Pollination context alters female advantage in gynodioecious Silene vulgaris.

Gynodioecy, the co-occurrence of females and hermaphrodites, is arguably the most common angiosperm gender polymorphism in many florae. Females' ability to invade and persist among hermaphrodites depends, in part, on pollinators providing adequate pollination to females. We directly measured diurnal and nocturnal pollinators' contributions to female and hermaphrodite seed production in artificial populations of gynodioecious Silene vulgaris by experimentally restricting pollinator access. We found that female relative seed production in this system depended strongly on pollination context: females produced more than twice as many seeds as hermaphrodites in the context of abundant, nectar-collecting moths. Conversely, females showed no seed production advantage in the context of pollen-collecting syrphid flies and bees due to acutely hermaphrodite-biased visitation. We infer that variation in pollinator type, behaviour and abundance may be important for achieving the female relative fitness thresholds necessary for the maintenance of gynodioecy. Generally, our study illustrates how pollinator-mediated mechanisms may influence the evolution of breeding systems and associated suites of floral traits. Segments of a pollinator community may facilitate gynodioecy by selecting for plant characteristics that increase the attractiveness of both sexes to pollinators, such as nectar rewards. Conversely, discriminating visitors in search of pollen may restrict gynodioecy in associated plant lineages by reducing male steriles' fitness below threshold levels.

Design of T-cell receptor libraries with diverse binding properties to examine adoptive T-cell responses.

Adoptive T-cell therapies have shown significant promise in the treatment of cancer and viral diseases. One approach, which introduces antigen-specific T-cell receptors (TCRs) into ex vivo activated T cells, is designed to overcome central tolerance mechanisms that prevent responses by endogenous T-cell repertoires. Studies have suggested that use of higher-affinity TCRs against class I major histocompatibility complex antigens could drive the activity of both CD4(+) and CD8(+) T cells, but the rules that govern the TCR binding optimal for in vivo activity are unknown. Here, we describe a high-throughput platform of 'reverse biochemistry' whereby a library of TCRs with a wide range of binding properties to the same antigen is introduced into T cells and adoptively transferred into mice with antigen-positive tumors. Extraction of RNA from tumor-infiltrating lymphocytes (TILs) or lymphoid organs allowed high-throughput sequencing to determine which TCRs were selected in vivo. The results showed that CD8(+) T cells expressing the highest-affinity TCR variants were deleted in both the TIL population and in peripheral lymphoid tissues. In contrast, these same high-affinity TCR variants were preferentially expressed within CD4(+) T cells in the tumor, suggesting they had a role in antigen-specific tumor control. The findings thus revealed that the affinity of the transduced TCRs controlled the survival and tumor infiltration of the transferred T cells. Accordingly, the TCR library strategy enables rapid assessment of TCR-binding properties that promote peripheral T-cell survival and tumor elimination.

Single-chain VαVß T-cell receptors function without mispairing with endogenous TCR chains.

Transduction of exogenous T-cell receptor (TCR) genes into patients' activated peripheral blood T cells is a potent strategy to generate large numbers of specific T cells for adoptive therapy of cancer and viral diseases. However, the remarkable clinical promise of this powerful approach is still being overshadowed by a serious potential consequence: mispairing of the exogenous TCR chains with endogenous TCR chains. These 'mixed' heterodimers can generate new specificities that result in graft-versus-host reactions. Engineering TCR constant regions of the exogenous chains with a cysteine promotes proper pairing and reduces the mispairing, but, as we show here, does not eliminate the formation of mixed heterodimers. By contrast, deletion of the constant regions, through use of a stabilized Vα/Vß single-chain TCR (scTv), avoided mispairing completely. By linking a high-affinity scTv to intracellular signaling domains, such as Lck and CD28, the scTv was capable of activating functional T-cell responses in the absence of either the CD3 subunits or the co-receptors, and circumvented mispairing with endogenous TCRs. Such transduced T cells can respond to the targeted antigen independent of CD3 subunits via the introduced scTv, without the transduced T cells acquiring any new undefined and potentially dangerous specificities.

Neurofilaments are nonessential to the pathogenesis of toxicant-induced axonal degeneration.

Axonal neurofilament (NF) accumulations occur before development of symptoms and before other pathological changes among idiopathic neurodegenerative diseases and toxic neuropathies, suggesting a cause-effect relationship. The dependence of symptoms and axonal degeneration on neurofilament accumulation has been tested here in a transgenic mouse model (Eyer and Peterson, 1994) lacking axonal NFs and using two prototypic toxicant models. Chronic acrylamide (ACR) or 2,5-hexanedione exposure resulted in progressive and cumulative increases in sensorimotor deficits. Neurobehavioral tests demonstrated similar expression of neurotoxicity in transgenic (T) mice and their nontransgenic (NT) littermates (containing normal numbers of axonal NFs). Axonal lesions were frequently observed after exposure to either toxicant. Quantitation of ACR-induced lesions demonstrated the distal location of pathology and equal susceptibility of T and NT axons. We conclude that axonal NFs have no effect on neurotoxicity and the pattern of pathology in these mammalian toxic neuropathies. These results also suggest that the role of neurofilament accumulation in the pathogenesis of neurodegenerative diseases requires careful evaluation.

