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Biomedical subjects

H Walt

Publications and source records attributed to H Walt.

At least 19 recordsLinked to original sources
PubMed2005

Early neoplastic and metastatic mammary tumours of transgenic mice detected by 5-aminolevulinic acid-stimulated protoporphyrin IX accumulation.

A photodynamic technique for human breast cancer detection founded upon the ability of tumour cells to rapidly accumulate the fluorescent product protoporphyrin IX (PpIX) has been applied to transgenic mouse models of mammary tumorigenesis. A major goal of this investigation was to determine whether mouse mammary tumours are reliable models of human disease in terms of PpIX accumulation, for future mechanistic and therapeutic studies. The haeme substrate 5-aminolevulinic acid (5-ALA) (200 mg kg(-1)) was administered to mouse strains that develop mammary tumours of various histological subtypes upon expression of the transgenic oncogenes HRAS, Polyoma Virus middle T antigen, or Simian Virus 40 large T antigen in the mammary gland. Early neoplastic lesions, primary tumours and metastases showed consistent and rapid PpIX accumulation compared to the normal surrounding tissues, as evidenced by red fluorescence (635 nm) when the tumours were directly illuminated with blue light (380-440 nm). Detection of mouse mammary tumours at the stage of ductal carcinoma in situ by red fluorescence emissions suggests that enhanced PpIX synthesis is a good marker for early tumorigenic processes in the mammary gland. We propose the mouse models provide an ideal experimental system for further investigation of the early diagnostic and therapeutic potential of 5-ALA-stimulated PpIX accumulation in human breast cancer patients.

Aminolevulinic Acid↗
PubMed2004

Photodynamic detection of diseased axillary sentinel lymph node after oral application of aminolevulinic acid in patients with breast cancer.

Benign as well as malignant tumour tissues of the breast demonstrate higher fluorescence intensity (FI) than normal breast tissue after application of a photosensitiser. As a follow-up study, we evaluated the FI of metastatic sentinel lymph nodes and metastatic axillary lymph nodes compared to nonmetastatic sentinel and axillary lymph nodes in patients with breast cancer. In all, 11 patients received 30 mg 5-aminolevulinic acid (ALA) kg(-1) bodyweight orally 3 h prior to surgery. The sentinel lymph node was marked with Nanocoll preoperatively and with a blue dye intraoperatively. Tumour excision, excision of the sentinel lymph node and an axillary lymph node dissection were performed during the same surgical session. The operation site was illuminated with blue light (400 nm) to obtain macroscopic tissue characterisation of fluorescence. Tissue samples were stored protected from light, and analysed using a fluorescence microscope. Results were correlated with histopathology. In all, 14 sentinel lymph nodes, seven axillary lymph nodes and seven primary tumours were analysed. Metastatic sentinel lymph nodes demonstrated a statistically significant higher FI than nonmetastatic sentinel lymph nodes (2630 vs 526, P<0.0001). The FI of metastatic sentinel lymph nodes, of metastatic axillary lymph nodes and of the primary tumour were comparably high, and were statistically significantly higher compared to the normal mammary tissue. Intraoperatively, only in a few cases, it was possible to recognise the metastatic sentinel lymph node macroscopically with blue light. Our study indicates that photodynamic diagnosis with ALA has a potential in the diagnosis and detection of the sentinel lymph node in patients with breast cancer, and is worth to be further investigated and developed for intraoperative photodynamic diagnosis and possibly therapy.

Administration, Oral↗
PubMed2004

Ciliary motility in bovine oviducts for sensing rapid non-genomic reactions upon exposure to progesterone.

