ROENTGEN DIAGNOSIS OF INTRA-ABDOMINAL HERNIA

The primary radiologic evidence of intra-abdominal hernia is disturbance of normal small intestine arrangement. Loops of intestine are crowded together as if in a bag, giving the appearance of clumping or sacculation. Dilatation and loss of mobility may occur with varying degrees of stasis. Displacement of viscera or pressure deformity may be observed.Studies of the small bowel are necessary to demonstrate these conditions and must be made with the patient in the erect as well as the horizontal position. Repeated studies may be required, and the best time to make them is during an acute attack, as the hernia may be temporarily reduced during a remission.The clinical symptoms are sufficiently characteristic to suggest the diagnosis in most cases. The usual history is of repeated attacks of abdominal pain or discomfort, usually accompanied by distention, varying in periodicity and intensity, with or without nausea or vomiting, and not accompanied by laboratory data or clinical signs indicative of inflammatory disease.Similar or identical clinical and roentgenologic evidence may be produced by torsion of the small bowel or by peritoneal adhesions.The hernia or torsion may reduce spontaneously before or at the time of operation. Therefore, a careful search for abnormal fossae, mesenteric defects or adhesive bands is necessary if herniation or torsion is not found.     

Biological interactions among extant and fossil clonal organisms

Biological interactions among clonal marine organisms are an important aspect of their behavior and are important in the construction of biological reefs. The interactions addressed here are among crustose and erect coralline algae, sponges, corals, and bryozoans, and may involve clones of the same species (conspecific), or different species (heterospecific). Conspecific interactions may be either between modules or clones that are produced asexually from one propagule, genetically identical, or between clones that are sexually produced from two or more propagules that may or may not be genetically identical. Juxtaposed genetically identical clones generally fuse whereas non-identical clones may or may not fuse, depending on their relatedness and histocompatibility. Most heterospecific clonal interactions are spatially competitive and result in overgrowths or stand-offs. Clone fission/fragmentation may occur as a result of biotic or abiotic processes that initially degrade but may eventually restore or even enhance ability to gain space and/or nutrients. Self-overgrowths also occur, usually over dead, diseased, or senescent parts of the same clone.     

Miliary tuberculosis presenting with hyponatremia and thrombocytopenia.

A 74-year-old woman with miliary tuberculosis had moderately severe hyponatremia due to inappropriate secretion of antidiuretic hormone (SIADH) and very severe thrombocytopenia without other hematologic abnormalities. She was treated with isoniazid, rifampin, ethambutol, prednisone, vincristine and fluid restriction and recovered completely. The SIADH may have been a response by the posterior pituitary to a decrease in intravascular volume resulting from the extensive pulmonary disease or associated hypoxia, or the tuberculous lung may have released ADH or an ADH-like substance. The thrombocytopenia may have resulted from a direct or indirect toxic effect of infection or, less likely, the tuberculosis may have activated latent idiopathic thrombocytopenic purpura.     

Causes and consequences of variation in competitive ability in plant communities

Abstract. Several factors may define the cause and pattern of variation in competitive ability among individuals within a plant community. Variation may be a consequence of genetic or environmental variability. These two sources of variation may vary in their relative magnitudes. The relevant scale of genetic variation may occur at the individual genotype level or at the species level. The relevant scale of environmental variation may occur at the individual plant level or at the neighbourhood (or community) level. Relative competitive abilities may be effected by genotype-environment interaction or by genotype-genotype (or species-species) interaction. The complex relationship among these factors reveals the mechanistic basis for establishing a clear distinction among five specific hypotheses for species coexistence and diversity that are all variations of the general hypothesis that competitive abilities do not differ sufficiently among coexisting species to cause any competitive exclusion at the community level. These hypotheses are compared in terms of the degree to which they are restricted by assumptions and supported by existing data, and in the extent to which they involve evolutionary consequences of competition.     

Thyroid hormone generalized resistance.

The syndromes of thyroid hormone resistance may affect overall or only some tissues. The generalized resistance is an inherited disease which involves a familial eumetabolic or hypometabolic goiter, increased free thyroid hormones with normal or elevated plasma TSH levels; children may present mental retardation, deafness, short stature and delayed bone age. The disease is frequently misdiagnosed. In vivo and in vitro tests may be used to assess the diagnosis. The defect of increment of sex hormone-binding globulin after administration of T3 may be useful in the demonstration of the disease. Therapy uses high T4 or T3 doses in hypometabolic patients. The generalized thyroid hormone resistance could be linked to abnormalities at the T3 receptor and c-erb A gene level, as a consequence of different point mutations or deletions involving the hormone-binding domain.     

