Epidermal T lymphocytes--ontogeny, features and function.

Conclusions The murine epidermis contains a network of Thy-1⁺ dendritic T cells. These T cells arise from early fetal stem cells and differentiate in the fetal or neonatal thymic or epidermal microenvironment. Their lack of expression of CD5, CD4, and CD8 antigens, as well as their virtually exclusive expression of a CD3/TCR V3/V1 complex, distinguishes DETC from the bulk of peripheral T cells.The early appearance of TCR / cells in ontogeny, the lack of expression of CD4 and CD8 antigens, and the relative paucity of and genes compared to and genes, indicates that / T cells provide a phylogenetically primitive, broadly acting, and poorly discriminating immunologic defense system. In this system, recognition of antigen is not restricted by classical MHC class I and class II antigens, but may occur in the context of relatively nonpolymorphic restricting elements, such as Qa [82], Tla [10] or CD1 [62]. This rather primitive immune system provided by DETC may serve to protect the epidermal integrity. Upon recognition of self proteins released following epidermal injury, DETC may become activated and assist in the removal of altered cells. In this limited fashion, the epidermis may be an independently competent immunologic system. However, the fact that the TCR repertoire of DETC does not allow for the recognition of antigenic peptides in conjunction with MHC moieties excludes the possibility that the diverse immune response elicited by topical contact with foreign antigens is mediated by DETC.Whether this statement also applies to the human epidermis cannot be answered at the present time. Let us consider a few plausible concepts concerning derivation and function of human epidermal T cells. First, one could postulate that in early ontogeny, the human epidermis harbors a small, indigenous population of naive T lymphocytes with monomorphic TCR representing an analogue to murine DETC. These cells could function in a manner similar to that proposed for murine DETC. They may even persist into adult life, so far undetected because they would be outnumbered by immigrating polymorphic T cells from peripheral lymphoid organs. Second, it is conceivable that the human epidermis contains an indigenous population of naive T lymphocytes with a polymorphic TCR repertoire representing a phylogenetically advanced analogue to murine DETC. Although equipped with TCR allowing antigen recognition in the context of MHC, their density is probably too low to make them an effective host defense system against the multitude of environmental antigens presented by Langerhans cells. One could rather assume that they proliferate upon recognition of self antigens occurring in a perturbed epidermis. The autoreactivity of these cells may not necessarily be beneficial. Finally, the fact that the entry of circulating HECA-452⁺ memory cells into the skin is dependent upon the injury-induced ELAM-1 expression by endothelial cells of the dermal microvasculature could indicate that all T cells present in adult human epidermis are recruited upon alteration of the skin. Following this reasoning, the human epidermis should not be regarded as a complete, self-sustaining immunologic organ but rather as a homing site for and a target of lymphocytes antigenically sensitized in peripheral lymphoid organs.     

Reflex increases in heart-rate induced by perfusing the hind leg of the rat with solutions containing lactic acid

The hypothesis that metabolic receptors in skeletal muscle influence heart-rate during exercise was tested by means of a perfused preparation of the rat's hind legs. The isolated leg was connected to the body only by nerve and bone and was perfused with tyrode solution. The humoral changes of exercise were simulated by perfusing with modified tyrode solutions in which concentration of K⁺, osmolality, concentrations of lactic acid, and inorganic phosphate were changed to reflect to those occurring during heavy exercise. Only perfusion with a solution enriched with lactic acid elicited a significant increase in heart-rate. The response disappeared when the nerve supply to the leg was cooled or sectioned. 20–60 s after the start of perfusion with solution of high [lactic acid] heart-rate began to increase reaching a maximum ( ± SE = 20.2 ± 8.2,n = 7) after about 2 min. The effect on heart-rate increased when the venous concentration of lactic acid was increased the range from 3 to 10 mmol/l. In further experiments, we tried to separate the effects of pH and lactate. Heart-rate responses were induced only at low pH and at low pH the extent to which heart-rate changed increased with increases in lactate concentration.     