Based on the expression of hormone receptors, oviductal cells receive a series of signals to control the conduit and transport of gametes. Most cells in the inner oviductal mucosa have motile cilia, and the mucociliary system of oviducts represents a prominent object of study for rapid feedback after application of steroid hormones. Using a high-speed reflectometry method, we investigated effects on the ciliary beat frequency (CBF) of bovine oviductal explants after progesterone treatment. To classify changes of CBF as either classic or non-classic reactions, we pretreated primary tissue cultures with mifepristone, an antagonist to the classic progesterone receptor in a second experimental series. In contrast to classical genomic reactions, non-classic or non-genomic reactions are characterized by fast effects, insensitive to the classic receptor antagonist. We observed inhibitory effects on the ciliary beat frequency as soon as 15 minutes after application of progesterone (20 microM), reaching a plateau of about 11 % after 90 minutes. Pretreatment with mifepristone (20 microM) for two hours did not induce significant differences in short-term reactions. However, the inhibitory influence of progesterone after 24 hours could be effectively prevented. Our data confirmed the short-term reaction of CBF as non-genomic or non-classic.

Animals↗
PubMed2002

Photodynamic therapy of DNA mismatch repair-deficient and -proficient tumour cells.

Loss of DNA mismatch repair is a common finding in hereditary nonpolyposis colon cancer as well as in many types of sporadic human tumours. DNA mismatch repair-deficient cells have been reported to be resistant to many chemotherapeutic agents and to radiotherapy, and to have the potential of rapidly acquiring additional mutations leading to tumour progression. Photodynamic therapy is a new treatment modality using light to activate a photosensitiser that preferentially localises in tumour cells. An oxygen dependent photochemical reaction ensues, resulting in selective tumour necrosis. The effect of loss of DNA mismatch repair activity on the sensitivity to photodynamic therapy was tested using pairs of cell lines proficient or deficient in mismatch repair due to loss of either MLH1 or MSH2 protein function. Cells were incubated with the photosensitiser 5,10,15,20-meta-tetra(hydroxyphenyl)chlorin and exposed to laser light at 652 nm with various optical doses ranging from 0-1 J cm(-2). Cell survival was assessed using the clonogenic assay. Loss of MLH1 or MSH2 function was not associated with resistance to photodynamic therapy. MCF-7 cells repeatedly treated with photodynamic therapy expressed parental levels of MLH1, MSH2, MSH6, and PMS2. DNA mismatch repair-deficient and -proficient cells showed similar subcellular distributions of meta-tetra(hydroxyphenyl)chlorin as analysed by laser scanning and fluorescence microscopy. Therefore, repeated exposure of tumour cells to photodynamic therapy does not seem to result in loss of DNA mismatch repair, and loss of mismatch repair, in turn, does not seem to contribute to resistance to photodynamic therapy. Our results suggest recommending photodynamic therapy as a strategy for circumventing resistance due to loss of DNA mismatch repair.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Photodynamic therapy of locoregional breast cancer recurrences using a chlorin-type photosensitizer.

Chest wall recurrences are a frequent problem in patients treated by mastectomy for breast cancer. Surgery and ionizing radiation are established treatment modalities in these cases. Photodynamic therapy (PDT) provides an alternative treatment modality using a photosensitizer and laser light to induce selective tumor necrosis. PDT was performed as compassionate use in 7 patients aged 57.6 years (+/-12.6 SD). A total of 89 metastatic skin nodes were treated in 11 PDT sessions. As photosensitizer meta-tetra(hydroxyphenyl)chlorin (m-THPC) was applied intravenously. Patients (n = 3) photosensitized with a drug dose of 0.10 mg/kg bodyweight were irradiated 48 hr after drug application at a lightdose of 5 J/cm(2). Patients (n = 4) were illuminated by an optical dose of 10 J/cm(2) 96 hr after photosensitization with 0.15 mg/kg. Laser light at a wavelength of 652 nm was generated by a diode laser and applied by a front lens light diffuser using a fluence rate of 20--25 mW/cm(2). PDT using m-THPC resulted in complete response in all patients. Response to treatment did not differ when using the 2 different drugdose protocols. Healing time depended mainly on the size of the illumination field but not on the lightdose. Pain score usually raised 1 day after PDT and lasted at higher levels for about 10 days. Healing time usually ranged between 8--10 weeks. Photodynamic technique offers a minimal-invasive, outpatient treatment modality for recurrent breast cancer on the chest wall with few side effects, high patient's satisfaction and with possible repetitive application.

