ATP hydrolysis by ischemic mitochondria

Cellular ATP levels are determined by the rates of ATP production and ATP hydrolysis. Both phenomena are affected by ischemia. Mitochondrial enzymes are damaged, inhibiting this organelle's ability to make ATP. Mitochondria are also uncoupled by ischemia and have the ability to hydrolyze ATP. We designed a series of experiments to determine whether decreased production or increased hydrolysis of ATP was the primary effect of mitochondrial damage. Rat hearts were subjected to 45 min of warm ischemia in order to induce irreversible cell damage. ATP or ADP was injected into cuvettes containing mitochondria isolated from normal myocardium or myocardium damaged by ischemia. Luciferin-luciferase, which fluoresces in the presence of ATP, was also added to the tubes as an indicator of ATP levels. Mixtures of uncoupled and coupled mitochondria were made and compared with the mitochondria damaged by ischemia. The results showed that mitochondria damaged by prolonged ischemia hydrolyze ATP more rapidly than normal mitochondria; however, normal mitochondria can easily compensate for increased ATP hydrolysis when in mixture with equal amounts of uncoupled mitochondria. These data suggests that the low cellular levels of ATP following irreversible ischemia are primarily due to decreased ATP synthesis and not to increased hydrolysis.     

Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.      

Long-term culture of human aortas

Summary Segments of human thoracic aorta were maintained in long-term explant culture for 18 weeks in serum-supplemented medium. The aortas were grossly normal in appearance, and random samples fixed for light microscopy prior to culture revealed a normal morphology. The intima contained no more than five layers of smooth muscle cells. After 7 days in culture, the intima was noticeably thicker than the uncultured segments. The increased thickness was due to proliferating smooth muscle cells and production of extracellular material. After several months in culture, extracellular material consisting of collagen and flocculent material was present in areas resembling atherosclerotic fibrous plaques. A peripheral growth, which formed around the explant, was composed of fibroblastlike cells and added to the overall thickness of the intima. However, aortic segment maintained for up to 2 months in serum-free culture medium showed no cellular proliferation. This study demonstrates that changes resembling early stages of atherosclerosis occur in human aortas maintained in explant culture using routine culture procedures. Supported in part by the Pangborn Fund and the Graduate School of the University of Maryland. This is publication 443 from the Cellular Pathobiology Laboratory.     

Quantitative ökologische Analyse eines Rifflagunenareals bei Aqaba (Golf von Aqaba,Rotes Meer)

Following previous investigations on a fringing reef in the Red Sea near Aqaba (Mergner & Schuhmacher, 1974; Mergner & Svoboda, 1977) this paper presents a quantitative analysis of the faunal and floral stock in one of the selected test areas (5×5 m) located in the reef lagoon studied. During the observation period 237 macrobenthic species of 192 genera were found. Species numbers were 22 (algae), 18 (cnidarians), 22 (crustaceans), 113 (molluscs), 27 (echinoderms), 14 (fishes) and 21 (smaller animal taxa including foraminiferans, sponges, turbellarians, polychetes and ascidians). These numbers, though derived from a small and relatively monotonous reef area, exceed by far all data known from comparable reef zones. The ecological conditions as well as habitat preferences, times of occurrence, seasonal abundances, species diversities and dominances of the inhabitants observed in the test area are discussed. Comparisons of the population data of October, 1975 and March, 1976 indicate the influence of the succession, abundance and disappearance of the phytal on the environmental conditions of the mobile fauna, for example molluscs, echinoderms and fishes. The increase of some of its species, especially of juvenile individuals, is remarkable. Within the same period juvenile colonies of some xeniids and the stony coralStylophora pistillata undergo similar seasonal fluctuations; colonies eliminated by grazers or other, unknown circumstances, are replaced by new settlers. Altogether, the faunal and algal stock of this lagoon area can be interpreted as a climax community; its impressive density is apparently the result of a high number of various microhabitats. Each of these ecological niches provides manyfold living spaces for specific communities with different adaptive strategies. The highest number of species plus the highest diversity indices rank mostly among the mobile groups.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Two silicone nontoxic fouling release coatings: Hydrosilation cured PDMS and CaCO3 filled,ethoxysiloxane cured RTV11

