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Biomedical subjects

B B Knudsen

Publications and source records attributed to B B Knudsen.

At least 19 recordsLinked to original sources
PubMed2000

Allergologically relevant rubber accelerators in single-use medical gloves.

To prevent contact with specific rubber accelerators, sensitized patients have to know in which glove brands these accelerators are present. Additionally, quantitative measurements of the bioavailable amounts of accelerators are needed to assist consumers in selecting gloves with the lowest possible amount of residual rubber accelerators. The aim of the study was to develop an analytical method by which residuals of rubber accelerators in single-use medical gloves could be determined qualitatively and quantitatively. 19 different glove brands were analysed for content of accelerators, and the results were compared to manufacturers' ingredient claims of the identical gloves. ZDEC, ZDBC, ZMBT and ZPC were the most frequently detected chemicals. In 9 of 15 gloves discrepancies were found, usually minor, between content of accelerators declared by manufacturers to be present and accelerators detected by analysis. Both phosphate buffer and acetone were tested as extraction media. No accelerators were detectable with the described chemical analysis in phosphate extracts, whereas acetone was demonstrated to be a technically suitable medium for extraction. However, more kinetic studies of the extraction procedure and studies of skin penetration are needed to document that the extraction procedure simulates the clinical situation.

Allergens↗
PubMed1999

[Latex allergy diagnosed at a department of dermatology. A descriptive analysis of a 3-year material].

This study gives a descriptive analysis of 52 patients with type-I allergy to latex. Seventy-one percent of these cases were considered occupational, especially related to the health care sector (29 of 37 patients). Four patients had to change their jobs because of the allergy. Twenty-five percent presented initially with monosymptomatic contact urticaria, while 35% presented with hand eczema, which could only be explained by concomitant allergy to rubber chemicals in 35% of the cases. During the period from observation of initial symptoms until establishment of the diagnosis, several of the patients with monosymptomatic hand eczema developed additional type-I related symptoms. Not only latex-exposed patients with type-I-related symptoms, but also latex-exposed patients with hand eczema should be suspected for latex-allergy and tested with pricktests, latex-specific IgE and skin-provocation tests.

Denmark↗
PubMed1996

Elicitation thresholds for thiuram mix using petrolatum and ethanol/sweat as vehicles.

An estimate of amounts of thiurams that may be released from rubber gloves into synthetic sweat, has previously been generated. These amounts should be compared to elicitation thresholds of patch tests performed with serial dilutions of thiuram mix using synthetic sweat as vehicle. Because of solubility properties of thiurams in aqueous media, such dilutions cannot directly be prepared. In this study, a stem solution was prepared in ethanol. This solution was then further diluted with synthetic sweat. Thiuram mix 0.5 w/v% was the most concentrated solution in ethanol achievable. The patch test reactions were compared to reactions to serial dilutions using petrolatum as vehicle. The experiment revealed that endpoint dilution with synthetic sweat was not achieved in this study. The threshold for elicitation of positive patch test reactions seemed to be lower for ethanol/sweat as vehicle compared to petrolatum: 32% reacted to ethanol/synthetic sweat 0.001 mg/cm2 compared to 14% reacting to thiuram in pet. 0.002 mg/cm2. Based on these results, synthetic sweat may be considered a more relevant medium for threshold finding studies than petrolatum. Because of expected instability of the aqueous solutions, petrolatum is probably a more suitable vehicle for routine testing. The study does not permit final conclusions concerning acceptable thresholds for leachable thiurams in rubber gloves, but it is likely that an acceptable threshold would be substantially less than 0.001 mg/ cm2.

Allergens↗
PubMed1996

Contact allergy and exposure patterns to thiurams and carbamates in consecutive patients.

Sensitization to rubber is most often due to sensitization to thiurams. Positive patch test reactions to carbamates are less frequent, and usually only diagnosed in patients with positive patch test reactions to thiurams as well. The aim of the present study was to describe the relative frequency of sensitization to thiuram mix (TH mix) and zinc diethyldithiocarbamate (ZDC) in a population where the exposure to these chemicals from rubber gloves was previously studied and considered to be of approximately the same order of magnitude. The thiuram derivatives seemed to be the most important sensitized (frequency 2.8%) compared to ZDC (frequency 0.5%), which has been the most frequently reported sensitizer among the carbamates in rubber gloves. An interesting observation was that the probability that the patient was reacting to ZDC was strongly associated with the strength of the patch test reaction to TH mix. This observation may add a new aspect to the discussion about cross-reactivity versus concomitant sensitization of thiurams and carbamates.

Carbamates↗
PubMed1995

[Allergy to natural rubber. A current problem].

