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Biomedical subjects

A C de Groot

Publications and source records attributed to A C de Groot.

At least 19 recordsLinked to original sources
PubMed2001

Relationship between cardiac metaiodobenzylguanidine uptake and hemodynamic, functional and neurohormonal parameters in patients with heart failure.

BACKGROUND: Sympathetic activation plays a pivotal role in heart failure attributing to the disease process and symptoms of the patient. Myocardial sympathetic activity can be visualized using radioiodinated metaiodobenzylguanidine 123I-MIBG, a structural analogue of norepinephrine (NE). AIM OF THE STUDY: We investigated whether a relation exists between myocardial MIBG uptake and different functional, hemodynamic and neurohormonal parameters in patients with chronic heart failure. METHODS AND RESULTS: The study comprised 52 patients with stable congestive heart failure functional class II or III and left ventricular ejection fractions of <35%. The heart/mediastinum ratio (H/M ratio) was calculated to quantify myocardial MIBG uptake. A significant correlation was found between peak oxygen consumption and maximal exercise duration as exercise parameters and H/M ratio of MIBG (R, respectively, 0.36 and 0.4, P<0.05). From all other measured parameters, only plasma NE showed a significant correlation with the H/M ratio of MIBG. CONCLUSION: Cardiac sympathetic activity, as measured by myocardial MIBG uptake, is correlated with peak exercise parameters.

3-Iodobenzylguanidine↗
PubMed2001

Ectropion caused by periocular dermatitis.

A 78-year-old woman had ectropion of both lower eyelids 4 weeks after the appearance of dermatitis around the eyes. Treatment with topical corticosteroids resulted in disappearance of both dermatitis and ectropion within 10 days. No relevant contact allergies were found. Her advanced age and a familial tendency toward edema around the eyes, indicating preexisting loss of elasticity, probably facilitated this apparently rare reaction.

Administration, Topical↗
PubMed1999

Prediction of metal bioavailability in Dutch field soils for the oligochaete Enchytraeus crypticus.

Current risk assessment procedures ignore that variation in soil properties results in substantial differences for uptake and effects in organisms in different soils. In this contribution is presented the results of a study on the soil-related factors that modulate metal uptake and elimination by the oligochaete worm Enchytraeus crypticus. Uptake of Cd, Cu, Pb, and Zn was quantified in 20 Dutch field soils as a function of time. Uptake rate constants and equilibrium concentrations were estimated using compartment modeling. Internal metal concentrations varied less than the corresponding external levels. Zn and especially Cu provided the most extreme examples of this general behavior, which suggests regulation by the organism. Body residues by Cd increased linearly over time in 11 of the 20 soils studied, whereas in the remaining 9 soils equilibration of internal Cd levels was observed. CaCl2 extraction could be used to discriminate the 9 soils in which there is Pb accumulation from the 11 soils in which bioavailable Pb levels were too low to allow for uptake. Multivariate expressions that describe uptake rate constants and bioaccumulation factors as a function of soil characteristics were derived. pH and cation exchange capacity were the most important parameters. The formulae were very similar to those describing partitioning of metals over the solid and liquid phase of the soils, which suggests pore water-mediated uptake. A semi-mechanistic approach yielded further evidence of pore water-related uptake, modulated by competition between H+ and metal ions at the active sites of the membranes.

Animals↗
PubMed1999

Relating environmental availability to bioavailability: soil-type-dependent metal accumulation in the oligochaete Eisenia andrei.

Body residues are often better estimates of the amount of a chemical at the sites of toxic action in an organism than ambient soil concentrations, because bioavailability differences among soils are explicitly taken into account in considerations of body residues. Often, however, insufficient attention is paid to the rate and extent at which tissue concentrations respond to soil concentrations and soil characteristics. In this contribution the impact of soil characteristics on the environmental bioavailability of heavy metals for the oligochaete worm Eisenia andrei is reported. Uptake of As, Cd, Cr, Cu, Ni, Pb, and Zn in 20 Dutch field soils and in OECD artificial soil was quantified as a function of time. Internal metal concentrations varied less than the corresponding external levels. Metal uptake and elimination were both metal- and species-dependent. Worms typically attained steady-state concentrations rapidly for Cr, Cu, Ni, and Zn. Internal concentrations similar to those in the cultivation medium, linearly increasing body concentrations, or steady-state internal concentrations well above those in the cultivation medium were found for As, Cd, and Pb. Multivariate expressions were derived to describe uptake rate constants, steady-state concentrations, and bioaccumulation factors as a function of soil characteristics. Soil acidity is the most important solid-phase characteristic modulating the availability of As, Cd, and Pb. Although additional semimechanistic calculations yielded evidence of pore-water-related uptake of Cd and Pb modulated by competition between H(+) and metal ions at the active sites of the membranes, the findings for Cr, Cu, Ni, and Zn point to additional influences, among which is probably regulation.

