Does a torn anterior cruciate ligament lead to change in the central nervous drive of the knee extensors?

Integrated surface electromyograms of the three superficial parts of the quadriceps and isokinetic knee extensor maximum torque and power production were recorded simultaneously and at different angular velocities in both legs in 11 male subjects with unilateral tear of the anterior cruciate ligament. The cross-sectional area (CSA) of the thigh and its muscular components were measured by computerized tomography. The principal findings were a small but significant decrease in quadriceps CSA on the affected side; a decreased active, but not passive, range of movement; decreased mechanical output, whether or not corrected for differences in CSA; and decreased electromyographic activity--particularly in rectus femoris. These findings suggest that the reason for the decreased maximum and total knee extensor performance seen in these patients is a change in knee joint receptor afferent inflow.     

Filtering of behaviourally relevant temporal parameters of a grasshopper's song by an auditory interneuron

Summary In females of the acridid grasshopperChorthippus biguttulus, thoracic auditory interneurons were investigated with respect to their selectivity for temporal parameters of the conspecific song. Special attention was given to the detection of small gaps in the syllables of the song, since behavioural experiments have shown that the presence or absence of gaps is critical for the female's Innate Releasing Mechanism (cf. Fig. 1).The spiking response of one ascending interneuron, the AN4, shows filtering properties which closely resemble the behavioural reactions (cf. Figs. 1, 3 and 5b). The difference in the AN4's reaction to stimuli with gaps and uninterrupted stimuli is maintained over the behaviourally relevant intensity range (Fig. 4). This reaction is reliable enough that the stimulus type could be inferred by higher centres even from single stimulus presentations. Hence, this neuron is likely to participate in the task of gap detection and probably is a part of the neuronal filter network which determines the characteristics of the Innate Releasing Mechanism of this species. However, this interneuron is not species-specific: A homologue exists in other acridids as well and, inLocusta migratoria, has similar response characteristics (Fig. 6). The inferences of this observation for the evolution of an Innate Releasing Mechanism are discussed.Abbreviations CNS central nervous system - PST-histogram post-stimulus-time-histogram - SPL sound pressure level - IRM Innate Releasing Mechanism     

Anaerobic degradation of hydroaromatic compounds by newly isolated fermenting bacteria

Aerobic organisms degrade hydroaromatic compounds via the hydroaromatic pathway yielding protocatechuic acid which is further metabolized by oxygenase-mediated ring fission in the 3-oxoadipate pathway. No information exists on anaerobic degradation of hydroaromatics so far. We enriched and isolated from various sources of anoxic sediments several strains of rapidly growing gram-negative bacteria fermenting quinic (1,3,4,5-tetrahydroxy-cyclohexane-1-carboxylic acid) and shikimic acid (3,4,5-trihydroxy-1-cyclohexene-1-carboxylic acid) in the absence of external electron acceptors. Quinic and shikimic acid were the only ones utilized of more than 30 substrates tested. The marine isolates formed acetate, butyrate, and H₂, whereas all freshwater strains formed acetate and propionate as typical fermentation products. Aromatic intermediates were not involved in this degradation. Characterization of the isolates, fermentation balances for both hydroaromatic compounds, and enzyme activities involved in one degradation pathway are presented.Abbreviations BV benzyl viologen (1,1-dibenzyl-4,4-bipyridinium dichloride) - CoA coenzyme A - CTAB cetyltrimethylammonium bronide - DCPIP 2,4-dichlorophenolindophenol - DTT 1,4-dithiotheriol - MV methyl viologen (1,1-dimethyl-4,4-bipyridinium dichloride) - Tricine N-[tris-(hydroxymethyl)-methyl]-glycine - Tris tris-(hydroxymethyl)-aminomethane     

The primary structure and oxygen-binding properties of the single haemoglobin of the high-Antarctic fish Aethotaxis mitopteryx DeWitt

Summary The complete amino acid sequence of the single haemoglobin of the Antarctic fish Aethotaxis mitopteryx DeWitt has been established by automated repetitive Edman degradation on the intact and cleaved (enzymatically and chemically) and chains. A very high sequence identity with other Antarctic fish haemoglobins has been detected. The haemoglobin has a moderate Bohr effect and no Root effect. Organic phosphates and chloride also regulate oxygen binding only to a moderate extent. The lack of Root effect is consistent with the substitution His — Val at the HC3 C-terminal position of the chain. The low overall heat of oxygenation suggests that in this species oxygen transport is an energy-saving process, presumably related to cold adaptation. The comparative analysis of the haemoglobins of Antarctic fishes emphasises some unique features of the oxygen-transport system of A. mitopteryx, which are likely to be related to its also rather unique mode of life.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation     

The gene for dominant white color in the pig is closely linked to ALB and PDGRFRA on chromosome 8.

White is a widespread coat color among domestic pig breeds and is controlled by an autosomal dominant gene I. The segregation of this gene was analyzed in a reference pedigree for gene mapping developed by crossing the European wild pig and a Large White domestic breed. The gene for dominant white color was shown to be closely linked to the genes for albumin (ALB) and platelet-derived growth factor receptor alpha (PDGFRA) on chromosome 8. An unexpected phenotype with patches of colored and white coat was observed among the F1 and F2 animals. The segregation data indicated that the phenotype was controlled by a third allele, denoted patch (Ip), most likely transmitted by one of the Large White founder animals. It is shown that the ALB, PDGFRA, I linkage group shares homologies with parts of mouse chromosome 5, human chromosome 4, and horse linkage group II, all of which contain dominant genes for white or white spotting. Candidate genes for the dominant white and patch mutations in the pig are proposed on the basis on these linkage homologies and the recent molecular definition of the dominant white spotting (W) and patch (Ph) mutations in the mouse.     

