely receiving an intraocular lens implant. The study showed that the use of glycerol, given orally before the operation, plus retrobulbar anesthesia is the most effective way of reducing the vitreous pressure, that there is a direct relation between this reduction and age, and that there is no apparent correlation between the preoperative intraocular pressure and the vitreous pressure.

Adult↗

PubMed1989

Factors modifying valproate plasma level/dose ratio: age, sex, dose and plasma level.

Valproate plasma level/dose (L/D) ratios obtained from 155 outpatients under long-term monotherapeutic regimen have been studied. Analytical data were obtained by enzymatic immunoassay (EMIT) from paired samples taken before the morning drug dosage. L/D ratios were increased with age and plasma level and decreased with dose. There were no sex differences in L/D in the different age, dose and concentration groups. L/D ratios were higher than those found by other researchers in our country.

Adolescent↗

PubMed1990

Factors modifying the use of anaesthetic drugs in the elderly.

The elderly are forming an ever greater proportion of our hospital population. The process of ageing produces a gradual erosion of all the body's margins of safety coupled with a decreasing ability to adapt. This has significant effects on the physiological responses to the surgical and pharmacological trespass encountered during anaesthesia. In addition elderly people often suffer from multiple pathology and polypharmacy, both of which play important roles in the selection of the optimal anaesthetic regimen.

Aged↗

PubMedDate not supplied

[Bone marrow transplantation as a factor modifying the recovery processes of hematopoietic tissue in irradiated mice].

In experiments on (CBA X C57Bl)F1 mice exposed to 60Co-gamma-radiation in a dose of 8.5 Gy a different degree of blood system recovery was demonstrated after bone marrow transplantation in the following quantities; 2 X 10(5), 2 X 10(6) or 5 X 10(6) cells. With the smallest number of myelocaryocytes transplanted the regeneration of haemopoiesis, especially granulopoiesis, was relatively more pronounced (disproportionally to the number of the transplanted cells).

Animals↗

PubMedDate not supplied

[Bone marrow autotransplantation as a factor modifying the process of hematopoietic tissue recovery in irradiated guinea pigs].

Guinea pigs were subjected to myeloexfusion 30-90 min before gamma-irradiation with a superlethal dose of 8 Gy. Immediately after irradiation, the bone marrow (4 X 10(7) cells) was autotransplanted. The automyelotransplantation provided a pronounced stimulation of haemopoiesis and substantially shortened the time of its regeneration. The myeloexfusion in some of the exposed control animals had a beneficial effect in their resistance and blood system recovery.

Animals↗

PubMed2002

Dose-effect modifying factors in radiation protection--a 1967 National Commission on Radiation Protection document revisited.

In 1967 Subcommittee M-4 of the National Commission on Radiation Protection proposed a system for evaluating, summing and reporting occupational exposures. It appears that some 30 years later these concepts could be implemented in a system of radiation protection based on Katz's cellular track structure model, which is able to quantify and predict the response of systems relevant to radiation protection, such as survival or oncogenic transformations in cell cultures, enzymes, bacteria or whole organisms. As a consequence of this approach, an m-power-law (with m ranging between 2 and 3.5) dependence of effect, or radiation risk, after doses of standard Co-60 radiation, would follow.

Effect Modifier, Epidemiologic↗

PubMed1983

Factors modifying the local arterial hyperresponsiveness of vibration-induced white finger.

The extent and duration of the vibration-induced hyperresponsiveness of arterial smooth muscle to noradrenaline increased as the period of vibratory stimulation became longer. Division of a fixed stimulation time into a few shorter units interposed by intermissions decreased the extent and duration of the hyperresponsiveness. The shorter the length of each unit, the less the hyperresponsiveness. Verapamil effectively suppressed the appearance of the hyperresponsiveness, whereas pretreatment with phentolamine only partially inhibited its appearance. Administration of vitamin E was effective in suppressing the vibration-induced rise of responsiveness to noradrenaline in plasma.

Animals↗

PubMed1994

Extraversion as a modifying factor in catecholamine and behavioral responses to ethanol.

Individual differences in catecholamine response to stress and ethanol were tested in extraverts and introverts on the basis of Eysenck's drug postulate claiming that introverts would be less susceptible to sedative drugs like ethanol. Forty-four healthy males received either 0.8 g/kg ethanol mixed into a drink of caffeine-free cola or a respective placebo and were tested with a stressful mental arithmetic task before and 40 min after the intake of the drink. Plasma catecholamines were determined from blood samples drawn at five defined intervals from an indwelling cannula and self-ratings on deactivation, relaxation, and anxiety were obtained as well as quality and quantity of performance in the arithmetic task. Results showed that there was no difference in catecholamine stress responses between introverts (Ex -) and extraverts (Ex +) before the drink, but that the intake of the fluid (both ethanol and placebo) resulted in higher norepinephrine (NE) increases in Ex - than in Ex +. The combined effects of ethanol and stress yielded larger responses of longer durations in Ex - than in Ex +. The concomitant psychological changes showed larger reductions in anxiety and increases in relaxation as well as larger decrements in quality of performance (% errors) in introverts in spite of their higher catecholamine increases. Thus, the predictions on the basis of arousal theory could not be verified experimentally and the drug postulate has to be modified in the sense that introverts probably have a higher depletion of NE in the central nervous system under physical but not under mental stress which is reflected by higher levels in the plasma and respective decreases in performance and activation.

