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R Weber

Publications and source records attributed to R Weber.

At least 91 records · Page 5Linked to original sources
PubMed2000

Detection of hypoxia in human squamous cell carcinoma by EF5 binding.

Localization and quantitation of 2-nitroimidazole drug binding in low pO2 tumors is a technique that can allow the assessment of hypoxia as a predictive assay. EF5 [2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl) acetamide] is such a drug, and it has been shown to be predictive of radiation response in rodent tumors. Using fluorescence immunohistochemical techniques, we provide data on the presence, distribution, and levels of EF5 binding as a surrogate for hypoxia in human head and neck and uterine cervix squamous cell cancers (SCCs). Six patients with SCC were studied. Four patients had head and neck tumors, and two had uterine cervix cancers. The incubation of fresh tissue cubes in EF3 under hypoxic conditions ("reference binding") demonstrated that all tumors were capable of binding drug, and that this binding varied by a factor of 2.9-fold (174.5-516.1) on an absolute fluorescence scale. In the five patients treated at the lowest drug doses (9 mg/kg), in situ binding was quantitatable. For all six patients, the maximum rate of in situ binding varied by a factor of 6.7 between the lowest and highest binding tumor (24.8-160.3) on an absolute fluorescence scale. In tumors with high binding regions, intratumoral heterogeneity was large, extending from minimal fluorescence (<1%) up to 88.6% of reference binding. In tumors with minimal binding, there was little intratumoral heterogeneity. These studies demonstrate substantial heterogeneity of in situ binding between and within individual squamous cell tumors.

Adult↗
PubMed2000

The role of clinical suspicion in evaluating a new diagnostic test for active tuberculosis: results of a multicenter prospective trial.

CONTEXT: In laboratory trials, nucleic acid amplification tests for the diagnosis of tuberculosis (TB) are more accurate than acid-fast bacilli (AFB) smear microscopy and are faster than culture. The impact of these tests on clinical diagnosis is not known. OBJECTIVE: To assess the performance of a nucleic acid amplification test, the enhanced Mycobacterium tuberculosis Direct (E-MTD) test, against a uniform clinical standard stratified by level of clinical suspicion. DESIGN: Prospective multicenter trial conducted between February and December 1996, documenting the clinical suspicion of TB at enrollment and using final comprehensive diagnosis as the criterion standard. SETTING: Six urban medical centers and 1 public health TB clinic. PATIENTS: A total of 338 patients with symptoms and signs consistent with active pulmonary TB and complete clinical diagnosis were stratified by the clinical investigators to be at low (< or =25%), intermediate (26%-75%), or high (>75%) relative risk of having TB. MAIN OUTCOME MEASURES: Sensitivity, specificity, and positive and negative predictive values of the E-MTD test in clinical suspicion of groups with low (n = 224); intermediate (n = 68); and high (n = 46) clinical suspicion of TB. RESULTS: Based on comprehensive clinical diagnosis, sensitivity of the E-MTD test was 83%, 75%, and 87% for low, intermediate, and high clinical suspicion of TB, respectively, and corresponding specificity was 97%, 100%, and 100% (P = .25). Positive predictive value of the E-MTD test was 59% (low), 100% (intermediate), and 100% (high) compared with 36% (low), 30% (intermediate), and 94% (high) for AFB smear. Corresponding negative predictive values were 99%, 91%, and 55% [corrected] (E-MTD test) vs 96%, 71%, and 37% (AFB smear). CONCLUSIONS: For complex diagnostic problems like TB, clinical risk assessments can provide important information regarding predictive values more likely to be experienced in clinical practice. For this series, a clinical suspicion of TB was helpful in targeting areas of the clinical spectrum in which nucleic acid amplification tests can make an important contribution.

Adult↗
PubMed2000

Effects of early antiretroviral treatment on HIV-1 RNA in blood and lymphoid tissue: a randomized trial of double versus triple therapy. Swiss HIV Cohort Study.

To assess the effects of early initiation of antiretroviral therapy on cell-free and cell-associated viral load in blood and lymphoid tissue, we performed a randomized, open-label, multicenter trial comparing a double (zidovudine + lamivudine) and triple (zidovudine + lamivudine + ritonavir) drug combination in treatment-naive, asymptomatic patients with CD4 counts >400 cells/microl. HIV-1 RNA was measured in plasma, peripheral blood mononuclear cells, and sequential tonsil or lymph node biopsies (27 patients); the study follow-up was 2 years. Among 42 randomized patients, the proportion with plasma HIV-1 RNA <50 copies/ml was 16% and 74% at week 24 (p<.001) in those randomized to double and triple therapy, respectively, necessitating frequent treatment intensification in the double arm. After a rapid decline within 4 weeks in both arms, cell-associated HIV-1 RNA decreased further only in those patients with sustained suppression of plasma viral load, but remained almost always detectable at low levels, indicating persisting transcription of viral RNA. CD4 counts increased by 200 to 250 cells/microl at week 96 in both arms without significant differences (intent-to-treat analyses). Thus, even if treatment is initiated early in asymptomatic patients with preserved CD4 counts, three drugs are necessary to achieve sustained decreases of HIV load in blood and lymphoid tissue.

