Fine structure of human immunodeficiency virus (HIV) and immunolocalization of structural proteins

Ultrathin section and surface replica electron microscopy were applied in combination with immunoelectron microscopy to elucidate the fine structure of HIV. The shell of the tubular core shows p24 antigenicity, while p17 is located at the inner leaflet of the lipid membrane. The virus particle is studded with 70-80 protrusions. These knobs have a diameter of 15 nm, a height of 9 nm, and are probably arranged in a T = 7 I symmetry. The major envelope protein gp120 is spontaneously shed from the viral surface. A possible role of released gp120 in pathogenesis is discussed.     

Vitamin D-Stoffwechsel und Niereninsuffizienz

Zusammenfassung Es wurden Untersuchungen über den Langzeitmetabolismus von Vitamin D bei Normalpersonen und Patienten mit Niereninsuffizienz durchgeführt. Nach intravenöser Injektion von Vitamin D₃-H₃ zeigte sich in den untersuchten Serumproben weder für die Halbwertszeit noch für die Verteilung von Vitamin D und seinen verschiedenen Metaboliten ein Unterschied zwischen den beiden Gruppen. Diese Untersuchungsergebnisse machen es sehr unwahrscheinlich, daß eine Vitamin D-Stoffwechselstörung für die Entwicklung der azotämischen Osteopathie verantwortlich ist.

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Summary Investigations have been performed in normal subjects and renal patients on the long term metabolism of vitamin D₃. After an intravenous injection of tritiated vitamin D₃ there was no difference between both groups: halflife and the distribution of vitamin D and its various metabolites in the serum were almost identical. Our results suggest that a disorder of vitamin D metabolism is not responsible for the development of the azotemic osteodystrophy.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Intravenous permanent catheterization in cats

Summary A surgical procedure is described for the insertion of i.v. catheters in cats. The animals operated in this way can move around freely in their cages.     

Ring chromosome 22 and neurofibromatosis

Variable constitutional mosaicism, mos45,XY,-22/46,XY,-22,+mar/46,XY,-22,+r(22)/47,XY,-22,+r(22)+mar/ 47, XY,-22,+r(22)*2, was found in PHA-stimulated peripheral blood, in a lymphoblastoid cell line and in cultured skin fibroblasts from a mentally retarded patient with neurofibromatosis. Both the ring chromosome and the small extra marker chromosome stained positively by in situ hybridization with a chromosome 14/22-specific alphoid repeat probe. DNA dosage analysis showed constitutional loss of one copy of the arylsulfatase A gene (ARSA), consistent with its terminal location on 22q. There was no evidence of constitutional loss of D22S1 or D22S28 which flank the neurofibromatosis type 2 (NF2) locus. Analysis of two DNA samples from a skin neurofibroma indicated retainment of two copies of D22S1, whereas the results were ambiguous with respect to tumor-specific loss of one copy of D22S28. It is suggested that the development of neurofibromatosis of unclear type in two r(22) carriers might be associated with somatic mutation of the NF2 locus due to instability of the ring chromosome(s), and in analogy, that somatic mutation of either NF1 or NF2 may account for some cases of neurofibromatosis which do not meet the criteria of either NF1 or NF2. The occurrence of seminoma in the proband may be fortuitous, but could also be due to the presence of a seminoma-associated locus on chromosome 22.     

Modification of collagen matrices for enhancing angiogenesis

The vascularization of engineered tissues in many cases does not keep up with the ingrowth of cells. Nutrient and oxygen supply are not sufficient, which ultimately leads to the death of the invading cells. The enhancement of the angiogenic capabilities of engineered tissues therefore represents a major challenge in the field of tissue engineering. The immobilization of angiogenic growth factors may be useful for enhancing angiogenesis. The most potent angiogenic growth factor specific to endothelial cells, vascular endothelial growth factor (VEGF), occurs in several splice variants. The variant with 165 amino acids both has a high angiogenic activity and a high affinity for heparin. We therefore incorporated heparin molecules into collagen matrices by covalently cross-linking them to amino functions on the collagen. Physical binding of VEGF to the heparin may then prevent a rapid clearance from the implant, while the release rate may become coupled to the degradation of the collagen matrix. The modified matrices were characterized by determination of the extent of the heparin immobilization, the in vitro degradation rate by collagenase. For testing the angiogenic properties, non-modified and heparinized collagen specimens were--either loaded with VEGF or non-loaded--subcutaneously implanted on the back of rats. Specimens were explanted after varying periods of implantation, the dry weights and the hemoglobin contents, as well as immunostained histological sections were evaluated: heparinized collagen matrices loaded with VEGF are vascularized to a substantially higher extent as compared to non-modified matrices.     