THE PAROTID GLAND—A Reinterpretation of Its Anatomic Structure

The parotid gland does not have a constant size and shape and relationship to the facial nerve. It consists of two glandular masses, one lying on the masseter muscle and the other in the pterygoid space to a varying depth. These two masses are connected by a glandular bridge, either wide or narrow, which lies on the posterior border of the mandible. The course of the facial nerve may be through this connecting bridge or it may pass to one side or a branch may pass on either side. In passing forward, the nerve branches may lie wholly within the glandular mass on the masseter, wholly beneath it or partly within it and partly beneath it.     

Application of the serial sectioning and tridimensional reconstruction techniques to the morphological study of the Plasmodium falciparum mitochondrion

The use of serial sectioning followed by tridimensional reconstruction is a convenient way to study the spatial morphology of any structure (cell or organelle). This method was applied to the study of organelles of Plasmodium falciparum (FCR3) and enabled clarification of morphological features of the mitochondrion. The mitochondrion is polymorphic; in single sections it may be rounded, elongated or branched in shape. Its matrix may be dense or transparent, and it may or may not possess cristae. The 3-D reconstruction indicated that the mitochondrion is single in P. falciparum. Its form varies according to the age of the trophozoite. It becomes branched, and each lobe of the mitochondrion follows a daughter nucleus during the formation of merozoites.     

Lacto-Phenol Preparations

More or less permanent mounts of fungi, algae, root tips, epidermis, germinating spores, and other small objects may be made readily by transferring the material to Amann's lacto-phenol containing anilin blue, W. S. or acid fuchsin, used singly or mixed. The addition of 20 to 25% of glacial acetic acid to these mixtures is frequently advantageous; or material may be stained with various dyes—acid fuchsin, anilin blue, W. S. (cotton blue), rose bengal, phloxine, hematoxylin—in aqueous solutions containing 5% of phenol, and then mounted in lacto-phenol, 50% glycerin or phenolglycerin, depending on the dye used. The phenol solutions of acid fuchsin and anilin blue are acidified with acetic acid and those of rose bengal and phloxine are made slightly alkaline with ammonium hydroxide. The addition of ferric chloride to acid fuchsin or acidified hematoxylin may improve staining. Fixation may be preferable but may be omitted, especially with fungi. Formulae for the mounting media and ten staining mixtures are given.     

Doctors' rights and patients' obligations

Marshall examines arguments for and against physicians breaching their duty of confidentiality to persons diagnosed with HIV or AIDS by notifying third parties such as sexual partners or general practitioners who give care unrelated to HIV or AIDS. The arguments presuppose that the confidentiality right is not absolute, but may give way under certain circumstances. A physician's obligations to the larger community, for instance, may outweigh the obligation to keep a diagnosis of AIDS or HIV confidential. Marshall also argues that physicians who incur risks by treating patients with AIDS or HIV have a right to knowledge that will help them protect themselves. A patient with AIDS or HIV may be obliged to reveal this fact to physicians when seeking care for other health problems, or to allow the diagnosing physican to do so. These arguments may have implications for the debate over testing patients for AIDS or HIV without consent.     

The parotid gland; a reinterpretation of its anatomic structure

The parotid gland does not have a constant size and shape and relationship to the facial nerve. It consists of two glandular masses, one lying on the masseter muscle and the other in the pterygoid space to a varying depth. These two masses are connected by a glandular bridge, either wide or narrow, which lies on the posterior border of the mandible. The course of the facial nerve may be through this connecting bridge or it may pass to one side or a branch may pass on either side. In passing forward, the nerve branches may lie wholly within the glandular mass on the masseter, wholly beneath it or partly within it and partly beneath it.     