Adult↗
PubMed2000

[What is the value of the Denecke surgical therapy concept in deglutition disorders?].

BACKGROUND: Denecke developed 1957 a surgical strategy consisting of three or four operative steps for rehabilitation of patients with unilateral paralysis of IXth and Xth cranial nerve. These four steps are the following: myotomy of the cricopharyngeal muscle, resection of the paralyzed pharyngeal wall, medialization of the paralyzed vocal cord and fixation of the soft palate to the posterior pharyngeal wall which can be facultative. PATIENTS AND METHODS: For the first time we have reviewed patients operated on with the Denecke operation in a retrospective study. The surgical results should be analyzed to deduce some parameters for surgical indication. RESULTS: 16 patients were reviewed in regard to nourishment status, situation of tracheostomy, former pneumonias, classification of Miller and Eliachar for aspiration and subjective evaluation. The follow-up was 21 +/- 16 months postoperatively. In 8 cases surgical intervention was successful. In 2 additional cases the results were partially satisfying. CONCLUSIONS: The surgical procedure of Denecke was successful for improving substantially nourishment and aspiration status of considerably reduced patients in about 50% of the reviewed cases. Preoperative cinematography of swallowing, manometry and an interdisciplinary approach are required to clearly define the indications for surgical intervention.

Adult↗
PubMed2000

Matrix metalloproteinase 9 promoter activity is induced coincident with invasion during tumor progression.

Matrix metalloproteinase 9 (MMP-9, also known as gelatinase B or 92-kd Type IV collagenase) is overexpressed in many human and murine cancers. We induced carcinomas in mice carrying a transgene that links the MMP-9 promoter to the reporter ss-galactosidase so that activation of the MMP-9 promoter would be indicated by ss-galactosidase. Mammary carcinomas were induced by mating the MMP-9 promoter reporter transgenic mice with mice carrying a transgene for murine mammary tumor virus promoter linked to polyoma middle T antigen, a transgene that leads to rapid development of mammary tumors in female mice. None of the hyperplastic mammary glands and none of the carcinomas in situ expressed ss-galactosidase. However, all invasive tumors had evidence of ss-galactosidase expression. In addition to the breast carcinomas, a malignant teratoma in a female and a papillary adenocarcinoma in the pelvic region of a male arose and were also ss-galactosidase positive. We also induced skin tumors in the mice with the MMP-9 reporter transgene with 7, 12-dimethylbenz[a]anthracene (DMBA) treatment followed by phorbol 12 myristate 13-acetate (TPA). None of the papillomas or in situ carcinomas showed any ss-galactosidase expression, but expression was seen in invasive carcinoma. Although normal skin epithelial cells did not express ss-galactosidase, we did find staining in a few cells at the duct of the sebaceous gland at the base of the hair follicles. The MMP-9 reporter transgene did not lead to expression in the alveolar macrophages, confirming that additional upstream sequences are required for expression in macrophages. These experiments have revealed that MMP-9 promoter activity is induced coincident with invasion during tumor progression. Furthermore, this indicates that the more proximal upstream elements of the promoter are sufficient for MMP-9 transcription during tumor progression.

Animals↗
PubMed2000

Treatment-induced decline of human immunodeficiency virus-1 p24 and HIV-1 RNA in lymphoid tissue of patients with early human immunodeficiency virus-1 infection.

We report detailed quantitative analysis of human immunodeficiency virus-1 (HIV-1) p24 and HIV-1 RNA in tonsil biopsies from 13 patients with early, asymptomatic HIV infection before and during combination antiretroviral therapy. Using fluorescent microscopy in conjunction with reverse transcriptase-polymerase chain reaction of frozen tissue sections, we show that plasma and tissue viral loads decreased by approximately 3 logs during the 1-year treatment period, with good correlation between the HIV-1 p24 and HIV-1 RNA response in tissue. The decrease of tissue viral load was delayed compared to plasma viral load, possibly explained by the observation that the amount of follicular dendritic cell-associated virus correlated best with the area under the curve of plasma HIV-1 RNA throughout the last 12 weeks. Before and during treatment, the relative proportions of HIV-1 on follicular dendritic cells and within mononuclear cells remained constant, suggesting similar decay characteristics in these two lymphoid tissue compartments. However, viral p24 or RNA remained almost always detectable in tissue despite full suppression of HIV-1 RNA in plasma, and increased even after short-term rebounds in plasma viral load. Thus, full and sustained suppression of viral replication was required to efficiently decrease viral load in lymphoid tissue, but complete abolition of residual viral replication was not achieved.