Adult↗

PubMedDate not supplied

Sociodemographic factors modifying the effect of environmental lead on neuropsychological development in early childhood.

A long-term prospective cohort study was conducted to examine the association between prenatal and postnatal exposure to environmental lead and childhood neuropsychological development. The possible interactive effects of blood lead and some covariates on early development were explored in this study. Our data suggest that gender of the child modifies the effect of lead on the neuropsychological development during early childhood. At the ages of 2 and 4 years, girls appear to be more sensitive than boys to the neuropsychological effects of lead. However, there is no significant modification of the effect of lead by some other covariates, such as parental smoking, socioeconomic status, home environment, birth weight, and the kind of infant feeding. Evidence of interactions between environmental lead exposure and other covariates in the causation of neuropsychological deficits in childhood underscores the desirability of considering both main effects and interactions in this area of research. Such effects, if confirmed, may have implications for public health intervention strategies.

Analysis of Variance↗

PubMed2002

[Damaging impacts at the critical time periods of prenatal ontogenesis as a factor modifying the cerebral structural development and postnatal behavior reactions].

Results of a study of the nature of changes in the rat neocortex, which were observed during an early postnatal period (postnatal days 1 to 10) and which were induced by a single prenatal hypoxia on the 16th or 19th embrionic day (E16, E19), are presented in the paper. Acute hypoxia, administered on E16, was shown to result in an underdevelopment of cortical layers as well in damage to cell orientation and differentiation, i.e. it disturbed the histogenic processes (proliferation, migration and differentiation), which are most active at this time period. An immunohistochemical examination of the brain made during the postnatal period after an intrauterine hypoxia suggests that damage to proliferation and differentiation occurred in glial cells. Hypoxia administered on E19, when the level of proliferation in the brain was lower, had a less pronounced damaging effect. Deviations in the neocortical structure and in the animal's behavior found during the postnatal period could be caused by the heterochromic and heteromorphous development of brain regions in the fetus.

Animals↗

PubMed1997

[Factors modifying postoperative astigmatism after no-stitch cataract surgery].

BACKGROUND: One of the main advantages of the no-stitch technique in cataract surgery is that induced astigmatism occurs less frequently than with any other procedure and stabilizes within a very short time postoperatively. The resultant high wound strength enabled us to alter the incision parameters in an attempt to identify those which influenced postoperative astigmatism, the ultimate goal being to improve the prognosis of the expected astigmatism. Since the influence of tunnel width and incision length and shape were well known, we investigated the influence of incision depth and site and that of various parameters in a prospective randomized and controlled clinical trial. METHODS: The study included 256 eyes with a 7-mm tunnel incision as examined in 256 patients. The following subgroups of 27 eyes each were investigated: primary incision depth of 300 microns versus 500 microns, limbal incision versus scleral incision, scleral incision in the 12 o'clock position versus temporal scleral incision, and limbal incision in the 12 o'clock position versus temporal limbal incision. In another group the influence of age, IOP, axial length of the globe, preoperative astigmatism, corneal diameter, and postoperative astigmatism as measured by the keratometer were all assessed using Spearman's correlation coefficient. RESULTS: Temporal incisions made 2 mm posterior to the limbus resulted in induced astigmatism of 0.64 +/- 0.22 D 6 months postoperatively, which was less than after incisions in the 12 o'clock position (0.98 +/- 0.40 D). Induced astigmatism was highest after limbal incisions in the 12 o'clock position (1.31 +/- 0.60 D), yet was less if a temporal limbal incision was made (0.84 +/- 0.52 D). Incision depth did not have significant influence on induced astigmatism. Of the parameters, age (Spearman's correlation coefficient after 4 weeks 0.34; P = 0.002; after 6 months 0.28; P = 0.01), and preoperative astigmatism (Spearman's correlation coefficient after 4 weeks 0.28; P = 0.01; after 6 months 0.27; P = 0.01) had a significant influence on postoperative astigmatism. CONCLUSIONS: These findings indicate that induced astigmatism was highest after limbal incisions in the 12 o'clock position and lowest after scleral incisions in the temporal position. Age and preoperative astigmatism were also found to influence induced astigmatism significantly. All of these factors have to taken into account to minimize postoperative astigmatism.

Adult↗