Bicycle helmet use by adults: the impact of companionship.

Most of the nearly 1,000 fatal bicycle-related injuries annually could be prevented if riders used safety helmets. Helmet use by adult bicyclists has received relatively little attention because educational campaigns to promote helmet use generally focus on children. Helmet use by adult and child bicyclists at 120 suburban and rural sites in three Maryland counties was observed on two Saturdays in 1990-91 during an evaluation of the impact of a mandatory helmet law. Concordance or discordance of helmet use within various groups of bicyclists--adults only, adults with children, and children only--was recorded. Helmet use among 2,068 adult bicyclists was 49 percent, 51 percent, and 74 percent in the three counties. In two counties combined, 52 percent (365 of 706) of solo adult bicyclists wore helmets compared with only 5 percent (5 of 94) of solo child bicyclists (P < .001). Helmet use or nonuse was concordant among 87 percent of 277 adult-adult pairs, 94 percent of 50 child-child pairs, and 91 percent of 32 adult-child pairs of bicyclists observed. Concordance rates of helmet use or nonuse were similarly high among pairs of adult bicyclists of the same or mixed sexes. These data are consistent with the concept that both adults and children tend to adopt the helmet-wearing behaviors of their companions. Public health efforts focused on adults should encourage helmet use by adult bicyclists both to prevent head injuries and to provide a role model for children.     

Head injuries incurred by children and young adults during informal recreation.

To examine injuries related to playground equipment, children's vehicles, roller skates, and skateboards, 1991 data on emergency room patients younger than 25 years in the Consumer Product Safety Commission's 91 surveillance hospitals were used. Head injury was the primary diagnosis for an estimated 58,480 patients, exceeding the total number of head injuries to bicyclists younger than 25 years. The head injury rate decreased with age. The large number and high rate of head injuries in children involved in a variety of recreational activities suggests the value of multipurpose helmets.     

Patellofemoral joint: kinematic MR imaging to assess tracking abnormalities

The patellofemoral joint was imaged with magnetic resonance (MR) in the axial plane while the knee was positioned from 0 degrees to 32 degrees of flexion (nine positions). These multiple sequential images obtained within the early phases of flexion of the knee were viewed in a "cine-loop" format, producing a kinematic study that clearly demonstrated the relationship of the patella to the trochlear groove. Four healthy subjects and one patient with known bilateral subluxing patellae were studied. The preliminary results suggest that kinematic MR imaging of the patellofemoral joint is potentially useful for the evaluation of patellar tracking abnormalities.     

Tissue-specific tumor suppressor activity of retinoblastoma gene homologs p107 and p130

The retinoblastoma gene family consists of three genes: RB, p107, and p130. While loss of pRB causes retinoblastoma in humans and pituitary gland tumors in mice, tumorigenesis in other tissues may be suppressed by p107 and p130. To test this hypothesis, we have generated chimeric mice from embryonic stem cells carrying compound loss-of-function mutations in the Rb gene family. We found that Rb/p107- and Rb/p130-deficient mice were highly cancer prone. We conclude that in a variety of tissues tumor development by loss of pRB is suppressed by its homologs p107 and p130. The redundancy of the retinoblastoma proteins in vivo is reflected by the behavior of Rb-family-defective mouse embryonic fibroblasts in vitro.     

The Role of Cathepsin D in the Pathogenesis of Tuberculosis: A Histochemical Study Employing Unlabeled Antibodies and the Peroxidase-Antiperoxidase Complex

Cathepsin D was visualized in free pulmonary alveolar macrophages (AM), in oil-induced peritoneal macrophages (MN) and in rabbit pulmonary and dermal BCG lesions with unlabeled antibodies and the peroxidase-antiperoxidase (PAP) complex. Large amounts of cathepsin D were present in AM and lower amounts in MN. In the lung this enzyme was richest in the alveolar macrophages that accumulated around the BCG lesions. In the dermal lesions, cathepsin D was in highest concentration in macrophages at the border of the necrotic (liquefying) centers. It was also found in high concentration in keratinizing cells of the dermal epithelium and hair follicles. It did not, however, increase appreciably in many of the activated macrophages that stained intensely for the lysosomal enzyme β-galactosidase. In fact, many epithelioid cells with high β-galactosidase activity contained no visible cathepsin D. This proteinase does not, therefore, seem to be primarily involved in the lymphocyte-mediated macrophage activation associated with acquired cellular resistance to tubercle bacilli. It is probably more involved with cell autolysis, with the digestion of ingested necrotic debris and, in all likelihood, with the process of liquefaction, the most adverse event in the pathogenesis of tuberculosis in man.     

