Two separable T cell receptor signals reconstitute positive selection of CD4 lineage T cells in vivo

Positive selection is an obligatory step during intrathymic T cell differentiation. It is associated with rescue of short-lived, self major histocompatibility complex (MHC)-restricted thymocytes from programmed cell death, CD4/CD8 T cell lineage commitment, and induction of lineage-specific differentiation programs. T cell receptor (TCR) signaling during positive selection can be closely mimicked by targeting TCR on immature thymocytes to cortical epithelial cells in situ via hybrid antibodies. We show that selection of CD4 T cell lineage cells in mice deficient for MHC class I and MHC class II expression can be reconstituted in vivo by two separable T cell receptor signaling steps, whereas a single TCR signal leads only to induction of short-lived CD4+CD8lo intermediates. These intermediates remain susceptible to a second TCR signal for 12-48 h providing an estimate for the duration of positive selection in situ. While both TCR signals induce differentiation steps, only the second one confers long-term survival on immature thymocytes. In further support of the two-step model of positive selection we provide evidence that CD4 T cell lineage cells rescued by a single hybrid antibody pulse in MHC class II-deficient mice are pre-selected by MHC class I.     

Improving the processes of care and outcomes in obstetrics/gynecology

BACKGROUND: The obstetrics/gynecology department of York Hospital (York Health System, York, Pennsylvania) initiated a program to improve the processes of care and control costs for common women's and newborns' health care services. Twelve clinical policies were established between June 1993 and February 1995. CONDUCTING THE QUALITY IMPROVEMENT (QI) PROJECTS: Using the plan-do-check-act (PDCA) improvement cycle method, the QI group established clinical pathways for high-volume conditions or procedures known to have low rates of complications and clinical guidelines for those conditions or procedures not requiring coordinated efforts of a group of health care professionals. EXAMPLE--PYELONEPHRITIS IN PREGNANCY: The literature had indicated that the prevalence of pyelonephritis can be decreased by identifying and treating asymptomatic bacteriuria early in prenatal care. After the validity of the clinical policy was demonstrated in the resident service, the policy was extended to all private obstetric practices. Dissemination of the finding that most of the admissions for pyelonephritis were for referred patients (for whom we had no control over prenatal care) or for patients referred by private physicians who were not yet following the guidelines quickly led to complete compliance by our obstetricians and other health care providers referring patients to the York Health System. RESULTS: The 12 clinical policies resulted in the elimination of 113 admissions and 5,595 inpatient days and in the reduction of the cost of patient care by $1,306,214 for the years 1994-1995 and 1995-1996 combined, without apparent adverse effects on patient health. CONCLUSION: A voluntary clinical policies program can change the culture of a department and lead to cost-effectiveness and better quality of patient care.     

Dogs infected with a human granulocytotropic Ehrlichia spp. (Rickettsiales: Ehrlichieae)

In contrast to the anticipation that in sepsis granulocyte colony-stimulating factor (G-CSF) would overactivate the nonspecific immune system by recruiting and priming leukocytes with consequent aggravation of inflammatory tissue lesions, recombinant (r) G-CSF pretreatment was protective in various experimental non-neutropenic models of inflammation. The mechanisms of protection, however, are not fully understood. Using intravital fluorescence microscopy, we show that rG-CSF enhances leukocyte endothelial cell interaction within the microvasculature of normal rat livers, whereas rG-CSF pretreatment of animals exposed to lipopolysaccharide (LPS) attenuates the LPS-induced leukocytic response, including stasis in sinusoids as well as rolling and adherence in postsinusoidal venules with subsequent tissue infiltration. Moreover, rG-CSF, which did not affect Kupffer cell activity in normal rat livers, reduced the immediate activation of Kupffer cells on LPS exposure, as indicated in vivo by the delayed adherence/phagocytosis of intra-arterially administered latex particles associated with attenuation of proinflammatory cytokine release (tumor necrosis factor alpha and interleukin-6). Finally, rG-CSF reduced LPS-induced nutritive perfusion failure and hepatocellular excretory dysfunction. This study provides evidence for a distinct, possibly tumor necrosis factor alpha-dependent modulation of LPS-induced cellular response within the liver by rG-CSF, thereby achieving protection against microcirculatory perfusion failure and hepatic dysfunction.     

Immediate sexual rehabilitation by simultaneous placement of penile prosthesis in patients undergoing radical prostatectomy: initial results in 50 patients

Hypotonicity-induced anion permeability changes were investigated but not detected in immortalised (RBE4) rat brain endothelial cells using iodide efflux measurements. Large, rapid increases were however observed in primary cultured cells. Both cell types were reinvestigated following culture in a common growth factor-depleted medium. Responses were still undetectable in the immortalised RBE4 cells. Reduced responses were observed in the primary cultured cells that also showed altered morphology and decreased activity of another transporter, P-glycoprotein. Thus both immortalisation and different culture conditions may alter functional expression in these cells of transporters involved in hypotonicity-induced anion permeability changes.     

