Axial rotation in the lumbar spine and gaping of the zygapophyseal joints

Axial rotation and zygapophyseal joint gaping was studied using 12 human lumbar spines from individuals ranging in age from 14 to 75 years. Using weight and pulley tests and manipulative testing in a torque apparatus, the movement produced by twisting the spine was found not to be pure axial rotation, but rather movement coupled with various combinations of lateral bending and flexion or extension. This motion may not be possible in testing an individual mobile segment. The twisting movements of the spine do not normally produce gaping of the zygapophyseal joints. These joints adapt to the axial rotation by the compliance of their articular cartilages and the movement of fat pads in and out of the joint capsule. Hypermobility appears to be associated with evidence of damage to part of the mobile segment, suggesting that the hypermobility (gaping) at a joint could be due to instability caused by injury.     

The value of a diagnostic setup for full fixed maxillary implant prosthetics.

The concept of prosthesis-directed implant-supported restoration is well accepted. The implementation of this principle for patients requesting full fixed implant-supported maxillary prosthetics has not been thoroughly described. We present a technique for the evaluation and preprosthetic surgical management of patients who are edentulous in the maxilla and wish to have fixed implant-supported crown and bridge prosthetics.     

Autoimmune progesterone dermatitis: absence of contact sensitivity to glucocorticoids, oestrogen and 17-α-OH-progesterone

Autoimmune progesterone dermatitis is a rare condition, characterized by recurrent premenstrual exacerbations of a dermatosis, in which sensitivity to progesterone can be demonstrated. The sensitizing mechanism is unknown. The aim of this study was to test the hypothesis that cross-sensitivity between steroid groups could induce allergy to endogenous progesterone in these patients. 5 patients with autoimmune progesterone dermatitis and 1 with oestrogen-sensitive dermatitis have been patch tested with a corticosteroid series, conjugated oestrogen 1% in petrolatum (pet.), and 17-α-OH-progesterone 2% pet. There were no immediate or delayed reactions at 2 and 4 days to any steroid group. We have therefore been unable to demonstrate steroid cross-sensitivity, or a use for 17-α-OH-progesterone in the investigation of oestrogen - and progesterone-sensitive dermatoses.     

Lupus glomerulonephritis with thrombotic microangiopathy

Well-documented cases of systemic lupus erythematosus (SLE) with thrombotic microangiopathy (TMA) are rare. Renal biopsy in a 25-year-old woman with SLE who was in renal failure demonstrated proliferative lupus glomerulonephritis with arteriolar thrombosis and the arterial intimal changes of TMA. No staining of vessels for immunoglobulins or complement was found by direct immunofluorescence. Fibrillar and flocculent deposits were seen in the widened and rarefied subendothelial space in a small artery and two glomeruli, one of which also contained electron-dense deposits. The vascular findings, which are those of TMA, are distinct from the immune complex vasculopathy of SLE.     

The 'supervirus'? Lessons from IL-4-expressing poxviruses

Members of the Poxviridae family are particularly adept at avoiding the host immune system, encoding a plethora of immunomodulatory proteins that subvert host defense. With their large genome, poxviruses are also useful for studying the effect of exogenous genes on virus-host interactions and immune responses. The insertion of the Th2 cytokine interleukin-4 (IL-4) into several poxviruses significantly increases the efficiency of the recombinant virus as a pathogen by directly inhibiting the development of Th1 immunity, which is crucial for viral clearance. In an age in which the fear of genetically modified weaponized pathogens exists, the understanding of how to make viruses more pathogenic further blurs the distinction between fundamental academic research and bioweapons development. Here, the extent of immune evasion by IL-4-expressing poxviruses will be explored, as will the consequences of this increased pathogenicity on protective immune responses.     

Comparative morphometry of the upper bronchial tree in six mammalian species

The length, diameter, and angle of branching of all airways through the sixth level of branching below the trachea were measured on corrosion casts prepared from the lungs of two animals whose bronchial geometry has not previously been studied, namely the donkey and the rabbit. These measurements and morphometric data for the rat, hamster, dog, and human obtained from other sources were analyzed and compared. The cast prepared from human lungs exhibited an airway geometry that was clearly distinct from that shown by the nonhuman species. The human upper bronchial tree was the most symmetrical with respect to airway diameter and angle of branching. In all species studied, airway length was the most irregular parameter. The reasons for differences in branching geometry are not clearly understood. However, when attempting to determine whether a particular species may be used as a model for man in inhalation toxicology, and in the subsequent interpretation of animal data, an appreciation of differences in airway morphometry is essential.     

Cigarette smoke increases the penetration of asbestos fibers into airway walls.

For study of the penetration of asbestos fibers into airway walls, guinea pigs were given amosite asbestos by intratracheal instillation. Half of the animals were also exposed to cigarette smoke. Animals were sacrificed at 1 week and 1 month, and numbers of fibers in airway walls were counted in histologic sections. In both smoke-exposed and nonexposed groups, numbers of fibers per square millimeter of airway wall increased from 1 week to 1 month in the respiratory bronchioles. At each time period, smoke-exposed animals had significantly higher numbers of fibers in the airway walls, compared with nonexposed animals. It is concluded that 1) continued transport of fibers into interstitial tissues may be the reason that asbestosis can progress after cessation of exposure; 2) cigarette smoke increases the penetration of fibers into airway walls. This effect may play a role in the increased incidence of disease seen in smoking, compared with nonsmoking, asbestos workers.     

Frequency of meiotic trisomy depends on involved chromosome and mode of ascertainment

Although maternal meiotic errors predominate in most studies of nonmosaic trisomy, studies of trisomy ascertained through confined placental mosaicism (CPM) have shown a high rate of somatic errors. However, origin of trisomy of many of the chromosomes involved in CPM has not been evaluated previously in cases ascertained through spontaneous abortions (SAs). Therefore, it was impossible to determine if the relative lack of meiotic errors in trisomy-CPM cases was a characteristic of the specific chromosome involved or due simply to ascertainment through a mosaic state. In the present study, parental and meiotic/somatic stages of origin of trisomy were determined in 89 SAs involving trisomy of chromosomes 2, 4 to 10, 12, 15, 17, and 20. Comparisons were then made to origin of trisomy in cases of confined and generalized trisomy mosaicism. Although somatic errors are generally more common in mosaic cases, this depends on the specific chromosome involved. The results suggest that there are chromosome-specific differences in the relative frequency of somatic chromosome gain or loss and/or the ability of an early somatic loss of one chromosome from a trisomic conceptus to "rescue" the pregnancy. As mean maternal age was less in the somatic than meiotic origin cases (P < 0.01), the age distribution of the study population should also influence the probability of detecting a somatic error. No phenotypic differences were apparent when cases were subdivided based on either parent or stage of origin of the trisomy.