Effects of dexamethasone and transient malnutrition on rabbits infected with aerosolized Mycobacterium tuberculosis CDC1551

Malnutrition is common in the developing world, where tuberculosis is often endemic. Rabbits infected with aerosolized Mycobacterium tuberculosis that subsequently became inadvertently and transiently malnourished had compromised cell-mediated immunity comparable to that of the rabbits immunosuppressed with dexamethasone. They had significant leukopenia and reduced delayed-type hypersensitivity responses. Malnutrition dampened cell-mediated immunity and would interfere with diagnostic tests that rely on intact CD4 T-cell responses.     

The cytokines NAP-1 (IL-8), MCP-1, IL-1 beta,and GRO in rabbit inflammatory skin lesions produced by the chemical irritant sulfur mustard

Developing and healing dermal inflammatory lesions were produced in rabbits by the topical application of dilute sulfur mustard (SM),⁹ the military vesicant. In tissue sections of such lesions, cells containing the mRNA of important cytokines were identified with in situ hydridization techniques. These cytokines were neutrophil attractant/activation protein-1 (NAP-1 (also called IL-8)), monocyte chemoattractant (activating) protein 1 (MCP-1), interleukin 1 (beta) (IL-1 (beta)), and GRO (a growth factor and chemokine). Mononuclear cells (mainly macrophages and activated fibroblasts) contained the mRNA of all four of these cytokines. A higher percentage of cytokine-producing mononuclear cells (macrophages and activated fibroblasts) was present in lesions at 2 days (their peak size) than at 6 days, when they were almost healed. Granulocytes emigrated from the bloodstream, passed through the lesions, and were the major constituent of the protective crust. This sequence correlated with the distribution of cells able to produce NAP-1: At 2 days and 6 days, the mononuclears that contained messenger RNA for this granulocyte chemoattractant were found mainly in the upper part of the dermis. At 2 days and 6 days, cells containing the mRNA of IL-1, a primary cytokine, were also found predominantly in the upper dermis, i.e., nearest the site of injury. In contrast, mononuclears containing the mRNA of MCP-1 (a monocyte chemoattractant), and the mRNA of GRO (a granulocyte chemoattractant) were more equally distributed throughout the dermis. SM stimulated hair follicle epithelial cells to up-regulate GRO mRNA and, to a lesser degree, NAP-1 mRNA. Apparently, the irritation produced by SM directly or indirectly induces such epithelial cells to manufacture these growth factors. In the rabbit, hair follicles are known to be the main source of new epithelial cells after the covering epithelium has been destroyed. Therefore, GRO is probably a major autocrine-paracrine stimulus for such repair. A brief review of the role of cytokines in dermal inflammation is presented.Abbreviations SM Sulfur mustard: bis(2-chloroethyl)sulfide - GM-CSF Granulocyte-Macrophage Colony Stimulating Factor - GRO A member of the CXC subfamily of chemokines that promotes the multiplication of cells, formerly called melanoma growth stimulating activity (MGSA) - IFN (gamma)-Interferon-gamma - IL-1 Interleukin 1 - IL-8 Interleukin 8 (same as NAP-1)-a CXC chemokine - MCP-1 Monocy te Chemoattractant (Activating) Protein-1-a C-C chemokine - NAP-1 Neutrophil Attractant/Activating Protein-1 (same as IL-8)-a C-X-C chemokine - TGF (beta) Transforming Growth Factor (beta) - TNF (alpha) Tumor Necrosis Factor (alpha) - EDTA Ethylenediamine tetraacetate - DEPC Diethylpyrocarbonate - PBS Phosphate-buffered saline solution - PGE₂ Prostaglandin E₂ - PGI₂ Prostaglandin I₂ (prostacyclin) - SSC Sodium chloride-sodium citrate solution On leave of absence from the Institute for Medical Immunology, Kumamoto University School of Medicine, Kumamoto, Japan.On leave of absence from the Department of Internal Medicine, Oita Medical University, Oita, Japan.