Influence of maternal infection on offspring resistance towards parasites

Immunoglobulins, parasite circulating antigens, immune cells, cytokines and other cell-related products can be transferred from infected mothers to their young. They can combine their effects to interact with the invading parasites, as well as to induce a long-term modulation of the offspring's capacity to mount an immune response to subsequent exposure to parasites. The protective effect of maternally derived antibodies may be limited by the selective transfer of immunoglobulin isotypes. Maternal antibodies may also prevent the priming of specific cells in offspring or inhibit the progeny's antibody production by interacting with B-cell receptors or with the idiotypic repertoire. The potentially beneficial priming effect of transferred parasitic antigens may be altered by the Th2-cell-biased foetal environment and such antigens may also induce deletion or anergy of T- and B-cell clones in offspring. Therefore, besides protective effects, maternal infection may downregulate the offspring's immune response. If such hyporesponsiveness may be clearly harmful (in increasing the risk or in worsening congenital or postnatally acquired infections in offspring), it can also be beneficial (in limiting the pathogenesis of some infections). Here, Yves Carlier and Carine Truyens review the rationale of these complex foeto-maternal relationships in parasitic diseases.     

Early development of the granule cell in the cerebellum of the chick embryo

The sequence of differentiation of the cerebellar granule cell in chick embryos from the eighth to the 15th days of incubation has been studied in Golgi-stained celloidin sections. In the germinal-cell phase, the presumptive granule cell sends out one or two horizontal processes which may originate either in the body of the cell or in the extension which attaches it to the pial surface. Thus the germinal cell may be converted into either a monopolar or a bipolar presumptive granular cell. Bipolar cells may have two processes of the same length (symmetrical cells) or of unequal length (asymmetrical cells). In the symmetrical as well as asymmetrical bipolar cells the leading process is formed, by means of which the perikaryon emigrates until it situates itself definitely in the internal granular layer. Thus, symmetrical and asymmetrical bipolar cells give rise to a granule cell with parallel fibers of equal or different lengths. The monopolar element may originate a second process or may remain in the monopolar phase until it reaches the internal granular layer. Once there, it completes the formation of the parallel fibers.     

Habitat and food specificity in aphidophagous predators

Current knowledge of the processes underlying prey location and choice by aphidophagous predators is reviewed by considering the succession of behavioural mechanisms required for the predator to obtain prey. The predator may locate areas where prey are likely to be found by responding to physical aspects of the habitat, or to semiochemicals produced by the host plant. The predator may then respond to visual or olfactory cues to locate the aphid prey. The predator's readiness to attack and consume aphids is influenced by any behavioural or chemical defence strategies, and by the palatability or nutrient value of the aphids. Toxic allelochemicals ingested by aphids from their host plant may have a detrimental effect on predators.     

COMMON EYE PROBLEMS IN CHILDREN

Most penetrating or lacerating injuries of the eye in children justify examination under anesthesia to avoid further harm to an uncooperative patient. The pediatrician in doubt should merely apply a sterile dressing and have an ophthalmologist examine the injury in hospital. Nonperforating injuries may result in severe bleeding 48 to 72 hours later; this may be averted by bandaging the eyes and maintaining rest for four or five days. Removal of foreign bodies should be followed by application of antibiotic ointment and patching to prevent contamination.Congenital stenosis of the lacrimal duct may clear spontaneously or through application of decongestants and sympathomimetic drops. More severe effects, especially infection, justify probing at six months or earlier. The operation should be done under general anesthesia, preferably in hospital.Acute conjunctivitis is best treated by local application of antibiotics or sulfonamides only. Chronic infections may be better managed with the addition of corticosteroids, which reduce local inflammation and control bacterial reaction. Bacterial study should be done only if empirical antibiotic therapy fails. Bacterial desensitization may be helpful. The same methods are effective in blepharitis, aided by hygienic measures. Corticosteroids are most useful in allergic inflammations.Refractive difference is difficult to test before a child can read, and apparent defects may be due to lack of cooperation. Marked inequality of the eyes may signify organic disorder. Strabismus, on the other hand, can be detected as early as 12 or 15 months and should be treated as early as possible by proper lenses, surgery, or both. Pediatricians and parents should be aware that many children appear to have strabismus because of wide epicanthi and deep-set eyes.     

Theoretical aspects of neuroplasticity.

The authors propose an integrative theory of the organization of neuroplastic processes. Neuroplasticity is assumed to be one of the essential characteristics of the nervous tissue which may be manifested comparatively rapidly and result in reversible changes (functional plasticity). It may also modulate the expression of genotype into phenotype (adaptation) and thus bring about long-lasting effects. Neuroplastic mechanisms are triggered by various natural or artificial stimuli, which may arise in the internal or external environment, and they may differ quantitatively or qualitatively. The effects of plasticity can lead to either positive or negative changes during development (evolutionary plasticity), after short-term exposition (reactive plasticity), after long-term or continuous stimuli (adaptational plasticity), and during functional or structural recovery of damaged neuronal circuits (reparation plasticity). Manifestations of plasticity have probably the same basis, irrespective of the cause which triggered them or the brain region where they were accomplished. Neuroplastic mechanisms are based on the modulation of signal transmission across synapses. They can be related to interneuronal relations. The resulting changes may occur in the communication between neurons (synaptic level), in the activity of local neuronal circuits (at the level of local circuits) or in the relations between individual functional brain systems (multimodular level).     