Bacterial wall as target for attack: past, present, and future research

When Bacteria, Archaea, and Eucarya separated from each other, a great deal of evolution had taken place. Only then did extensive diversity arise. The bacteria split off with the new property that they had a sacculus that protected them from their own turgor pressure. The saccular wall of murein (or peptidoglycan) was an effective solution to the osmotic pressure problem, but it then was a target for other life-forms, which created lysoymes and beta-lactams. The beta-lactams, with their four-member strained rings, are effective agents in nature and became the first antibiotic in human medicine. But that is by no means the end of the story. Over evolutionary time, bacteria challenged by beta-lactams evolved countermeasures such as beta-lactamases, and the producing organisms evolved variant beta-lactams. The biology of both classes became evident as the pharmaceutical industry isolated, modified, and produced new chemotherapeutic agents and as the properties of beta-lactams and beta-lactamases were examined by molecular techniques. This review attempts to fit the wall biology of current microbes and their clinical context into the way organisms developed on this planet as well as the changes arising since the work done by Fleming. It also outlines the scientific advances in our understanding of this broad area of biology.     

Systematic assessment of atypical deletions reveals genotype-phenotype correlation in 22q11.2

Introduction: Clinical variability associated with the common 22q11.2 microdeletion is well known, and has led to a broad application of FISH diagnostics with probes for loci TUPLE1 or D22S75 (N25), although, rarely reported atypical deletions associated with the same phenotypic spectrum would not be discovered by these probes. As most types of 22q11.2 deletions occur between low copy repeats within the region (LCR22), we assumed that atypical deletions should be more common than has been reported. To address this question and the possibility of a deletion size related genotype-phenotype correlation, we systematically assessed the frequency of typical and atypical 22q11.2 deletions in a large cohort of patients. Methods: We used a set of 10 fluorescent in situ hybridisation (FISH) DNA probes, capable of detecting all reported and hypothetical deletions between the LCR22, and analysed 350 patients. Deletion sizes in atypical deletions were established by use of further FISH probes. Frequency of certain atypical deletions was analysed in controls by FISH and quantitative PCR. Results: Patients with conotruncal heart defects (ctCHD) and with typical VCFS phenotype showed the common 3 Mb or nested 1.5 Mb deletions (in 18.5% and 78.6%, respectively), but no atypical deletion, while 5% (3/63) of patients with a mildly suggestive, atypical phenotype showed atypical distal deletions, which were not detected in patients with mental retardation of unknown origin or in healthy controls. Discussion: These statistically significant differences demonstrate that atypical distal 22q11.2 deletions are very uncommon in patients with ctCHDs, while atypical congenital heart defects and mild dysmorphism are recognisable feature of atypical distal deletions. Further phenotype-genotype analysis disclosed association of significant developmental delay with the distal part of the common deletion region, and choanal atresia and atypical CHDs with the adjacent distal deletion region.     