Three cases of immediate type hypersensitivity to natural rubber latex are described. Unexpected, severe reactions were seen in two patients. One patient had used rubber gloves regularly and experienced moderate local symptoms. She had to change job because of generalised urticaria and asthma due to airborne latex-allergens in the workplace. The diagnosis of latex allergy may not always be obvious, and negative or weak IgE-RAST can be seen in patients who have experienced severe allergic reactions after latex exposure. Cross reactions to banana, avocado, kiwi and possibly other fruits and plants may be seen. Medical staff using latex gloves should be aware of the risk of severe adverse reactions in their patients due to latex allergy. Gloves made from vinyl or other synthetic materials (i.e. Elastyren or Tactylon) can be used in these cases.

Adult↗
PubMed1993

Release of thiurams and carbamates from rubber gloves.

A method for quantitative determination of thiuram and carbamate derivatives released from rubber gloves into synthetic sweat is presented. The analysis was based upon determination of ester derivatives using gas-chromatography/mass spectrometry and isotope-dilution. The detection limit was 0.1 mg thiuram/carbamate in 200 ml synthetic sweat (0.5 ppm). The release of thiurams and carbamates from 5 household and 5 surgical types of gloves into synthetic sweat was determined. Each of the natural rubber gloves released varying amounts of thiurams (0-4.3 mg) as well as carbamates (0-8.1 mg). 22 thiuram-sensitized patients were patch tested with pieces of the gloves. Gloves releasing considerable amounts of thiurams and/or carbamates seemed to cause more positive patch test reactions in these patients than gloves releasing smaller amounts. Surgical gloves made from natural rubber caused a substantial larger number of positive patch test reactions than household gloves made from natural rubber. The amounts released per cm2 of the gloves were of the same order of magnitude as the content per cm2 patch test of thiuram mix, diluted 1:10. The accessibility of a quantitative, chemical analysis for thiurams and carbamates released from rubber gloves makes it reasonable to ask for declarations of rubber gloves. Proposals for threshold values for release of thiurams and carbamates from rubber gloves may be given in the future.

Carbamates↗
PubMed1992

[Allergy and other skin reactions as a result of rubber gloves].

Protective latex surgical gloves and examination gloves may cause allergic contact dermatitis, mainly due to rubber chemicals used in the manufacturing process. Latex proteins in the gloves may cause contact urticaria and even anaphylactoid reactions. Eighty-eight dentists and other members of the dental team were tested for contact allergy to thiuram- and mercapto-derivatives, and for contact-urticaria to latex proteins. All but 5 persons used gloves at least periodically. Fifty-one of 87 of the persons who answered a questionnaire had or had had symptoms from the skin on the hands, but in only 3 cases could allergy to the gloves be proved. Women had more often symptoms than men, and female dentists with symptoms used gloves more often and for longer periods than female dentists without symptoms. It can be concluded that redness of the skin, itching, vesicles and eczema are common symptoms reported in connection with use of gloves, but proved allergy to the gloves is rare. Most symptoms are supposed to be due to skin irritation from the gloves in addition to irritative exposure from handwashing and other chemical irritants in dental work. The nature of the irritative effect from gloves is only partly known and should be studied further.

Dentists↗
PubMed1991

Chlorhexidine gluconate and acetate in patch testing.

Patch testing to chlorhexidine is usually performed with chlorhexidine gluconate aq. We report the results of 297 patients, almost all with leg ulcers, concomitantly tested with chlorhexidine acetate 1% aq. and chlorhexidine gluconate 1% aq. 39 patients had positive reactions to one of these compounds or to both. 36 positive reactions to the acetate were found, in contrast to 18 reactions to the gluconate. The reactions were considered relevant in 22 of 39 patients, since these patients had developed an eczema in an area where a chlorhexidine compound was used, and discontinuing the chlorhexidine compound resulted in improvement of the condition. In 10 of these 22 patients, the diagnosis would have been missed if the gluconate only had been used for testing, while the acetate failed to diagnose 2 patients. In 109 patients without leg ulcers, inconclusive patch test readings (i.e., irritant reactions or weak positive reactions) were found in 17% with chlorhexidine acetate 1% aq., compared to 5% with chlorhexidine gluconate 1% aq., indicating a high degree of irritant potential of the acetate 1% aq. We consider that some positive reactions are lost if chlorhexidine gluconate 1% aq. only is used for patch testing, but that chlorhexidine acetate 1% aq., on the other hand, is an unacceptably strong irritant. We therefore suggest that further testing with chlorhexidine acetate 1 and 0.5% aq. should be performed, in parallel with chlorhexidine gluconate 1% aq., in order to establish appropriate test concentrations. We find that up to 13% of the leg ulcer patients in this study may be sensitized to chlorhexidine, and we recommend that the indications for the drug in leg ulcer patients should be reconsidered.

Chlorhexidine↗
PubMed1990

[Kathon CG--a new contact sensitizing preservative].