Infection prophylaxis in complex limb trauma through immediate definitive reconstruction via a free tissue transfer

Levels of specific IgE antibodies to three kinds of venom (honeybee, wasp and yellow jacket) were followed up for two years in five male pest control operators (age: 24 to 50 years) with Hymenoptera sting within the latest six months. At the first examination, all subjects had a positive reaction for venom-specific IgE but their levels were varied in the range from class 2 to 5 (0.70 approximately 99.9 UA/ml), and a positive reaction was observed in the case of unoffending Hymenoptera. A subject who was re-stung during the two-year follow-up period showed increase in all of the venom-specific IgE levels. Of four subjects without re-stung during the two years, three subjects had a logarithmic decrease in all the specific IgE levels time-dependently, but one subject with a high total serum IgE level showed an increase and decrease alternately in the specific IgE The total serum IgE level may be a factor which influences the change in the venom-specific IgE level. In the four subjects without a high total serum IgE level, the biological half-life of venom-specific IgE was estimated to be 6 to 12 months based on the decreased level during the follow-up period.     

Cutting seton for anal fistulas: high risk of minor control defects

PURPOSE: Long-term results of cutting seton in the treatment of anal fistulas were studied. METHODS: Of the 44 patients with anal fistulas, mainly of the high variety, managed with this method, 35 (25 men) attended a clinical and manometric follow-up examination on average 70 (range, 28-184) months after operation. Fistula distribution was high transsphincteric (25), low transsphincteric (5), extrasphincteric (3), and suprasphincteric (2). The seton was tightened at one-week to two-week intervals to achieve gradual sphincter division. RESULTS: Time required to achieve complete fistula healing ranged from 37 to 557 (mean, 151) days. Two (6 percent) of the 35 patients re-examined had recurrence of fistula and 22 (63 percent) reported symptoms of minor impairment in anal control, which in four patients had existed already before operation. Anal resting pressures were similar for defective and normal control, but other manometric variables were inferior in incontinence, although total squeeze pressure only showed statistically significant difference from normal continence (P = 0.0345). Incontinence was likely associated with hard and gutter-shaped operation scars in the anal canal, but the difference from normal continence was not statistically significant. CONCLUSION: Cutting seton yields fairly good results in regard to cure of fistula, but the risk of anal incontinence, despite its minor degree, seems to be too high to recommend its routine use for all high fistulas. The suprasphincteric fistulas and some extrasphincteric fistulas are difficult to treat otherwise, but especially for high transsphincteric fistulas, other methods of treatment (preferably those in which sphincter division can be avoided and the risk of anal canal deformity and incontinence are minimized) are advocated.     

Circulating kallikreins during sodium chloride infusion in normal and hypertensive humans

Early radical cystectomy for a high-grade tumor invading the lamina propria (T1) remains controversial. In 1997, we cannot identify accurately which of these high-risk tumors will progress to muscle-invasive disease and metastases. In the near future, urologists may be able to use the presence of genetic alterations, such as p53 mutations, to help make therapeutic decisions. Previous reports on superficial bladder cancer treated with intravesical bacillus Calmette-Guérin immunotherapy have demonstrated a decrease in recurrence and progression. Unfortunately, there is no reliable method to predict which patients with a high-grade T1 tumor will fail to respond to intravesical therapy. Failure of intravesical therapy to control these aggressive tumors is associated with a significant rate of pathological upstaging and metastases. Radical cystectomy will cure a high percentage of these T1 tumors with acceptable morbidity and low mortality. In an era of nerve-sparing cystectomy and orthotopic neobladder reconstruction, early radical cystectomy is an alternative that should be discussed with the patient before instituting intravesical therapy.     

Angiogenesis promoted by vascular endothelial growth factor: regulation through alpha1beta1 and alpha2beta1 integrins

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a cytokine of central importance for the angiogenesis associated with cancers and other pathologies. Because angiogenesis often involves endothelial cell (EC) migration and proliferation within a collagen-rich extracellular matrix, we investigated the possibility that VEGF promotes neovascularization through regulation of collagen receptor expression. VEGF induced a 5- to 7-fold increase in dermal microvascular EC surface protein expression of two collagen receptors-the alpha1beta1 and alpha2beta1 integrins-through induction of mRNAs encoding the alpha1 and alpha2 subunits. In contrast, VEGF did not induce increased expression of the alpha3beta1 integrin, which also has been implicated in collagen binding. Integrin alpha1-blocking and alpha2-blocking antibodies (Ab) each partially inhibited attachment of microvascular EC to collagen I, and alpha1-blocking Ab also inhibited attachment to collagen IV and laminin-1. Induction of alpha1beta1 and alpha2beta1 expression by VEGF promoted cell spreading on collagen I gels which was abolished by a combination of alpha1-blocking and alpha2-blocking Abs. In vivo, a combination of alpha1-blocking and alpha2-blocking Abs markedly inhibited VEGF-driven angiogenesis; average cross-sectional area of individual new blood vessels was reduced 90% and average total new vascular area was reduced 82% without detectable effects on the pre-existing vasculature. These data indicate that induction of alpha1beta1 and alpha2beta1 expression by EC is an important mechanism by which VEGF promotes angiogenesis and that alpha1beta1 and alpha2beta1 antagonists may prove effective in inhibiting VEGF-driven angiogenesis in cancers and other important pathologies.     

Influence of Head Geometry on Bolted Joint Behavior

Numerical models of single-fastener bolted lap joints are developed in which the effect of the head angle and height on joint elongation are studied for three fastener sizes, three panel materials, and several panel thicknesses. Baseline 100° bolt-head angle numerical models are calibrated and validated with experimental data. These baseline models are then modified to predict the load-elongation behavior of lap joints with five different head angles and four different head heights. The numerical predictions are summarized in graphical form. The results show that the fastener head height has a much greater influence on joint-slip resistance than does the angle, with the shallower heads providing the greatest resistance to joint elongation under load.