Assisted reproduction in male cancer survivors: fertility treatment and outcome in 67 couples

BACKGROUND: Many male cancer survivors experience fertility problems due to antineoplastic treatment. We report the fertility outcome in 67 couples referred to assisted reproduction treatment (ART) because of male factor infertility due to cancer. METHODS: This was a retrospective study assessing the following parameters: diagnosis, cancer treatment, type of fertility treatment and type of sperm used, number of pregnancies and pregnancy outcome. RESULTS: Testicular cancer and lymphomas were the most prevalent diagnoses. Adjuvant treatment with chemo- and/or radiation therapy had been given to 90% of the men. Semen was cryopreserved in 82% of the men prior to treatment. Following antineoplastic treatment, 43% of the men had motile spermatozoa in the ejaculate, but 57% were azoospermic. A total of 151 ART cycles were performed [55 intra-uterine insemination (IUI), 82 ICSI and 14 ICSI-frozen embryo replacement (FER)]. The clinical pregnancy rate per cycle was 14.8% after IUI, 38.6% after ICSI and 25% after ICSI-FER. The corresponding delivery rates were 11.1, 30.5 and 21%. Cryopreserved semen was used in 58% of the pregnancies. The delivery rate per cycle was similar after use of fresh or cryopreserved spermatozoa. CONCLUSIONS: Male cancer survivors have a good chance of fathering a child by using either fresh ejaculated sperm or cryopreserved sperm.     

Characterization of a novel breast carcinoma xenograft and cell line derived from a BRCA1 germ-line mutation carrier

A human tumor xenograft (L56Br-X1) was established from a breast cancer axillary lymph node metastasis of a 53-year-old woman with a BRCA1 germ-line nonsense mutation (1806C>T; Q563X), and a cell line (L56Br-C1) was subsequently derived from the xenograft. The xenograft carries only the mutant BRCA1 allele and expresses mutant BRCA1 mRNA but no BRCA1 protein as determined by immunoprecipitation or Western blotting. The primary tumor, lymph node metastasis, and xenograft were hypodiploid by DNA flow cytometry, whereas the cell line displayed an aneuploidy apparently developed via polyploidization. Cytogenetic analysis, spectral karyotyping, and comparative genomic hybridization of the cell line revealed a highly complex karyotype with numerous unbalanced translocations. The xenograft and cell line had retained a somatic TP53 missense mutation (S215I) originating from the primary tumors, as well as a lack of immunohistochemically detectable expression of steroid hormone receptors, epidermal growth factor receptor, human epidermal growth factor receptor 2 (HER-2), and keratin 8. Global gene expression analysis by cDNA microarrays supported a correlation between the expression profiles of the primary tumor, lymph node metastasis, xenograft, and cell line. We conclude that L56Br-X1 and L56Br-C1 are useful model systems for studies of the pathogenesis and new therapeutic modalities of BRCA1-induced human breast cancer.     

Quantitative expansion of structural genomic alterations in the spectrum of neuroendocrine lung carcinomas

The pathogenesis and interrelationships of neuroendocrine lung carcinomas are not well understood. Tissue macro-arrays prepared from surgical resection specimens from 35 patients with typical carcinoid (TC), six with atypical carcinoid (AC), 13 with large cell neuroendocrine carcinoma (LCNEC), and 15 with small cell lung carcinoma (SCLC) were investigated by fluorescence in situ hybridization (FISH) and immunohistochemistry. Hybridizations with locus-specific DNA probes demonstrated a high incidence of deletion for the tumour suppressor genes p53 and retinoblastoma (Rb), and for the oncogene cyclin D1, comparable in all carcinoma types. Similarly, an increase of DNA copy number for the Her-2/neu and c-myc oncogenes was noted in all neoplasms. A more detailed quantitative analysis of the results, however, demonstrated increasing numbers of cells harbouring these genomic alterations, from low-grade TC to highly malignant SCLC, with the exception of cyclin D1 deletion. Mutations of the p53 and Rb genes, as assayed by immunohistochemical studies, were observed at high incidence in high-grade carcinomas, compared with a low incidence in the low-grade carcinomas. Conversely, in all carcinoma types, neither membrane-bound Her-2/neu nor nuclear cyclin D1 was detected. It is concluded that structural genomic alterations are frequent in neuroendocrine lung carcinomas and that their occurrence may be underestimated by immunohistochemical studies alone. The quantitative expansion of the Rb, p53, c-myc, and Her-2/neu alterations towards high-grade carcinomas suggests common pathogenetic mechanisms in the spectrum of these neoplasms.     