Kathon CG is a preservative, widely used in skin care products and cosmetics. Prior to introduction to the market, extensive studies on the sensitizing potential of this product were performed. The conclusion drawn from these studies was, that the risk of sensitization was extremely small, when used in concentrations below 15 ppm. Now, ten years later, the frequency of allergy to Kathon CG is 1-2% in the Danish population, which is in the same range as the frequencies for the other preservatives. It is concluded, that the preliminary studies were insufficient and monitoring of the prevalence rates of sensitization is important, when new potential sensitizers are introduced. A total ban on the isothiazolinone derivates from the cosmetics, will only transfer the problem to the other preservatives already known as sensitizers. It might be technically acceptable to lower the concentrations further. Since the cosmetic products are not declared, a correct diagnose may be delayed or missed in patients with eczema. Ingredient labelling should be required by the authorities.

Adult↗
PubMed1989

[Penicillin allergy. Provocation in patients with suspected penicillin allergy].

In 61 patients, all Penicilloyl-RAST-negative and with histories of possible allergy to penicillins, a testing procedure to detect penicillin allergy was performed. Sixteen of the patients reacted to the challenge. No serious reactions were registered, although one patient developed an extensive local reaction several hours after intracutaneous application. The testing procedure is considered safe for the patient, if extreme dilutions are used primarily, sufficient observation time is allowed and equipment for treating possible anaphylactic reactions is available. The procedure should be performed in selected patients only. Information about the primary reaction was not useful as a diagnostic parameter for allergic reactions.

Allergens↗
PubMed1987

Influence of ethanol on development of hyperplastic nodules in alcoholic men with micronodular cirrhosis.

The type of cirrhosis was blindly evaluated in follow-up liver biopsies performed on 106 alcoholic men with micronodular cirrhosis. The median time interval from entry to follow-up liver biopsy was 31 mo (range, 3-44 mo). Patients were stratified into four groups according to their maximal registered ethanol consumption during follow-up. Thirty-six patients (34%) abstained from ethanol, 40 patients (38%) consumed a small amount of ethanol (less than 50 g/day), 19 patients (18%) consumed a moderate amount of ethanol (51-100 g/day), and 11 patients (10%) consumed an excessive amount of ethanol (greater than 100 g/day) during follow-up. Follow-up liver biopsy specimens demonstrated micronodular cirrhosis in 54 patients (51%), micronodular cirrhosis with development of hyperplastic nodules in 47 patients (44%), and nonclassifiable macronodular cirrhosis in 4 patients (4%); 1 patient showed portal fibrosis. The cumulative prevalence of patients developing hyperplastic nodules increased significantly (p = 0.014 for trend) with decreasing ethanol consumption, the prevalence being 57% in abstainers, 58% in those who consumed a small amount of ethanol, 32% in those who consumed a moderate amount, and 18% in those who consumed an excessive amount. In conclusion, alcoholic men with micronodular cirrhosis develop hyperplastic nodules during follow-up, the rate and prevalence of which is significantly related to the amount of ethanol consumed during follow-up. Ethanol consumption may inhibit hepatocellular proliferation in alcoholic men with micronodular cirrhosis.

Adult↗
PubMed1987

No effect of long-term oral testosterone treatment on liver morphology in men with alcoholic cirrhosis.

The effect of oral testosterone treatment (200 mg tid) on liver morphology was examined in a double-blind, placebo controlled study including men with alcoholic cirrhosis (n = 126). Liver biopsies obtained before randomization showed micronodular cirrhosis in 119 patients (94%), alcoholic hepatitis in 64 (51%), and fatty liver in 104 (83%). These and other morphological findings did not differ significantly in the patients randomized to testosterone (n = 76) and to placebo (n = 50) (skewed randomization 3:2). Follow-up liver specimens (biopsies or autopsies) obtained after a median treatment duration of 30 months demonstrated a significant (p less than 0.01) increase in the prevalence of macronodular cirrhosis (from 6 to 51%) and a significant (p less than 0.01) decrease in the prevalence of alcoholic hepatitis (to 21%) and of fatty liver (to 52%). Testosterone treatment did not significantly influence the prevalence of these changes. Further, testosterone treatment had no significant effect on the prevalence of other morphological changes, including vascular and malignant changes. However, in the testosterone-treated group one patient developed diffuse sinusoidal dilation and one patient showed Budd-Chiari's syndrome. The degree of fatty liver and of alcoholic hepatitis in follow-up liver specimens were significantly (p less than 0.002) higher among patients who consumed ethanol during follow-up than in patients who abstained (76 versus 22% and 30 versus 6%). In conclusion, this study does not establish any indication or any contraindication in terms of hepatic histopathology with the possible exception of hepatic venous thrombosis for the use of oral testosterone treatment in men with alcoholic cirrhosis.

Biopsy↗