Laryngeal chondroma: a benign process with long-term clinical implications

Chondroma of the laryngeal cartilage is a rare, benign neoplasm which can manifest as a neck mass or, if situated within the airway, as slowly progressive obstruction, hoarseness or dyspnea. The most common location for chondroma is the posterior lamina of the cricoid cartilage; the next most common locations are the thyroid, arytenoid and epiglottic cartilages. Chondroma and low-grade chondrosarcoma are difficult to distinguish from one another histologically. Although chondrosarcoma reportedly recurs, local surgical excision without radical margins and with long-term clinical follow-up is recommended. We report one case of thyroid cartilage chondroma and include a review of radiologic studies and histopathologic analysis results. We also report a second case with severe airway obstruction caused by a large cricoid chondroma. A review of the English language biomedical literature on laryngeal chondroma is included.     

Langerhans cell histiocytosis isolated to the thyroid gland

Isolated Langerhans cell histiocytosis of the thyroid is an extremely rare occurrence, with only one case previously reported. A case of Langerhans cell histiocytosis isolated to the thyroid gland associated with lymphocytic thyroiditis is presented and clinical implications are discussed.     

Evolutionary patterns among measures of aging

Maximum lifespan has been one of the most common aging measures in comparative studies, while the Gompertz model has recently attracted both proponents and critics of its capacity to adequately describe the acceleration of mortality in the oldest age classes. The Gompertz demographic model describes age-dependent mortality rate acceleration and age-independent mortality using the parameters alpha and A, respectively. Evolutionary biologists have predominantly used average longevity in studies of aging. Little is known about the evolutionary relationships of these measures on the microevolutionary time scale. We have simultaneously compared Gompertz parameters, average longevity, and maximum longevity in 50 related populations of Drosophila melanogaster, many of which have been selected for postponed aging. Overall, these populations have differentiated significantly for the A and alpha parameter of the Gompertz equation, as well as average and maximum longevity. These indices of aging appear to measure the same genetic changes in aging. However, in some specific population comparisons, the relationships among these measures are more complex. In a second experiment, environmental manipulation of longevity had substantially different effects from genetic differentiation, with the A parameter accounting for changes in overall mortality. The adequacy of the maximum lifespan and the Gompertz equation as indices of aging in evolutionary studies is discussed.     

Variations in learning reflect individual differences in sensory function and synaptic integration

With the invertebrate Hermissenda as subjects, variability in acquisition of a learned association between light and rotation was correlated with the magnitude of the unconditioned responses elicited by these stimuli. Moreover, learning was facilitated by increasing stimulus intensity. In the isolated nervous system, pairings of light and mechanical stimulation of the animal's vestibular hair cells resulted in an increase in the excitability of B photoreceptors (an in vitro index of learning) that was strongly correlated with the strength of the synaptic interaction between the hair cells and the photoreceptors and weakly correlated with the magnitude of the light response in the photoreceptors. Because these in vitro results are not attributable to motor or motivational variables, they suggest that the efficacy of synaptic integration between sensory systems and sensory transduction is the primary determinant of the variability in learning.     

Autologous stem cell transplantation. From bone marrow to selected blood stem cells: 100 consecutive procedures at a single center

One hundred consecutive autologous stem cell transplants are reported: Non-Hodgkin's lymphoma 51 cases, Hodgkin's disease 27 cases, acute leukaemia 14 cases, multiple myeloma seven cases and chronic myeloid leukaemia one case. Most patients were in their second or later remission. The overall three-year survival for all patients was 60% and the three-year disease-free survival was 50% for lymphoma patients and 30% for acute leukaemia patients. The dominant source of stem cells was bone marrow during 1993, but from 1994 it has been peripheral blood, now totalling 33 cases. There were 12 toxic deaths, all among patients who were heavily treated before bone marrow harvest and transplantation. The patients transplanted with blood stem cells had significantly shorter duration of pancytopenia, and hospital stay, but their disease-free survival was not longer than that of a comparable group of bone marrow transplanted patients. Six patients were transplanted with purified CD34+ cells (selected by avidity column (Ceprate (R)), and had duration of thrombocytopenia and hospital stay similar to the patients transplanted with unmanipulated blood stem cells, but slightly longer duration of neutropenia. We conclude that high-dose therapy with autologous stem cell transplantation in not too heavily pretreated patients is a safe procedure irrespective of the source of stem cells.     

The inter-locus recombinant HLA-B*4601 has high selectivity in peptide binding and functions characteristic of HLA-C

The vast majority of new human HLA class I alleles are formed by conversions between existing alleles of the same locus. A notable exception to this rule is HLA-B*4601 formed by replacement of residues 66-76 of the alpha 1 helix of B*1501 by the homologous segment of Cw*0102. This inter-locus recombination, which brings together characteristic elements of HLA-B and HLA-C structure, is shown here to influence function dramatically. Naturally processed peptides bound by B*4601 are distinct from those of its parental allotypes B*1501 and Cw*0102 and dominated by three high abundance peptides. Such increased peptide selectivity by B*4601 is unique among HLA-A,B,C allotypes. For other aspects of function, presence of the small segment of HLA-C-derived sequence in an otherwise HLA-B framework converts B*4601 to an HLA-C-like molecule. Alloreactive cytotoxic T lymphocytes (CTL), natural killer (NK) cells, and cellular glycosidases all recognize B*4601 as though it were an HLA-C allotype. These unusual properties are those of an allotype which has frequencies as high as 20% in south east Asian populations and is associated with predisposition to autoimmune diseases and nasopharyngeal carcinoma.     

Prospective assessment of pregnancy outcomes after first-trimester exposure to fluconazole

OBJECTIVE: Our purpose was to study prospectively the pregnancy outcome after first-trimester exposure to fluconazole, an effective antifungal agent teratogenic in animals. STUDY DESIGN: We conducted a prospective cohort study of women who contacted three Italian teratogen information services. We compared the pregnancy outcomes of 226 women exposed to fluconazole with that of 452 women exposed to nonteratogenic agents, with use of logistic regression to control for potential confounders. RESULTS: Among the 226 pregnancies exposed to fluconazole there were 22 miscarriages, 1 stillbirth, and 7 infants with congenital anomalies. The prevalence of these outcomes and of neonatal growth parameters and the rate of neonatal complications were similar to those in the reference group. Women in the fluconazole group had a fivefold increased occurrence of induced abortions. CONCLUSIONS: First-trimester exposure to fluconazole does not appear to increase the prevalence of miscarriages, congenital anomalies, and low birth weight.