Athletic aids: fact or fiction?

A major problem facing physicians involved in the daily care of amateur athletes in international competition is that of so-called doping. While there are many substances used that might be considered ineffectual or physiologic, the two main categories of substances considered as doping agents are stimulants and anabolic steroids. No substance is as yet known that will improve an athlete''s performance. Often such substances are taken in error rather than in a misguided attempt to improve one''s ability. These substances can be dangerous and, because of this, doping rules were established basically to protect the athlete. Anabolic steroids are particularly dangerous; they usually are taken by those engaged in lifting or throwing sports in an attempt to improve performance by increasing muscle bulk. There is as yet no scientific proof that performance is improved. Dope testing for stimulants should be carried out in a quantitative rather than qualitative manner so that the athlete who has taken a small amount of a so-called stimulant (such as an asthma or common cold preparation) would not be excluded from competition. Rigid testing for anabolic steroids should be continued.     

AIDS in Africa: distinguishing fact and fiction

The data widely purporting to show the existence and heterosexual transmission in Africa of a new syndrome caused by a retrovirus which induces immune deficiency are critically evaluated. It is concluded that both acquired immune deficiency (AID) and the symptoms and diseases which constitute the clinical syndrome (S) are of long standing in Africa, affect both sexes equally and are caused directly and indirectly by factors other than human immunodeficiency virus (HIV). Seropositivity to HIV in Africans usually represents no more than cross-reactivity caused by an abundance of antibodies induced by the numerous infectious and parasitic diseases which are endemic in Africa. The apparently high prevalence of AIDS and HIV seropositives is therefore not surprising and is not proof of heterosexual transmission of either HIV or AIDS.E. Papadopulos-Eleopulos is with the Department of Medical Physics, The Royal Perth Hospital, Perth 6000, Western Australia, Australia; V.F. Turner is with the Department of Emergency Medicine, The Royal Perth Hospital, Perth 6000, Western Australia, Australia, J.M. Papadimitriou is with the Department of Pathology, University of Western Australia, Perth, Western Australia. H. Bialy is with Bio/Technology, 65 Becker St, New York, NY 10012, USA.     

A marine refugium in Iceland during the last glacial maximum: fact or fiction?

Although several authors have postulated coastal ice-free areas during the last glacial maximum in Iceland, where some species may have survived, the geological evidence strongly indicates that there were none. Also, the species involved are mostly not found in the high arctic today, and are therefore unlikely to have endured conditions in frigid glacial refugia.     

Brain-size,grey matter and race —fact or fiction?

A critical review is given of those factors which may be accompanied by variations in brain weight, viz. sex, body size, age of death, nutritional state in early life, source of the sample, occupational group, cause of death, lapse of time after death, temperature after death, anatomical level of severance, presence or absence of cerebrospinal fluid, of meninges, and of blood-vessels. Valid comparisons between the brain-weight of human populations should take all, or several, of these variables into account; however, published studies have not done so, despite claims to the contrary. The ideal sample is from subjects who have died suddenly without prior disease: while three such samples are on record for Europeans, none has been recorded for Negroes. The brain-weight of healthy Negroes is not known. Most published interracial comparisons are invalid. The histological, chemical and functional counterparts of big and small brains in modern man are not known. Published interracial comparisons of thickness of the cerebral cortex and, particularly, of its supragranular layer, are technically invalid: there is no acceptable proof that the cortex of Negroes is thinner in whole, or in any layer, than that of Europeans. It is concluded that vast claims have been based on insubstantial evidence.     

Worker rehabilitation programs. Separating fact from fiction.

A few worker rehabilitation programs have had outstanding success in improving ability to function for persons with occupational back pain. Local programs must show that they have similar success. Because the definitions of terms such as "back school," "work hardening," and "functional restoration" are blurred at a local level, the choice of a program for an individual patient must depend primarily on the program''s demonstrated success rate with similar patients. The chances of returning to work decrease as a function of time after injury. Therefore, referring physicians, insurers, and employers must be provided with information regarding results in terms of acute (0 to 6 weeks), subacute (7 to 12 weeks), and chronic (more than 12 weeks) back pain. Other important variables include selection criteria, program cost, and dropout rate. We advocate standardized reporting of such data for all worker rehabilitation programs. A model "report to consumers," described here, is a minimal obligation. The validity of a number of important internal quality assurance issues is uncertain. Ethical and legal pressures must be recognized.     

Plasmatubules: fact or artefact?

Plasmatubules are tubular evaginations of the plasmalemma associated with sites where high solute flux occurs between apoplast and symplast. Plasmatubules of the scutellar epithelial cells of germinating barley (Hordeum vulgare L.) have been examined following a variety of fixation methods. Of the aqueous fixations, primary aldehyde fixation with osmium post-fixation and osmium as the primary fixative gave comparable images, whilst potassium permanganate resulted in some distortion of the tissue in general including dilation of the tubular evaginations of the plasmalemma. Freeze-fixation and substitution with acetone and acetone-osmium gave images of the plasmalemma comparable to those obtained by the aqueous aldehyde and osmium methods. The similarity of structure with aldehyde or osmium and freezing as the primary fixation is taken to indicate that plasmatubules are real and not artefacts resulting from the fixation procedure.     

Organ printing: fiction or science

Aggregates of living cells (i.e. model tissue fragments) under appropriate conditions fuse like liquid drops. According to Steinberg's differential adhesion hypothesis (DAH), this may be understood by assuming that cells are motile and tissues made of such cells possess an effective surface tension. Here we show that based on these properties three-dimensional cellular structures of prescribed shape can be constructed by a novel method: cell aggregate printing. Spherical aggregates of similar size made of cells with known adhesive properties were prepared. Aggregates were embedded into biocompatible gels. When the cellular and gel properties, as well as the symmetry of the initial configuration were appropriately adjusted the contiguous aggregates fused into ring-like organ structures. To elucidate the driving force and optimal conditions for this pattern formation, Monte Carlo simulations based on a DAH motivated model were performed. The simulations reproduced the experimentally observed cellular arrangements and revealed that the control parameter of pattern evolution is the gel-tissue interfacial tension, an experimentally accessible parameter.