Search PubMed⌕ Search

Biomedical subjects

H Merk

Publications and source records attributed to H Merk.

At least 55 records · Page 3Linked to original sources
PubMed1997

Molecular basis of variegate porphyria: a de novo insertion mutation in the protoporphyrinogen oxidase gene.

The porphyrias are disorders that result from the inherited or acquired dysregulation of one of the eight enzymes in the heme biosynthetic pathway. Variegate porphyria (VP) is characterized by deficiencies in protoporphyrinogen oxidase (PPO) and has recently been genetically linked (Z = 6.62) to the PPO gene on chromosome 1q21. In this study, we have identified two sequence variants in the PPO gene in a family with VP. The first is a neutral polymorphism at the -47 position of intron 2; this polymorphism is present in the general population and is unlikely to underlie the VP phenotype. The second is a mutation in the PPO gene in a patient with VP; the mutation consists of an apparently de novo 2-bp insertion in exon 3 of PPO and results in a frameshift and downstream premature termination codon. These data establish that a frameshift mutation in PPO is the underlying mutation in this patient with VP and explain the sporadic occurrence of the phenotype in this family.

Adult↗
PubMed1997

[Ultrasound findings of the patellar tendon and its insertion sites].

PURPOSE: To examine the use of ultrasonography in the diagnosis of soft tissue lesions in and around the patellar tendon. MATERIAL AND METHODS: We analysed the sonograms of 87 patients with knee pain and patellar tendon lesions after clinical observation. We used a 7.5 MHz linear scanner. In cases of bone lesions, a roentgenologic examination was performed. RESULTS: The visualisation of pathologic findings of the patellar tendon such as focal or generalised thickenings, calcifications as well as partial or total ruptures is possible with ultrasound. We could classify six different sonopathologic stages of the jumper's knee syndrome. In addition patellar bursitis and aseptic necrosis of the patella and tibial tuberosity can be identified. CONCLUSIONS: Ultrasound examination is a noninvasive, time sparing and economical diagnostic tool to evaluate chronic patellar tendinitis, to plan therapy and to objectively assess the results of treatment.

Athletic Injuries↗
PubMed1997

[Ultrasound follow-up after surgically managed Achilles tendon ruptures].

PURPOSE: To evaluate surgically repaired ruptures of the Achilles tendon by means of ultrasonography, employing the classification scheme of Thermann et al. METHOD: 54 patients were examined by ultrasonography after an average interval of 4.4 years. A 7.5 MHz linear transducer was used with a gel approach piece to evaluate the longitudinal and transverse images of the tendon. RESULTS: More than 90% of patients AHD Grade 2 or 3 tendons; in only 3 patients could the repaired tendon be designated Grade 1 or comparable to the healthy control. CONCLUSION: There was no correlation between the relatively unsatisfactory results seen on ultrasonography and the clinical results. We cannot recommend ultrasonography as the only method for assessing postoperative results following Achilles tendon repairs.

Achilles Tendon↗
PubMed1997

[Gray scale histographic analysis of the acetabular cartilage for quantifying hip ultrasound images].

AIM: Congenital dislocated hips are classified in ultrasound studies using the angle measuring system of Graf and evaluating the typical changes in acetabular form and structure. We attempted to quantify physiological and pathological changes in the acetabular cartilage using B-mode scan ultrasound studies. METHODS: Gray-level histograms were performed on 894 infant hips; 833 were classified by the Graf scheme as Type IIa and 61 as Type IIIa/b. We compared the histological structure of the cartilage of both the acetabulum and the head of the femur using objective parameters. RESULTS: We could show that gray-level histograms of the acetabular cartilage are an ideal way to study objectively ultrasound evaluations of the same area. Type IIa hips with histographically identified ossification zones show significantly higher healing rates than those without such areas. Type IIIb hips with histographically demonstrated pathological changes showed a significantly longer healing rate and a higher incidence of persistent dislocations that did Type IIa hips with normal cartilage. CONCLUSION: Structural changes in the acetabular cartilage can be evaluated not only qualitatively but also quantitatively to provide prognostic information in infants with congenially dislocated hips. Gray-level histograms nicely supplement ultrasound examination.

Acetabulum↗
PubMed1997

[Treatment of recurrent traumatic shoulder dislocations with coracoid transfer--Latarjet-Bristow operation].

We reviewed 31 patients with recurrent traumatic anterior shoulder dislocations, being operated with the Latarjet-Bristow procedure consecutively between March 1991 and March 1994. The average follow-up time was 31.2 months. According to the Rowe-score results were estimated as excellent in 45.1% and as good in 38.7%. New shoulder dislocations occurred in one case, resulting in a new shoulder dislocation rate of 3.2 per cent. Deficits in the external rotation of more than 5 degrees compared with the not operated side were seen in 15 patients. In two patients 7 respectively 9 months after the operation loosenings of the screws happened, but were without any effect on the functional outcome of the operation. The Latarjet-Bristow procedure proved to be a very safe method with a low redislocation rate, few complications and good functional results. Because of limitations in external rotation, however, this method should only be performed in cases in which an anatomic labrum reconstruction is hardly possible.