Diagnosis of allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis

BACKGROUND: The diagnosis of allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) patients may be difficult to establish because ABPA shares many characteristics with coexisting atopy or other lung infections in these patients. This study aimed to evaluate the sensitivity and specificity of various paraclinical parameters in the diagnosis of ABPA in patients with CF. METHODS: Accumulated data from a 5-year period in 238 CF patients were used to divide patients into two groups designated the ABPA group (n=26) and the non-ABPA group (n = 35). Patients in both groups were colonized with Aspergillus fumigatus (Af.), but only the ABPA group consistently demonstrated specific IgE antibodies and specific precipitins. Patients without A. fumigatus colonization were not assigned to either of these groups (n = 177). By this selection as the true diagnosis, 10 patients were selected from the ABPA group and 10 patients from the non-ABPA group. RESULTS: The groups were comparable as to age, sex, lung function (P=0.6), and presence of chronic Pseudomonas aeruginosa infection (P>0.1). No significant difference between the groups in unspecific atopic parameters such as eosinophil count (P=0.9) or eosinophil cationic protein (ECP) in sputum, plasma, or serum (P=0.9, P=0.59, and P = 0.9, respectively) was demonstrated. Total IgE was significantly higher in the ABPA group (P<0.01). The groups were comparable in skin prick test (SPT) positivity to a standard panel of aeroallergens (pollen, dander, molds, and mites) (P>0.2). Statistically significantly higher levels in the ABPA group were demonstrated in specific IgE to Af. (P < 0.05), SPT positivity to Af. (P < 0.02), and Af. precipitins (P < 0.05). Histamine release (HR) to Af. tended to be higher (P=0.075) in the ABPA group. Specific IgE to Af. was determined by Magic Lite (ML), CAP, and Maxisorp (in-house RAST). The CAP level was one to two classes higher than the ML level; however, the results were comparable (r=0.66, P<0.005). IgE to Af. measured by CAP was the test which offered the highest positive predictive value (PPV) and negative predictive value (NPV). Optimal diagnostic cutoff levels for the diagnosis of ABPA were determined: class 2 for HR to Af., 200 kIU/l for total IgE, and 3.5 (titer) for precipitating antibodies to Af., and class 2 for IgE to Af. (by CAP System). CONCLUSIONS: Unspecific atopy markers were of limited value for the diagnosis of ABPA. Patients with ABPA do not seem to be more atopic to other aeroallergens than non-ABPA patients. The most valid parameters for the diagnosis of ABPA in CF are SPT to Af., IgE to Af. in combination with precipitating antibodies to Af., and/or total IgE.     

Spontaneous suppressor cell activity in the peripheral blood of patients with malignant and chronic inflammatory bowel diseases.

Fifteen patients with colorectal tumours, 15 patients with Crohn's disease (CD) and two groups of normal controls were investigated for the presence of spontaneous suppressor cell activity (SSCA) in peripheral blood mononuclear cells (PBMC). In comparison to the age and sex matched controls patients with colorectal carcinoma exhibited a significant increase in SSCA (P less than 0.01). No evidence could be obtained that the suppressive effect was due to a soluble factor such as prostaglandins. In contrast, patients suffering from CD presented a decreased SSCA. No correlation was obtained between the enhanced SSCA in tumour patients and the clinical stage of the disease, levels of oncofetal antigens or serum immune complexes. Likewise in patients with CD no correlation was found between decreased SSCA and CD index or different serum parameters. When PBMC of the different test groups were incubated with histamine or cimetidine before they were added to the indicator system the suppressive activity remained unchanged. Also pre-incubation of normal PBMC with alpha-fetoprotein or carcinoembryonic antigen did not change the spontaneous suppressor cell activity. Whether the significantly enhanced in vivo activity of spontaneous suppressor cells in patients with colorectal carcinoma is one of the multifactorial mechanisms leading to the establishment of cancer or whether it rather represents a reflection of the immune system on colorectal tumour antigens remains unsolved.     

Die Rolle des Erythropoietinmangels in der Pathogenese der renalen Anämie

Zusammenfassung Es wird eine Übersicht gegeben über klinische Untersuchungen, die mit einem hochsensiblen in-vitro Erythropoietin Assay (foetale Mäuseleberzellkultur) zur Klärung der umstrittenen Rolle des Erythropoietinmangels in der Pathogenese der renalen Anämie an großen Patientenpopulationen durchgeführt wurden. Die Studien betrafen: a.) chronisch Nierenkranke mit variierender Funktionsein-schränkung in der Vordialysephase b.) nicht nephrektomierte und anephrische chronische Dialysepatienten.Die bisher vorliegenden Ergebnisse belegen, daß die Anfangsphase der renalen Anämie mit einem kompensatorischen Anstieg der Serumerythropoietinkonzentration einhergeht und somit ein Erythropoietinmangel nicht die primäre Ursache dieser Anämie sein kann; lediglich ein relativer Erythropoietinmangel ist anzunehmen. Erst in der Terminalphase der Niereninsuffizienz wird der Erythropoietinmangel absolut, so bei 50% der untersuchten chronischen, nichtnephrektomierten Hämodialysepatienten und bei allen anephrischen Patienten. An einzelnen Patienten läßt sich aber selbst in der terminalen Niereninsuffizienz eine Regulierbarkeit der Serumerythropoietinkonzentration über den Hämatokrit im Sinne eines negativen feedback nachweisen, der auf einem subnormalen Hämatokritniveau arbeitet.