Sexual maldevelopment and sex reversal, chromosomal causes

The SRY gene on the Y chromosome is the testis determining factor (TDF). It is therefore the initial male determining factor. However, phenotypic sex determination includes a cascade of genes located on autosomes as well as sex chromosomes. Aberrations of these genes may cause sexual maldevelopment or sex reversal. Abnormalities may include single gene mutations and gene loss or gain-changes may involve only sex organs or may be part of syndromes. These changes may also arise as chromosome abnormalities involving contiguous genes. Eight cases with chromosomal abnormalities involving different causative mechanisms are described herein. The most common cause is nondisjunction, including loss or gain of sex chromosomes. Less common causes are mispairing and crossing over in meiosis, chromosome breaks with repair, nonhomologous pairing due to low copy repeats and crossing over, and translocation (familial or de novo) with segregation. Cases include: [see: text].     

Germ cell sex determination

Whether a germ cell embarks on oogenesis, the female gametogenic pathway, or spermatogenesis, the male pathway, may be determined cell-autonomously, by the germ cell's own genes, or by the tissue environment in which it is located. The decision may or may not be associated with the time of entry into meiosis, and this in turn may be controlled wholly by the germ cell's own genes, or in part by the environment. These issues will be explored with reference to Caenorhabditis elegans, Drosophila and the mouse.     

Patterns of constriction produced by vasoactive agents

The patterns of vasoconstriction produced by local infusions of constrictor agents and neurogenic stimuli are unique and varied. Although vasoconstrictors or neurogenic stimuli may produce similar increases in total resistance to blood flow, the effects on consecutive vascular segments may differ dramatically. Vasoconstrictors may affect primarily small vessels, large vessels, or a combination of both. The constrictor response may be restricted to precapillary vessels or may recruit both pre- and postcapillary vessels. The baroreceptors elicit a pattern of vasoconstriction distinct from that produced by electrical stimulation of a vasomotor nerve. Prearteriolar and venous resistance may contribute more than arterioles to increases in total vascular resistance produced by local infusions of vasoconstrictor agents or nerve stimulation. The constriction of large vessels also affects fluid filtration, vascular capacity, and the distribution of blood flow between shunt and exchange vessels. The waning of the resistance increase that occurs during prolonged infusions of vasoconstrictors varies, in part, as a function of the vessel segments that participate in the vasoconstrictor response. Large vessels participate in vasoconstrictor responses triggered by stimuli that impose a severe stress on the circulation. In contrast, small vessels participate primarily in normal vascular adjustments required to maintain blood pressure at the set point.     

PACEMAKERS IN NITELLA : III. ELECTRICAL ALTERNANS

An electrical impulse traveling along a Nitella cell may produce a complete or a partial response. The two kinds of response may occur in regular alternation. The partial response varies greatly and may be so far reduced as to appear as a local thickening in the upstroke of the action curve, usually accompanied by a more or less pronounced hump. In consequence a considerable variety of action curves is produced. The observations show that different regions of the cell may react differently.     

The exploitation of mutualisms

Mutualisms (interspecific cooperative interactions) are ubiquitously exploited by organisms that obtain the benefits mutualists offer, while delivering no benefits in return. The natural history of these exploiters is well-described, but relatively little effort has yet been devoted to analysing their ecological or evolutionary significance for mutualism. Exploitation is not a unitary phenomenon, but a set of loosely related phenomena: exploiters may follow mixed strategies or pure strategies at either the species or individual level, may or may not be derived from mutualists, and may or may not inflict significant costs on mutualisms. The evolutionary implications of these different forms of exploitation, especially the threats they pose to the stability of mutualism, have as yet been minimally explored. Studies of this issue are usually framed in terms of a "temptation to defect" that generates a destabilizing conflict of interest between partners. I argue that this idea is in fact rather inappropriate for interpreting most observed forms of exploitation in mutualisms. I suggest several alternative and testable ideas for how mutualism can persist in the face of exploitation.