Antibody-dependent cellular cytotoxicity-inducing antibodies against human immunodeficiency virus. Presence at different clinical stages

The presence of antibodies mediating antibody-dependent cellular cytotoxicity (ADCC) against human immunodeficiency virus (HIV)-infected target cells was investigated with 170 sera from patients with varying severity of HIV infection. Approximately 40% of sera from individuals representing all stages of infection were ADCC-positive when tested against HTLV-IIIB infected 0937 clone 2 target cells. The positive sera had higher HIV antibody titers as measured by enzyme-linked immunosorbent assay compared with ADCC-negative sera. ADCC titers were lower in patients with acquired immune deficiency syndrome than in asymptomatic carriers. This decline in ADCC titer was not correlated with a general decrease of HIV antibodies. No correlation between the CD4:CD8 lymphocyte ratio and ADCC activity was found. The possible beneficial effect of ADCC-inducing antibodies early in infection is discussed in relation to the effect of ADCC-inducing antibodies in other retrovirus systems and to the nature of lentivirus infections.     

Eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man

The primary purpose of this investigation was to study the eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man using a recently developed combined isometric, concentric and eccentric controlled velocity dynamometer (the SPARK System). A secondary purpose was to compare the method error associated with maximal voluntary concentric and eccentric torque output over a range of testing velocities. 21 males (21-32 years) performed on two separate days maximal voluntary isometric, concentric and eccentric contractions of the quadriceps femoris at 4 isokinetic lever arm velocities of 0 degree.s-1 (isometric), 30 degrees.s-1, 120 degrees.s-1 and 270 degrees.s-1. Eccentric peak torque and angle-specific torques (measured every 10 degrees from 30 degrees to 70 degrees) did not significantly change from 0 degrees.s-1 to 270 degrees.s-1 (p greater than 0.005) with the exception of angle-specific 40 degrees torque, which significantly increased; p less than 0.05). The mean method error was significantly higher for the eccentric tests (10.6% +/- 1.6%) than for the concentric tests (8.1% +/- 1.7%) (p less than 0.05). The mean method error decreased slightly with increasing concentric velocity (p greater than 0.05), and increased slightly with increasing eccentric velocity (p greater than 0.05). A tension restricting neural mechanism, if active during maximal eccentric contractions, could possibly account for the large difference seen between the present eccentric torque-velocity results and the classic results obtained from isolated animal muscle.     

Comparison by Gas-Liquid Chromatography of the Fatty Acids of Mycobacterium avium and Some Other Nonphotochromogenic Mycobacteria

Fifty-eight strains of nonphotochromogenic mycobacteria representing nine different serotypes were studied, including 38 strains of Mycobacterium avium and 20 strains of Battey bacilli. The lipids were extracted from whole cells, saponified with potassium hydroxide, and esterified with diazomethane. The fatty-acid profiles determined by gas-liquid chromatography included saturated fatty acids ranging from C(8) to C(24), plus some unsaturated analogues and a branched-chain acid. No consistent differences in the fatty-acid profiles were observed between strains of M. avium and Battey bacilli. Quantitative differences in the means (significant at P < 0.01) were observed in the relative amounts of 14:0, 16:1, 18:0, 18:1, and a branched-chain acid among strains of the same serotype. We were unable to differentiate the fatty-acid profiles of recently isolated strains or those maintained in culture for more than 2 years.     

Destruction of Various Kinds of Mycobacteria in Milk by Pasteurization

Various strains of unclassified mycobacteria, Mycobacterium tuberculosis (including H37Rv strains), M. bovis, M. avium, M. fortuitum, and bacille Calmette-Guerin, were exposed to the temperature and time of pasteurization in skim milk in test tubes. Of the 195 strains tested, there were a few surviving colonies among 6 of 33 skotochromogens, 1 of 26 photochromogens, 10 of 79 nonchromogens, and 1 of 9 rapid growers. Subcultures of the surviving colonies failed to resist the pasteurization tests on subsequent trials.     

Predation and space utilization patterns in a marine epifaunal community

The relative abundance patterns of several sessile epifaunal species occurring subtidally on large artificial substrata (pilings) were examined under experimental conditions involving the manipulation of densities of the echinoid Arbacia punctulata (Lamarck). The foraging activities of this predator could denude the substratum of most species with notable exceptions including the colonial hydroid Hydractinia echinata Fleming and the sponge Xestospongia halichondroides (Wilson). Moreover, these were the only two of the twenty most common species which did not significantly change in relative abundance over the experimental period. Both species had low recruitment rates and were commonly associated with substrata which had been submerged for several years. Neither species aggressively interacted with adjacent spatial competitors but instead, appeared to employ a defensive space utilization ‘strategy’. Provision of unoccupied substrata by Arbacia was apparently the major factor favoring both recruitment and growth of Hydractinia, which covered up to 30% of the area on the oldest pilings. More recently submerged substrata were covered by species such as Schizoporella errata (Waters) which had a much higher recruitment rate but was commonly overgrown by several other species. Recruitment rate, competitive ability, and vegetative growth are discussed in terms of the size of the substratum and the possibility of biased sampling in fouling studies. The widespread introduction of large artificial substrata into the natural environment has considerably altered the structure of the natural habitat and constitutes a potentially important selective force for changes in settlement preferences, especially among species such as Hydractinia which persist and become abundant on these substrata.     

Recruitment and local persistence of a freshwater bryozoan in stream riffles

Recruitment in clonal organisms often involves both sexual and asexual processes whereby new individuals are added to adult populations. During 1988–1990,1 examined local distribution and abundance patterns, substrate colonization, and recruitment in riffle populations of the freshwater bryozoan Plumatella emarginata. Abundance levels of P. emarginata at eight selected study sites were strongly dependent on substrate size but not on overall substrate availability or stream position. Colonization of large, P. emarginata-free substrates at one site resulted in an aggregated dispersion pattern of short-lived colonies and the production of locally persistent sessoblasts. Sessoblast production rates were dependent of colony size and number. However, the estimated single season rates of colonization and recruitment were insufficient to account for the high resident population on large substrates. I conclude that sessoblast persistence is essential for escaping mortality and promoting future recruitment and local population growth and that the population dynamics of P. emarginata are strongly nonequilibrial being influenced by unpredictable disturbances as well as by rates of recruitment which increase with local density.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.