Animals↗
PubMed1998

[Contact allergy to eyedrops containing beta-blockers].

In six patients (4 women aged 80, 62, 43 and 52 years and 2 men aged 58 and 51 years), who used eyedrops containing beta-blockers for the treatment of glaucoma, allergic contact dermatitis of the eyelids was diagnosed. Three were allergic to metipranolol, 2 to levobunolol and 1 to timolol. In literature, less than 50 cases of hypersensitivity to beta-blockers in eye medication have been reported. There are, however, reasons to assume that sensitization is more frequent: (a) not all patients are referred by the ophthalmologist to the dermatologist; (b) false-negative reactions to patch tests with the commercial preparations and with beta-blockers are not infrequent; (c) they are not routinely tested because beta-blockers are difficult to obtain in pure form; (d) cross-reactions with other beta-blockers are infrequent, and changing to another preparation therefore usually solves the clinical problem. Nevertheless it is advisable to test a battery of beta-blockers (befunolol, levobunolol, metipranolol, timolol) in allergic patients. A test preparation of 2% in water or 3%-10% in petrolatum may be suitable. Control testing in non-exposed individuals is necessary to exclude irritation reactions.

Adrenergic beta-Antagonists↗
PubMed1997

[Statement of ingredients of cosmetics].

Since January 1st 1997 there is European legislation labelling that cosmetic products are supplied with a list of their ingredients. The ingredients are given in order of decreasing concentration using the nomenclature 'International nomenclature cosmetic ingredient' (INCI). This enables dermatologists to identify the allergenic components of cosmetic products in patients with allergic contact dermatitis caused by cosmetics, and enables allergic patients to purchase other cosmetic products without risking a recurrence of dermatitis.

Cosmetics↗
PubMed1997

[Contact allergy for corticosteroids].

Contact allergy to corticosteroids is not rare. In some studies prevalence rates up to 6% have been observed among patients suspected of allergic contact dermatitis. Hypersensitivity occurs especially in individuals who have been suffering for years from atopic dermatitis, contact dermatitis of the hands and feet, or stasis dermatitis caused by chronic venous insufficiency. The clinical picture is rarely that of acute allergic contact dermatitis, because the reaction is mitigated by the anti-inflammatory properties of the corticosteroid itself; the diagnosis must be suspected when eczema does not improve or spreads during topical corticosteroid therapy. Application to the mucous membranes less frequently leads to sensitisation. Most such cases are caused by nasal sprays containing tixocortol pivalate or budesonide. Oral or parenteral administration of corticosteroids to sensitive individuals causes exacerbation of pre-existing contact dermatitis or widespread allergic cutaneous drug reactions. Allergological investigation with corticosteroids presents some specific problems, the most important being occurrence of false-negative reactions. Nevertheless, most sensitive patients can be identified by testing the 'indicator' allergens, budesonide and tixocortol pivalate, which should be added to the routine series of contact allergens. Cross-reactions to other corticosteroids occur frequently. This should be taken into account when prescribing alternative corticosteroid preparations.

Administration, Topical↗
PubMed1997

[Contact allergy for perfume ingredients in cosmetics and toilet articles].