Antineoplastic Agents↗
PubMed2001

Resistance to topoisomerase poisons due to loss of DNA mismatch repair.

Sporadic breast carcinomas demonstrate microsatellite instability, reflecting the presence of DNA mismatch repair-deficient cells, in about one fourth of cases at the time of diagnosis. Loss of DNA mismatch repair has been reported to result in resistance not only to cisplatin and alkylating agents but also to the topoisomerase II poison doxorubicin, suggesting an association between DNA mismatch repair and topoisomerase II poison-induced cytotoxicity. Our study investigates the relationship between loss of MSH2 or MLH1 function and sensitivity to the topoisomerase I and II poisons, and to the taxanes, 2 classes of cytotoxic drugs commonly used in breast cancer. Two pairs of cell lines proficient and deficient in mismatch repair due to loss of either MSH2 or MLH1 function were used. Loss of either MSH2 or MLH1 function resulted in resistance to the topoisomerase II poisons doxorubicin, epirubicin and mitoxantrone, whereas only loss of MLH1 function was associated with low-level resistance to the topoisomerase I poisons camptothecin and topotecan. In contrast, there was no resistance to docetaxel and paclitaxel. Our data support the hypothesis that both MSH2 and MLH1 are involved in topoisomerase II poison-mediated cytotoxicity, whereas only MLH1 is involved in topoisomerase I poison-mediated cytotoxicity. Since our study shows that loss of DNA mismatch repair does not result in resistance to the taxanes, these drugs can be recommended for use in breast cancer deficient in mismatch repair.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Photodynamic diagnosis of breast tumours after oral application of aminolevulinic acid.

Photodynamic diagnosis is of increasing interest for diagnosis in oncology. It is based on a more intense incorporation of a fluorescent dye in tumours compared to normal tissue. As a feasibility study we investigated the effectiveness of oral application of 5-aminolevulinic acid for photodynamic diagnosis of human primary mammary tumours. The study included 16 patients with palpable breast tumours. Aminolevulinic acid was administered at a concentration of 40 mg kg(-1)bodyweight 150-420 min prior to tumourectomy. Intraoperatively blue light (405 nm) was applied to the operation site. Sections of the excised tumour and some lymph nodes were prepared and analysed with a fluorescent microscope. All primary mammary tumour tissues showed significantly higher fluorescence intensity than surrounding normal mammary tissue. Fluorescence of the mammary tumours could also be discriminated macroscopically and intraoperatively. Fluorescence intensity in nonmetastatic lymph node tissue was higher in 2 out of 3 patients than in primary tumour tissue. By photodynamic diagnosis using aminolevulinic acid we were able to reliably distinguish primary mammary tumours from normal mammary tissue microscopically and macroscopically in all our patients. We suggest that photodynamic diagnosis with aminolevulinic acid for breast tumours should be further investigated and developed for intraoperative use and may well be a simple tool for better intraoperative diagnosis and recognition of tumour margins. We hypothesize that lymph node metastasis of breast tumours will not be detectable by this method.

Administration, Oral↗
PubMed2001

Skin protection for photosensitized patients.

BACKGROUND AND OBJECTIVE: The goal of this study was to evaluate various creams for their capability to protect photosensitized skin from visible light. STUDY DESIGN/MATERIALS AND METHODS: Two cover creams and creams containing various combinations of Vaseline with TiO(2), ZnO, and Fe(2)O(3) were used to measure the reduced light transmission and the light absorption spectrum. In vitro and in vivo tests were performed to assess the protection from light by above mentioned compounds. RESULTS: The cover creams and the 50% TiO(2) cream showed similar efficacy in reducing light transmission, while the sunscreen was less efficient by a factor of 5. Cell protection by 25% TiO(2)+25% ZnO, TiO(2), or the cover creams was more efficient than protection by the sunscreen or other compounds. In vivo, the dark cover cream protected the skin by a factor of 3.4 better than the sunscreen. CONCLUSION: The dark cover cream has acceptable properties to protect photosensitized skin.