Adolescent↗
PubMed1996

[A new score for comparing outcome of surgical management of Achilles tendon ruptures].

From January 1987 to March 1994 three hospitals in the city of Magdeburg treated a total of 103 subcutaneous Achilles tendon ruptures operatively. We created a special score to compare the outcome of the different operation techniques used. Important aspects of the follow-up examination were isokinetic measuring of power and staying power by means of a KIN-TREX dynamic measuring device and the clinical check-up in comparison with the histological results and the patients' history. Degeneration could only be proved histologically in 38,8% of the cases. The average score of all OP methods applied was 767 of possible 1000 points. The adaptation suture (781 points), Silfverskiold's technique (772 points) and the fibrin adhesive technique (754 points) showed approximately the same results. The theory that all of the ruptures have a histological degeneration background seems to be wrong. Isokinetic measuring can be very helpful in preparing a postoperative regimen to find the optimum load.

Achilles Tendon↗
PubMed1995

Perioperative train-of-four monitoring and residual curarization.

It has been suggested that perioperative train-of-four (TOF) monitoring does not reduce the incidence of postoperative residual curarization (PORC). The purpose of this study was to examine whether the use of tactile assessment of the response of the adductor pollicis to supramaximal TOF stimulation of the ulnar nerve at the wrist during anaesthesia affected the incidence of PORC. Thirty-nine ASA I or II surgical patients were studied during thiopentone/fentanyl N2O/enflurane anaesthesia. Pancuronium (70-100 micrograms.kg-1) was used to facilitate tracheal intubation and additional pancuronium increments used to maintain surgical relaxation. The requirement for incremental doses of pancuronium and adequacy of recovery following reversal were assessed according to random allocation, either with (Group A; n = 20) or without (Group B; n = 19) access to TOF monitoring. Patients in the two groups received neostigmine in similar doses (Group A: 53 micrograms.kg-1 (5.9); Group B: 55 micrograms.kg-1 (5.4)). On arrival of the patient to the recovery area, neuromuscular function was assessed electromyographically (using the Datex NMT 221 to measure TOF ratio) and clinically. The incidence of PORC (TOF ratio < 70%) was greater in Group B (47%) than in Group A (15%) (P = 0.029). We conclude that the use of perioperative TOF monitoring decreases the incidence of pancuronium-induced PORC.

Adult↗
PubMed1995

Isolation and characterization of allergen-binding cells from normal and allergic donors.

BACKGROUND: Flow cytometry of the immune system so far has been limited to the analysis of subpopulations according to lineage markers. The cells involved in a particular immune response could not be assayed due to their low frequency. Here we show the potential of antigen-specific high gradient magnetic cell sorting to enrich cells for visualisation in multiparameter cytometry, functional studies and immortalization. OBJECTIVES: The aim of this study was the development of an efficient technology for staining and isolation of antigen-binding cells from human peripheral blood. In particular, allergen-specific cells from normal and allergic donors should be analysed and compared to develop a cellular diagnosis of allergy. STUDY DESIGN: The rare antigen-specific cells were sorted by high-gradient magnetic cell sorting with MACS. Haptenized phospholipase A2 (PLA2), the major allergen of bee venom, or haptenized ParoI, the major allergenic component of Parietaria officinalis, were used as antigens. The cells from normal and allergic donors, binding to the allergen were characterized phenotypically by immuno-fluorescence. Allergen-specific B-cells were immortalized by EBV transformation. RESULTS AND CONCLUSION: Allergen-specific cells can be enriched from blood of both allergic and normal donors to purities of up to 75%, by high gradient magnetic cell sorting. The specificity of labelling with allergen was confirmed by establishing allergen-specific EBV-transformed B-cell lines from the sorted cells. Clear differences exist in the cellular composition of allergen-binding cells from normal compared to allergic donors. In normal donors the allergen-binding cells are B-cells expressing CD19 and CD21. In allergic donors, in addition to allergen-binding B-cells, occurring in about equal absolute numbers as in normal donors, basophilic granulocytes are labeled by allergen. These cells express CD38, CD9 and CD25 on their surface, and stain for IgE.

Allergens↗
PubMed1994

[Anticonvulsant hypersensitivity syndrome to carbamazepine].

In a 39-year-old woman an anticonvulsant therapy was initiated because of focal attacks in the left arm and face. The patient experienced generalized maculopapular skin rashes in response to each of four chemically similar anticonvulsant drugs: phenytoin, carbamazepine, primidone and clonazepam. During administration of carbamazepine the clinical features included fever, hepatitis and hematological eosinophilia in addition to the skin rash (anticonvulsant hypersensitivity syndrome). The anticonvulsant hypersensitivity syndrome is defined as an idiosyncratic reaction caused by disturbed drug metabolism. Positive lymphocyte-transformation tests with carbamazepine and phenytoin indicate an immunological mechanism underlying the rashes in our patient. Patch testing with the four anticonvulsant drugs gave positive results only with carbamazepine. Skin biopsy showed the histological features of a delayed-type allergy. The anticonvulsant therapy was continued with a chemically unrelated preparation, valproic acid; this drug is well tolerated and has proved appropriate for prevention of seizures.