Fragrance materials are not only present in products primarily used for their scent such as perfume, eau de toilette, deodorant and aftershave, but also in cosmetics, toiletries, household products and industrial materials. Of the general population, approximately one percent are allergic to fragrance materials, men nearly as frequent as women. Of patients consulting the dermatologist because of dermatitis, 6-11% have a positive patch test to the fragrance mix. Allergic contact dermatitis due to fragrances usually consists of erythema and desquamation, often localized in the neck, behind the ears, in the arm-pits or around the eyes. It can worsen pre-existing dermatoses such as hand eczema, atopic dermatitis, perianal dermatitis or vulvar dermatitis. The diagnosis of contact allergy to fragrances is made by epicutaneous tests with the European standard series (including some markers for fragrance sensitivity: the fragrance mix, balsam of Peru and colophony) and the patient's own contact materials. A positive patch test reaction must be followed by evaluation of its relevance. Advice to the patient is directed towards avoidance of fragranced products, if possible, and explanation of how use tests can identify fragranced products which can be used without ill effects.

Cosmetics↗
PubMed1997

Conversion of common names of cosmetic allergens to the INCI nomenclature.

We have made a list of substances that can be present in cosmetics and have been described as allergens, and compared their formerly more familiar names with International Nomenclature Cosmetic Ingredient (INCI) nomenclature, when different. The list should assist dermatologists in advising their patients allergic to cosmetic ingredients.

Allergens↗
PubMed1997

Adverse reactions to fragrances. A clinical review.

This article reviews side-effects of fragrance materials present in cosmetics with emphasis on clinical aspects: epidemiology, types of adverse reactions, clinical picture, diagnostic procedures, and the sensitizers. Considering the ubiquitous occurrence of fragrance materials, the risk of side-effects is small. In absolute numbers, however, fragrance allergy is common, affecting approximately 1% of the general population. Although a detailed profile of patients sensitized to fragrances needs to be elucidated, common features of contact allergy are: axillary dermatitis, dermatitis of the face (including the eyelids) and neck, well-circumscribed patches in areas of "dabbing-on" perfumes (wrists, behind the ears) and (aggravation of) hand eczema. Depending on the degree of sensitivity, the severity of dermatitis may range from mild to severe with dissemination and even erythroderma. Airborne or "connubial" contact dermatitis should always be suspected. Other less frequent adverse reactions to fragrances are photocontact dermatitis, immediate contact reactions and pigmentary changes. The fragrance mix, although very useful for the detection of sensitive patients, both causes false-positive and false-negative reactions, and detects only 70% of perfume-allergic patients. Therefore, future research should be directed at increasing the sensitivity and the specificity of the mix. Relevance is said to be established in 50-65% of positive reactions, but accurate criteria are needed. Suggestions are made for large-scale investigation of several fragrances on the basis of literature data and frequency of use in cosmetics. The literature on adverse reactions to balsam of Peru (an indicator for fragrance sensitivity), essential oils (which currently appear to be used more in aromatherapy than in perfumery) and on fragrances used as flavours and spices in foods and beverages is not discussed in detail, but pertinent side-effects data are tabulated and relevant literature is provided.

Cosmetics↗
PubMed1996

Methyldibromoglutaronitrile is an important contact allergen in The Netherlands.

From 15 May to 15 December 1994, 2943 patients suspected of having contact dermatitis (1955 women, 988 men) were patch tested with methyldibromoglutaronitrile 0.3%, 0.1% and 0.05% pet. 119 patients (4.0%; women 4.1%, men 3.8%) proved to be allergic. 71% of the reactions were considered to be relevant. In 2/3 of the patients, causative products were cosmetics, in 1/3 moistened toilet tissues. Testing with methyldibromoglutaronitrile at lower concentrations (0.05% and 0.1%) and with commercial allergens (Euxyl K 400 and methyldibromoglutaronitrile, both containing methyldibromoglutaronitrile 0.1%), resulted in a number of false-negative reactions. All preservatives in the European standard series had lower scores than the 4% positive reactions to methyldibromoglutaronitrile (formaldehyde 2.0%, MCI/MI (Kathon CG) 3.2%, parabens 1.0%, quaternium-15 1.3%). It is concluded that methyldibromoglutaronitrile (present in the commercial preservative Euxyl K 400) is an important contact allergen in the Netherlands in cosmetics and moistened toilet tissues. It should be added to cosmetics series and to proctological series. The optimal test concentration is unknow, but may be 0.3% pet. The concentration of 0.1% methyldibromoglutaronitrile in the currently available commercial allergens appears to be too low, resulting in a number of false-negative reactions.

Adolescent↗