Absorption↗
PubMed2001

Primary ciliary dyskinesia with situs inversus totalis, hydrocephalus internus and cardiac malformations in a dog.

A nine-month-old golden retriever bitch was presented with exercise intolerance and recurrent nasal discharge. Based on clinical, radiographic and ultrasonographic examination, a diagnosis of rhinitis, situs inversus totalis and tricuspid valve insufficiency was established. The results of video- and electron microscopy studies of the respiratory epithelium were compatible with primary ciliary dyskinesia (PCD). However, no evidence of a primary ultrastructural defect of the cilia was found. The dog was euthanased because of the poor prognosis. At necropsy, a hydrocephalus internus and a subaortic stenosis were additionally diagnosed. PCD, in combination with situs inversus, has been previously reported in golden retrievers, but without a concomitant hydrocephalus internus. Furthermore, concomitant occurrence of internal cardiac malformation and PCD has not previously been reported in the dog.

Animals↗
PubMed2000

Comparative genomic hybridization of fine needle aspirates from breast carcinomas.

Detailed knowledge of chromosomal aberrations in a specific tumor may facilitate the development of individually tailored chemotherapy, hormone or gene therapy. Unfortunately, karyotype analysis requires living cells and is complicated by the low number of good metaphase spreads obtained. Comparative genomic hybridization (CGH), however, is capable of detecting and mapping genome-wide amplifications and deletions using an equimolar mixture of normal and tumor cell DNA. We show here that even the few cells from a fine needle aspirate of a tumor are sufficient for a direct CGH assay, independent of DNA amplification. Ten primary breast cancers were analyzed by CGH. A fresh frozen fine needle aspirate and a formalin-fixed and paraffin-embedded section were used for each tumor. Metaphases from each CGH reaction were imaged, and a sum ratio profile was determined for every chromosome. The ratio profiles of DNA isolated from the 2 material sources were then compared. Fine needle aspirates and the paraffin-embedded material of a single tumor yielded the same fluorescence ratio profiles, albeit with slightly different confidence intervals. Different tumors showed a variety of aberrations. The most frequently observed changes were 1q+, 8q+, 14q-, 16p+, 16q-, 17p-, 17q+, 19q+, 20q+, 21q- and 22q-. The ability of CGH to assess chromosomal changes in breast cancer from fine needle aspirates could facilitate genetic evaluation of tumors prior to surgery.

Adult↗
PubMed2000

Primary ciliary dyskinesia: a genome-wide linkage analysis reveals extensive locus heterogeneity.

Primary ciliary dyskinesia (PCD), or immotile cilia syndrome (ICS), is an autosomal recessive disorder affecting ciliary movement with an incidence of 1 in 20000-30000. Dysmotility to complete immotility of cilia results in a multisystem disease of variable severity with recurrent respiratory tract infections leading to bronchiectasis and male subfertility. Ultrastructural defects are present in ciliated mucosa and spermatozoa. Situs inversus (SI) is found in about half of the patients (Kartagener syndrome). We have collected samples from 61 European and North American families with PCD. A genome-wide linkage search was performed in 31 multiplex families (169 individuals including 70 affecteds) using 188 evenly spaced (19cM average interval) polymorphic markers. Both parametric (recessive model) and non-parametric (identity by descent allele sharing) linkage analyses were used. No major locus for the majority of the families was identified, although the sample was powerful enough to detect linkage if 40% of the families were linked to one locus. These results strongly suggest extensive locus heterogeneity. Potential genomic regions harbouring PCD loci were localised on chromosomes 3p, 4q, 5p, 7p, 8q, 10p, 11q, 13q, 15q, 16p, 17q and 19q. Linkage analysis using PCD families with a dynein arm deficiency provided 'suggestive' evidence for linkage to chromosomal regions 8q, 16pter, while analyses using only PCD families with situs inversus resulted in 'suggestive' scores for chromosomes 8q, and 19q.