Two silicone coatings have been evaluated for barnacle adhesion. One coating is an unfilled hydrosilation cured polydimethylsiloxane (PDMS) network, while the other is a room temperature vulcanized (RTV), filled, ethoxysiloxane cured PDMS elastomer, RTV11^?. The adhesion strength of one species of barnacle, Balanus eburneus, to the hydrosilation coatings is in the range of 0.37–0.60 kg cm^‐2 while the corresponding range for RTV11 is 0.64–0.90 kg cm^‐2. The easier release of B. eburneus from the hydrosilation cured network compared to RTV11 is discussed in relationship to differences in bulk and surface properties. Preliminary results suggest bulk modulus may be the most important parameter in determining barnacle adhesion strength. In light or mechanical property analysis, a re‐evaluation of surface properties and chemical stability is presented.     

Regulation of the Rev1–pol ζ complex during bypass of a DNA interstrand cross‐link

DNA interstrand cross‐links (ICLs) are repaired in S phase by a complex, multistep mechanism involving translesion DNA polymerases. After replication forks collide with an ICL, the leading strand approaches to within one nucleotide of the ICL (“approach”), a nucleotide is inserted across from the unhooked lesion (“insertion”), and the leading strand is extended beyond the lesion (“extension”). How DNA polymerases bypass the ICL is incompletely understood. Here, we use repair of a site‐specific ICL in Xenopus egg extracts to study the mechanism of lesion bypass. Deep sequencing of ICL repair products showed that the approach and extension steps are largely error‐free. However, a short mutagenic tract is introduced in the vicinity of the lesion, with a maximum mutation frequency of ~1%. Our data further suggest that approach is performed by a replicative polymerase, while extension involves a complex of Rev1 and DNA polymerase ζ. Rev1–pol ζ recruitment requires the Fanconi anemia core complex but not FancI–FancD2. Our results begin to illuminate how lesion bypass is integrated with chromosomal DNA replication to limit ICL repair‐associated mutagenesis.     

Targeting tumour necrosis factor alleviates signs and symptoms of inflammatory osteoarthritis of the knee

Introduction

Inflammation associated with synovial expression of TNFα is a recognised feature of osteoarthritis (OA), although no studies have yet reported beneficial effects of anti-TNFα therapy on clinical manifestations of inflammation in OA.

Methods

We conducted an open-label evaluation of adalimumab over 12 weeks in 20 patients with OA of the knee and evidence of effusion clinically. Inclusion criteria included daily knee pain for the month preceding study enrolment and a summed pain score of 125 to 400 mm visual analogue scale on the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain subscale. The primary outcome was the Osteoarthritis Research Society International/Outcome Measures in Rheumatology Clinical Trials (OARSI/OMERACT) response criterion at week 12. Secondary outcomes included the WOMAC pain score 20% and 50% improvement, WOMAC stiffness and function scores, patient and physician global visual analogue scale, as well as target joint swelling.

Results

Treatment was well tolerated and completed by 17 patients with withdrawals unrelated to lack of efficacy or adverse events. By intention to treat, an OARSI/OMERACT response was recorded in 14 (70%) patients. WOMAC pain 20% and 50% responses were recorded in 14 (70%) patients and eight (40%) patients, respectively. Significant improvement was observed in mean WOMAC pain, stiffness, function, physician and patient global, as well as target joint swelling at 12 weeks (P < 0.0001 for all). After treatment discontinuation, 16 patients were available for assessment at 22 weeks and OARSI/OMERACT response compared with baseline was still evident in 10 (50%) patients.

Conclusion

Targeting TNFα may be of therapeutic benefit in OA and requires further evaluation in controlled trials.

Trial registration

ClinicalTrials.gov: {"type":"clinical-trial","attrs":{"text":"NCT00686439","term_id":"NCT00686439"}}NCT00686439.