Adult↗
PubMed1993

The effects of heparin and annexin V on fibrin accretion after injury in the jugular veins of rabbits.

We compared the relative abilities of unfractionated heparin and annexin V to prevent fibrin accretion onto injured jugular veins in vivo. Heparin was used to accelerate the inhibition of thrombin by antithrombin III, and annexin V was used to inhibit the assembly of the prothrombinase complex on phospholipid surfaces, thereby blocking thrombin generation. Rabbit jugular veins were isolated in situ, a 2 cm segment was injured by perfusing it with air, and then blood flow was re-established. Five minutes later, each rabbit was injected with heparin (20 U/kg) or annexin V (0.3 mg/kg) and then with 125I-fibrinogen. The amount of 125I-fibrin accumulation onto each injured vessel wall segment was measured 4 h later. Each injured vessel was completely de-endothelialized as a result of the air perfusion as demonstrated by electron microscopy. 125I-fibrin accretion onto the injured jugular veins was enhanced 2.4-fold as compared to the uninjured veins in sham-operated animals. Heparin treatment did not reduce fibrin accretion, whereas, annexin V treatment decreased fibrin accretion by 60%, p < 0.05. This latter effect was achieved without sustained circulating anticoagulation. Additional experiments confirmed that the inhibitory effect of annexin V on fibrin accretion was associated with a surface specific effect, since more annexin V bound to the injured jugular vein segments as compared to the non-injured jugular veins.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Adverse immune reactions to gold in rheumatoid arthritis: lack of skin reactivity.

Adverse immune reactions develop in up to 30% of patients treated with gold compounds. However, sensitization to gold(I) drugs is rarely demonstrated by in vivo or in vitro testing. Recent data from a mouse model provides evidence that gold(I) is oxidized to gold(III) before T cells are sensitized. To study the diagnostic value of skin tests, patch testing with various gold compounds - including gold(I) and gold(III) - was performed in 50 patients with rheumatoid arthritis treated with gold(I) drugs. Positive patch test reactions to either gold(I) or gold(III) compounds were not detected. In contrast, the lymphocyte transformation test (LTT) revealed a gold(III)-induced response in one of the 7 patients being tested. We conclude that patch testing fails to indicate T cell sensitization to gold(I) drugs in rheumatoid arthritis patients. The in vitro response to gold(III) obtained by LTT supports the hypothesis that biooxidation of gold(I) compounds may play a crucial role for sensitization.

Arthritis, Rheumatoid↗
PubMed1992

[The effect of foreign-substance-metabolizing enzymes on skin diseases].

Multiple drug-metabolizing enzymes are located in the skin of animals and humans: cytochrome P-450, epoxide hydrases, transferases and reductases. The distribution of cytochrome P-450 in the skin is not homogeneous; rather, it is more active in the basal epidermis, keratinocytes of the hair follicle, and sebaceous cells. The activity of drug-metabolizing enzyme can be induced, but it can also be inhibited by multiple endogenous and exogenous compounds. These enzymes detoxify many xenobiotics, but if the balance is disturbed there is the risk that xenobiotics will be activated to highly toxic compounds, which are even involved in the pathogenesis of skin cancer. Recent results indicate that cytochrome P-450 isoenzymes are also involved in the pathogenesis of psoriasis and drug-induced skin diseases.

Animals↗
PubMed1991

Induction and inhibition of NAD(P)H: quinone reductase in murine and human skin.

The purpose of this study was to characterize the human cutaneous NAD(P)H: quinone reductase (NQR) activity by known inhibitors of different reductases and to compare it with the murine skin and liver NQR activity. This enzyme plays a major role in the defence of cells against oxygen stress because it inhibits the 1-electron reduction of quinones to semiquinones and their subsequent oxidation to quinones termed as quinone redox cycle. It belongs to the aromatic hydrocarbon-responsive (Ah) battery. This gene battery includes Cyp1a1 (cytochrome P-450 IA1), Cyp1a2 (cytochrome P-450 IA2) and Nmo-1 [NAD(P)H: quinone reductase]. In the skin cytochrome P-450 IA1-dependent activity is about 1-5% compared to the corresponding activity in the liver, whereas NQR has the same activity in skin and liver. NQR was determined in the cytoplasm of murine skin, liver, and human keratinocytes using 2,6-dichlorophenolindophenol as the substrate. The Ah-receptor binding compounds, such as coal tar constituents, or 3-methylcholanthrene induce cytochrome P-450-dependent activities such as aryl hydrocarbon hydroxylase or 7-ethoxyresorufin-O-de-ethylase and NQR, whereas butyl hydroxytoluol, which does not bind to the Ah receptor, induces only NQR. For inhibition studies several known inhibitors of dihydrodiol dehydrogenase, aldo-keto and carbonyl reductase activities were used. There was a similar pattern of inhibition of the basal and induced activity in all tissues investigated. Pyrazole, progesterone and phenobarbital did not inhibit, whereas dicoumarol, rutin and indomethacin inhibited NQR activity in murine skin and liver as well as in human keratinocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