Ciliary Motility Disorders↗
PubMed2000

PEG-m-THPC-mediated photodynamic effects on normal rat tissues.

Photodynamic therapy (PDT) of malignancies uses light to activate a photosensitizer preferentially accumulated in cancer cells. The first pegylated photosensitizer, tetrakis-(m-methoxypolyethylene glycol) derivative of 7,8-dihydro-5,10,15,20-tetrakis(3-hydroxyphenyl)-21-23-[H]-porphyrin (PEG-m-THPC), was evaluated in non-tumor-bearing rats. The aim of this study was to assess the photodynamic threshold for damage and its sequelae in normal rat tissue. Thirty-five Fischer rats were sensitized with 3, 9 or 30 mg/kg body weight PEG-m-THPC. Colon, vagina and perineum were irradiated with laser light of 652 nm wavelength and an optical dose of 50, 150 or 450 J/cm fiber length. Temperature in the pelvis was measured during PDT. Three days following PDT the effect on skin, vagina, colon, striated muscle, connective tissue, nerves and blood vessels was assessed by histology. The healing of the above-mentioned tissues was assessed on two rats 3 and 8 weeks after PDT using 9 mg/kg PEG-m-THPC activated with 450 J/cm laser light. No dark toxicity was observed. PDT using 30 mg/kg PEG-m-THPC induced severe necrosis irrespective of the optical dose. Body weight of 9 or 3 mg/kg activated with less than 450 J/cm induced moderate or no damage. No substantial increase in body temperature was seen during PDT. Tissues with severe PDT-induced damage seem to have a good tendency to regenerate. We conclude that within the dose required for tumor treatment PEG-m-THPC is a safe photosensitizer with promising properties. PDT of the colon mucosa below 9 mg/kg PEG-m-THPC and 150 J/cm seems to be safe. All other tissues can be exposed to 9 mg/kg PEG-m-THPC activated with less than 450 J/cm laser light with little side effects.

Animals↗
PubMed1999

Bispecific antibody-mediated lysis of primary cultures of ovarian carcinoma cells using multiple target antigens.

We have shown previously that a bispecific antibody (BsAb) directed against both germ-cell alkaline phosphatase (GCAP) and the CD3 complex on mouse T cells could effectively eliminate GCAP-positive tumor cells in vivo using an immunocompetent mouse model. However, some GCAP-negative tumor cells were still able to grow, suggesting that BsAb therapy, when used in a clinical setting, could benefit from targeting several tumor markers to prevent outgrowth of tumor cells lacking a targeted marker. To test this hypothesis, we developed an in vitro model based on primary human ovarian carcinoma (OC) cultures and BsAbs directed against human T cells and several tumor markers [placental alkaline phosphatase (PLAP), GCAP, folate-binding protein (FBP) and CA19.9]. OC cells, isolated from primary tumors, were co-cultured with human peripheral blood mononuclear cells in the presence or absence of various concentrations of BsAbs against PLAP/GCAP, FBP and CA19.9 administered separately or in combination. Results derived from 18 primary OC samples showed that the combination treatment was better than or equally effective as the best single BsAB treatment in 60% of cases. Sometimes targeting FBP, PLAP/GCAP or CA19.9 alone was superior to targeting all simultaneously. Combining each BsAb with a low dose of IL-2 was always beneficial. These results indicate that before using a specific BsAb in the clinic, it is important to determine the optimal BsAb for each patient using this in vitro assay on cells from the removed tumor mass.

Animals↗
PubMed1999

Photodynamic therapy for the hypercalcemic type of the small cell carcinoma of the ovary in a mouse xenograft model.