Isolation and characterization of high-mobility-group proteins from maize

Chromosomal nonhistone high-mobility-group (HMG) proteins were purified from nuclei of maize (Zea mays L. cv. A619) endosperm and leaf tissue. Tissuespecific differences were observed in their polypeptide patterns, in in-vitro phosphorylation experiments with a casein-kinase type II, and by Western blot analysis with antisera against different HMG proteins. Gelfiltration chromatography demonstrated that maize HMG proteins occur as monomers. By measuring the capacity of the HMG proteins to bind to the 5 flanking region of a zein gene, the sensitivity of the proteins to different temperatures, salt concentrations and pH values was determined.Abbreviations EMSA electrophoretic-mobility-shift assay - FPLC fast protein liquid chromatography - HMG high-mobility group - kDa kilodaltons - PVDF polyvinylidenedifluoride - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis We would like to thank Mrs. E. Brutzer for excellent technical assistance. We are indebted to Mrs. M. Strecker and Dr. W. Bessler of the Institut für Immunbiologie, Freiburg, FRG, for the preparation of antisera and we gratefully acknowledge helpful discussions with Drs. T. Quayle, R. Grimm and U. Müller of this institute. This work was supported by grants from the Deutsche Forschungsgemeinschaft and the Fond der Chemischen Industrie.     

Specific eradication of micrometastases by transfer of tumour-immune T cells from major-histocompatibility-complex congenic mice

Summary DBA/2 (H-2^d) mice bearing a transplanted highly metastatic lymphoma (ESb) in a state of widely disseminated disease could be successfully treated by a combination of surgery (removal of the local tumour), irradiation (5 Gy) and adoptive immunotherapy. The immunotherapy was achieved by transfer of anti-ESb-immune spleen cells from B10.D2 mice, which express the same major histocompatibility complex (MHC) molecules as DBA/2. In contrast, anti-ESb-immune cells from MHC-disparate C57BL/6 mice did not confer protective immunity. The B10.D2 anti-ESb-immune T cells contain two types of cytolytic specificity as detected by limiting-dilution analysis: (1) clones with specificity for the ESb-tumour-associated transplantation antigen (TATA) (at low frequency), and (b) clones with specificity for minor DBA/2 histocompatibility (H) antigens (at high frequency). Immune B10.D2 cells raised against different tumour lines or against TATA^– ESb tumour variants did not confer the 100% protection seen with immune cells against ESb TATA⁺ cells. Finally we demonstrate that the allogeneic immune cells are more potent in terms of protective immunity than corresponding syngeneic immune cells. The data suggest that the strong graft-versus-leukemia effect with immune T cells from allogeneic MHC-identical but not from MHC-disparate mice was due to T cells with MHC-restricted specificity for an ESb-associated TATA. A graft-versus-host reactivity that developed much later and could not be prevented was most likely due to T cells sensitized against normal minor H antigens of the host. Our results are of potential relevance for allogeneic bone marrow transplantation and adoptive immunotherapy protocols.     

Hypothermic effects on action potential and force production of hedgehog and guinea pig papillary muscles

Action potentials and isometric force were recorded in papillary muscles from guinea pigs and summer hedgehogs at different temperatures between 37 and 0 degrees C. The action potential of the hedgehog was of a lower amplitude (mean 83 +/- 6 mV) than that of the guinea pig (mean 110 +/- 5 mV). The action potential duration at 50% repolarization was 22 +/- 2 msec in the hedgehog as compared to 105 +/- 11 msec in the guinea pig. Moreover, there was no distinct plateau phase of the hedgehog action potential. Lowering temperature prolonged the action potential duration in the two preparations by about the same percentage. However, the guinea pig preparation became progressively less excitable below 20 degrees C. Lowered temperature produced a positive inotropic effect in the guinea pig, whereas this effect was very slight in the hedgehog heart. Postextrasystolic potentiation was seen in the guinea pig but not in the hedgehog preparation. It is suggested that this difference between the preparations may be due to a greater relative amount of activator calcium in the hedgehog heart. The difference in cold tolerance between the preparations may reflect a difference in chemical composition of the sarcolemma.     

Temporal fluctuations of silver,copper and zinc in the bivalve Macoma balthica at five stations in South San Francisco Bay

Concentrations of Cu, Ag and Zn were measured in the soft tissues of the estuarine bivalve Macoma balthica in South San Francisco Bay at near-monthly intervals for periods of two to three years at four stations, and eight years at a metal-enriched station. The amplitude and frequency of fluctuations differed among stations and among metals. Fluctuations were greatest at stations with the greatest metal enrichment and with the least dilution and flushing of wastes. A consistent seasonal pattern of fluctuation in Cu and Ag concentrations was evident in M. balthica at the metal-enriched station. These seasonal changes in tissue metal concentrations appeared to be affected by metal inputs, hydrologic processes that may affect both metal concentrations and bioavailability, and seasonal changes in the weight of the bivalve. The contributions of each of these interacting factors could not be determined quantitatively. At the metal-enriched station significant variation in the amplitude of seasonal fluctuations was also evident from year to year. Interpretation of metal concentrations in bivalves from estuaries will require careful consideration of the processes which affect metal dynamics in these complex environments.