Anti-HIV Agents↗
PubMed2000

[Endonasal endoscopic surgery of maxillary sinus mucoceles after Caldwell-Luc operation].

BACKGROUND: Mucoceles of the maxillary sinus after Caldwell-Luc procedure develop by entrapment of mucosa. Specially mucoceles far laterally were being revised by a second transoral approach. This procedure carries the risk of damaging the infraorbital nerve. In addition the problem of scarring at the bottle neck between the lateral recessus and the nasal cavity with reclosure remains. METHODS AND PATIENTS: In 3 patients with a mucocele of the maxillary sinus 4-25 years after Caldwell-Luc operation an endonasal endoscopic opening of the mucocele was performed. In addition a silicon spacer was placed for 6 months. RESULTS: Twelve to fifteen months postoperatively all 3 patients still had an uneventful maxillary sinus according to the data of endoscopy, computer-tomographic or MRI-examination. CONCLUSIONS: The endoscopic approach and the long standing placement of a splint seems to be a valuable alternative to a renewed somewhat risky Caldwell-Luc approach.

Adult↗
PubMed2000

Osteoplastic frontal sinus surgery with fat obliteration: technique and long-term results using magnetic resonance imaging in 82 operations.

OBJECTIVE: To evaluate the intraoperative and late complications of osteoplastic sinus surgery with fat obliteration with long-term magnetic resonance imaging (MRI) follow-up. METHODS: The operative records of all patients who underwent osteoplastic frontal sinus surgery with fat obliteration between January 1, 1986 and December 31, 1997 were reviewed and the postoperative clinical course and magnetic resonance imaging (MRI) scans were analyzed if available. MRI analyses revealed that changes in the distribution of fatty and fibrous tissue, the development of necrosis or oil cysts, recurrences, inflammatory complications, and mucoceles were time-dependent occurrences. RESULTS: Eighty-two operative records were evaluated and 59 patients were followed 1 to 12 years after surgery. Eighty-six MRI scans in 51 patients were available for analysis. The most frequent intraoperative complications were exposure of orbital fat (19.5%), unintentional fracture of the anterior wall (19.5%), incorrect placement of the anterior wall (17%), and dural injury (9.8%). Persistent changes of the frontal contour (embossment, depression) occurred in 10.2% and the esthetic result was unfavorable in 5.1% of the cases. Mucoceles could be detected in 5 of 51 cases (9.8%). The amount of adipose tissue detectable in the last scan was less than 20% in the majority of cases (53%), and more than 60% in only 18% of the cases. The amount of adipose tissue decreased significantly with time (the median half-life was 15.4 mo). CONCLUSIONS: Osteoplastic frontal sinus surgery with fat obliteration is very useful and successful in patients in whom the frontal sinus is not accessible via an endonasal approach or the natural drainage cannot be reestablished. MRI is currently the most valuable diagnostic tool to evaluate the frontal sinus after obliteration with adipose tissue. The method has some limitations with regard to detection of small recurrent mucoceles and differentiating vital adipose tissue from fat necroses in the form of oil cysts. In these difficult cases, long-term MRI follow-up is necessary.

Adipose Tissue↗
PubMed2000

Phagocytic uptake of Encephalitozoon cuniculi by nonprofessional phagocytes.

Encephalitozoon cuniculi is an obligate intracellular, spore-forming parasite belonging to the microsporidia that can cause disseminated infection in immunocompromised persons. E. cuniculi spores infect host cells by germination, i.e., by explosively everting the polar filament, through which the spore contents (sporoplasms) are subsequently injected into the cytoplasm. In addition, we observed intracellular, nongerminated spores in various nonprofessional phagocytes. In MRC5 cells, the number of internalized spores was approximately 10-fold higher than the number of injected sporoplasms. Compared to the rate of uptake by human monocyte-derived macrophages, internalization rates by A549 cells, MRC5 cells, and 293 cells were 0.6, 4.4, and 22.2%, respectively. The mechanism of uptake was studied in MRC5 cells. Killed spores were internalized at the same rate as live spores, indicating that nongerminated parasites do not actively participate in cell entry. Cytochalasin D inhibited uptake of spores by 95%, demonstrating an actin-dependent process. By electron and epifluorescence microscopy, intracellular spores were found in a tightly fitting membrane-bound compartment. The vacuole containing the spores was positive for the lysosomal membrane protein LAMP-1 and colocalized with the late endosomal-lysosomal content marker rhodamine dextran. Our results show that, in addition to the unique way in which microsporidia infect cells, E. cuniculi spores enter nonprofessional phagocytes by phagocytosis and traffic into a late endosomal-lysosomal compartment.