OBJECTIVE: The hypercalcemic type of the small cell carcinoma of the ovary (HTSCCO) is a rapidly fatal ovarian tumor in young women. Photodynamic therapy (PDT) induces selective necrosis to malignant tissues. The aim of this study was to determine the sensitivity of the HTSCCO to PDT in a mouse xenograft model. METHODS: Tumors were obtained from a patient with a HTSCCO and were transplanted into nude mice. Following photosensitization with m-THPC, either superficial or interstitial laser light was administered to the tumors. Necroses were measured by morphometry. Serum calcium levels were determined prior to and after PDT. RESULTS: Superficial irradiation of m-THPC sensitized tumors showed over three times more necrosis than control tumors (P = 0.037). Interstitially irradiated tumors showed over seven times more necrosis than control tumors (P = 0.0012). All animals showed a highly significant hypercalcemia prior to PDT (P < 0.0001). PDT induced a significant decrease in serum calcium levels (P = 0.0297). CONCLUSION: This study suggests that PDT may be of therapeutic value for the HTSCCO.

Animals↗
PubMed1999

Photodynamic effects in vitro in fresh gynecologic tumors analyzed with a bioluminescence method.

Photodynamic therapy (PDT) is a promising alternative method for clinical cancer treatment. In the present study, cells from four breast carcinomas, seven ovarian carcinomas of various stages of differentiation, and ascites from a diffuse metastatic tumor were treated by PDT in vitro. Tetra(m-hydroxyphenyl)-chlorin (m-THPC) was used as the photosensitizer. Surviving cell rate was evaluated by the ATP-Cell-Viability-Assay (ATP-CVA), which measures light production as an interaction of intracellular ATP with the luciferin-luciferase complex. The most effective PDT of the tumor cells was achieved at an m-THPC concentration of 0.2 microgram/ml following incubation of the cells with photosensitizer for 24 hours. PDT toxicity resulted in a cell survival rate of 1% to 42% compared to untreated control cells (survival rate of control = 100%). The inhibitor concentration IC50 of m-THPC was determined both in the dark (dark toxicity) and in combination with laser irradiation. IC50 was defined as the concentration of photosensitizer which caused 50% of cell death. The IC50 values were heterogeneous in all tumor specimens examined. IC50 values for dark toxicity were on average 0.14 microgram m-THPC/ml for primary ovarian carcinoma, 2.16 micrograms m-THPC ml for refractory ovarian carcinoma and 0.3 microgram m-THPC/ml for breast carcinoma. After PDT, average IC50 value for refractory ovarian carcinoma was 0.04 microgram m-THPC/ml, for primary ovarian carcinoma 0.05 microgram m-THPC/ml and for breast carcinoma 0.03 microgram m-THPC/ml. These data might indicate that clinical PDT of gynecological carcinoma requires individual treatment conditions to achieve optimal results.

Breast Neoplasms↗
PubMed1998

[Photomedicine in gynecology].

In ancient years, knowledge about healing capacity of extracts from plants together with sunshine became evident in medicine. In our days second generation photosensitizers (they stand for plant extracts) and laser light (stands for sunshine) are ready for use in the clinic. Photomedicine recently became a selfstanding clinical area composed of photodynamic diagnosis (PDD) and photodynamic therapy (PDT) as its subdisciplines. Clinical application of photomedicine in gynaecology has been carefully prepared. By a number of experiments using in vitro and in vivo techniques a basis was developed to make possible clinical photomedical applications in gynaecology. In PDD 5-aminolevulinic acid, a stimulator for the production of cellular protoporphyrin IX, was used for the detection of tumour lesions of microscopical dimensions. Another approach in PDD called Frequency Domain Photon Migration technology makes it possible to quantify amounts of hem, water and oxygen in a given (tumour) tissue area. They are different from normal breast tissue. In PDT besides new technological components (diode lasers, light diffusers) there is specific need for new photosensitizers whose wavelength of activation is in the area of near infrared, allowing a better tissue penetration. Very recently, research results indicated that PDT does not create resistance against its own and suggest that this procedure can be used successfully even after radio- and/or chemotherapy. PDT of non-neoplastic but pathological cell proliferation such as endometriosis is very promising. One goal in gynaecology will be a reduction of the number of hysterectomies surgically performed by this minimally invasive approach.

Aminolevulinic Acid↗