Vasopressin release and firing of supraoptic neurosecretory neurones during drinking in the dehydrated monkey

A close relationship exists between drinking and the release of vasopressin, the two main factors responsible for the maintenance of body water content. Whereas the participation of peripheral factors, such as oropharyngeal stimulation, seems obvious in the metering of fluid intake and in thirst satiation, very little is known about their influence on vasopressin release. In the present experiments, the influence of drinking on vasopressin release was studied using both biochemical and electrophysiological approaches.In one group of monkeys made thirsty by water deprivation, the subsequent drinking of water during a 5–8 min induced: i) a short-term response, consisting of an abrupt fall in plasma vasopressin concentration which was independent of osmolality, occurred at the time of drinking and was partly reversed after the cessation of drinking, and ii) a longer lasting response, consisting of a slow diminution of plasma vasopressin concentration as the intestinal absorption of water progressed. In another group of thirsty monkeys, extracellular recordings were made during drinking from cells which were identified as neurosecretory neurones of the supraoptic nucleus, a number of them being considered vasopressin secreting on the basis of their phasic pattern of firing. Their firing decreased considerably during the periods of water intake and recovered to control levels immediately after-wards.The decrease in vasopressin release at the onset of water intake, the diminution in the firing rate of the neurones, the short latency and the reversibility of these events after cessation of drinking, suggest that a reflex inhibition of vasopressin-secreting neurones occurs which is probably induced by peripheral stimuli and most likely via oropharyngeal or other visceral receptors. It is postulated that this reflex inhibition of vasopressin release may participate in some active manner in the anticipatory mechanisms of thirst satiation.     

Resistance exercise training and the orthostatic response

Resistance exercise has been suggested to increase blood volume, increase the sensitivity of the carotid baroreceptor cardiac reflex response (BARO), and decrease leg compliance, all factors that are expected to improve orthostatic tolerance. To further test these hypotheses, cardiovascular responses to standing and to pre-syncopal limited lower body negative pressure (LBNP) were measured in two groups of sedentary men before and after a 12-week period of either exercise (n = 10) or no exercise (control, n = 9). Resistance exercise training consisted of nine isotonic exercises, four sets of each, 3 days per week, stressing all major muscle groups. After exercise training, leg muscle volumes increased (P?P = 0.00) by 2.0 (0.5)?kg, leg compliance and BARO were not significantly altered, and the maximal LBNP tolerated without pre-syncope was not significantly different. Supine resting heart rate was reduced (P = 0.03) without attenuating the heart rate or blood pressure responses during the stand test or LBNP. Also, blood volume (¹²⁵I and ⁵¹Cr) and red cell mass were increased (P?相似文献   

Sleep related breathing disorders in older men: A search for underlying mechanisms

—The incidence of sleep-related breathing disorders (SRBDs) associated with hemoglobin desaturation was determined by nocturnal polygraphic evaluations in 26 healthy men, aged 55–70 years. Sixteen subjects (62%) had abnormal rates of at least 12 episodes per hour of sleep: 8 had occlusive, and 8 had central apnea or hypopnea. During waking ten of 16 SRBD subjects and only one subject without SRBDs exhibited either an elevated nasopharyngeal airway resistance (n=4) or a reduced ventilatory response to hypercapnia (n=4) and/or hypoxia (n=3). However, these abnormalities were not related to the type or severity of SRBDs, and 6 subjects with SRBDs demonstrated no respiratory defect. We conclude that SRBDs have a very high incidence in older males and are not usually secondary to pulmonary cardiac, neurological, or behavioral disorders. Additionally, we hypothesize that abnormalities in ventilatory control or upper airway resistance contribute to SRBDs, but depression of brain stem reticular formation activity during sleep plays a primary role in these disorders. Factors related to both aging and SRBDs are reviewed. These include reduced chemoreceptor responses, altered steroid hormone metabolism, and use and metabolism of hypnotic drugs and alcohol.