Actins↗
PubMed2000

Molecular characterization of Cryptosporidium isolates obtained from human immunodeficiency virus-infected individuals living in Switzerland, Kenya, and the United States.

A total of 22 Cryptosporidium isolates from human immunodeficiency virus-infected patients from Kenya, Switzerland, and the United States were examined at three genetic loci: the 18S ribosomal DNA, HSP-70, and acetyl coenzyme A synthetase genes. Four distinct Cryptosporidium genotypes were identified: (i) the Cryptosporidium parvum "human" genotype, (ii) the C. parvum "cattle" genotype, (iii) Cryptosporidium felis, and (iv) Cryptosporidium meleagridis. This is the first report of C. meleagridis in a human host. These results and those of others indicate that immunocompromised individuals are susceptible to a wide range of Cryptosporidium species and genotypes. Future studies are required to understand the full public health significance of Cryptosporidium genotypes and species in immunocompromised hosts.

AIDS-Related Opportunistic Infections↗
PubMed2000

Mutations in the tropoelastin gene (ELN) were not found in patients with spontaneous cervical artery dissections.

BACKGROUND AND PURPOSE: The majority of patients with spontaneous cerebral artery dissection show ultrastructural alterations in dermal collagen and elastic fibers. METHODS: We studied the gene encoding tropoelastin (ELN) by reverse transcription-polymerase chain reaction and subsequent sequence analysis in 10 patients with abnormalities in their elastic fibers. RESULTS: No mutations were found in the whole coding region of the ELN gene. The simultaneous visualization and quantification of ELN splice variants by gene scanning enabled the analysis of the regulation of alternative splicing of ELN mRNA. No differences could be detected between fibroblast cultures of the patients and a control subject. CONCLUSIONS: Neither mutations in the ELN gene nor dysregulation of its activity appears to be the cause of the connective tissue disorder that is found in most patients with spontaneous dissections.

Adult↗
PubMed2000

PCR-derived ssDNA probes for fluorescent in situ hybridization to HIV-1 RNA.

We developed a simple and rapid technique to synthesize single-stranded DNA (ssDNA) probes for fluorescent in situ hybridization (ISH) to human immunodeficiency virus 1 (HIV-1) RNA. The target HIV-1 regions were amplified by the polymerase chain reaction (PCR) and were simultaneously labeled with dUTP. This product served as template for an optimized asymmetric PCR (one-primer PCR) that incorporated digoxigenin (dig)-labeled dUTP. The input DNA was subsequently digested by uracil DNA glycosylase, leaving intact, single-stranded, digoxigenin-labeled DNA probe. A cocktail of ssDNA probes representing 55% of the HIV-1 genome was hybridized to HIV-1-infected 8E5 T-cells and uninfected H9 T-cells. For comparison, parallel hybridizations were done with a plasmid-derived RNA probe mix covering 85% of the genome and a PCR-derived RNA probe mix covering 63% of the genome. All three probe types produced bright signals, but the best signal-to-noise ratios and the highest sensitivities were obtained with the ssDNA probe. In addition, the ssDNA probe syntheses generated large amounts of probe (0.5 to 1 microg ssDNA probe per synthesis) and were easier to perform than the RNA probe syntheses. These results suggest that ssDNA probes may be preferable to RNA probes for fluorescent ISH. (J Histochem Cytochem 48:285-293, 2000)

Cell Line↗
PubMed2000

Mesenchymal cells engulf and clear apoptotic footplate cells in macrophageless PU.1 null mouse embryos.

Apoptosis is one of the key tools used by an embryo to regulate cell numbers and sculpt body shape. Although massive numbers of cells die during development, they are so rapidly phagocytosed that very few corpses are ever seen in most embryonic tissues. In this paper, we focus on the catastrophic cell death that occurs as the developing footplate is remodelled to transform webbed regions into free interdigital spaces. In the wild-type embryo, these dead cells are rapidly engulfed and cleared by macrophages. We show that in a macrophageless mouse embryo, null for the haemopoetic-lineage-specific transcription factor, PU.1, the task of phagocytosis is taken over by 'stand-in' mesenchymal neighbours in a clear example of cell redundancy. However, it takes three times as many of these mesenchymal phagocytes to complete the task and, at each stage of the clearance process - in the recognition of apoptotic debris, its engulfment and finally its digestion - they appear to be less efficient than macrophages. A molecular explanation for this may be that several of the engulfment genes expressed by macrophages, including the ABC1 transporter (believed to be part of the phagocytic machinery conserved from Caenorhabditis elegans to mouse), are not upregulated by these 'stand-in' phagocytes.

Animals↗