Stress and depression: a test of the buffering model of social support.

The buffering model of social support states that effective social support networks lessen the adverse psychological consequences of stress. Among a large community sample (N = 1,000) of Los Angeles County adults interviewed in 1979, life-event losses and perceived strain were positively related to depressive symptomatology, while close relationships and perceived support were negatively related to these symptoms. In all models tested, these effects were found to be direct effects, not interaction effects as predicted by the buffering model. The effects of stress on depressive symptomatology were similar among those with low and high levels of social support. Social support, instead of merely protecting an individual against the negative impact of stress, may itself be important in ameliorating depressive symptoms. Moreover, assuming that lack of perceived or actual social support is not just a manifestation of depression itself, our findings support the corollary that the lack of social support contributes to the creation of depressive symptoms.

Development of malabsorption and nutritional complications in simian immunodeficiency virus-infected rhesus macaques.

OBJECTIVE: To assess the development and cause of malabsorption in rhesus macaques following experimental simian immunodeficiency virus (SIV) infection and to evaluate its impact on nutritional status. DESIGN: Clinical malabsorption tests and serial jejunal aspirates and biopsies were obtained from nine SIV-infected and three uninfected animals prior to infection and at 1, 2, 4, 8, 12, 24, 40 and 52 weeks postinoculation. METHODS: Malabsorption was measured by sucrose breath hydrogen (H2) analysis and blood assay of D-xylose. Digestive enzyme activity was determined in jejunal mucosal homogenates. Bacterial and protozoal flora were determined in jejunal aspirates. Nutritional assessment was evaluated using specific blood micronutrient values. Cellular targets of SIV in the jejunum were determined by combined in situ hybridization and immunohistochemistry. RESULTS: Eight out of nine SIV-infected monkeys, including asymptomatic animals, exhibited malabsorption by either increased breath H2 and/or decreased blood D-xylose. All animals that died of AIDS had diarrhea, D-xylose malabsorption and decreased sucrase activity. Significant changes in nutritional status were associated with malabsorption. Bacterial overgrowth was not considered to be a cause of malabsorption. Histopathological biopsy findings included dilated villus lacteals, excessive cellular debris, lymphoplasmocytic infiltrates and cytoplasmic vacuoles in crypt epithelial cells. SIV-infected T cells and macrophages were detected as early as 1 week postinoculation. CONCLUSIONS: SIV-associated malabsorption can occur prior to clinical complications of disease. Severe intestinal complications are associated with malabsorption and malnutrition in the terminal stages of AIDS. The high proportion of macaques experiencing malabsorption without detectable pathogens, suggests an enteropathogenic role for SIV.

Sex dimorphisms in the cognitive-enhancing action of the Alzheimer's drug donepezil in aged Rhesus monkeys.

Brain acetylcholinesterase has been targeted for the development of novel treatments for memory deficits associated with Alzheimer's disease (AD) and other neurodegenerative disorders. The long-acting AChE inhibitor donepezil (Aricept) is used to improve memory and other aspects of cognition in AD patients. Because donepezil and other cholinesterase inhibitors are effective in a restricted population of AD patients, this study was to designed to determine whether aged females monkeys receive the same level of benefit to the mnemonic action of donepezil as do males. In this study, six male and six female rhesus monkeys (>20 years) who were proficient in the performance of a delayed matching-to-sample task each received an ascending series of four doses of donepezil (0.01-0.1 mg/kg) over 5 weeks. As a group, male subjects exhibited improvement in task accuracy across the three highest doses, with the maximum effect occurring after the 0.025 mg/kg dose. However, the females exhibited increased task accuracy only after the highest dose. When data were combined for sessions run 10 min after drug administration and for sessions run 24 h later (in the absence of drug), improvements in task accuracy were greater on average for males. Most of this difference was attributed to the fact that task accuracy by females actually declined during sessions run after the two lowest doses of donepezil. When task performance after donepezil was determined as the individualized Best Dose, as a group, males responded maximally to less than half the dose that was maximal for females. These findings support the concept that aged males and females respond differently to this class of agents, perhaps representing fundamental sex-related differences in memory processing, or in the manner that age affects these processes.

Protractive effects of chronic treatment with an acutely sub-toxic regimen of diisopropylflurophosphate on the expression of cholinergic receptor densities in rats.

Individuals chronically exposed to low levels of organophosphate insecticides may present with subtle impairments in cognition. In addition, low level diisopropylflurophosphate (DFP) exposure (0.25 mg/kg per day for 2 weeks) in rats resulted in protracted working memory impairment [29]. The current studies attempt to show a temporal relationship between the DFP-induced impairment in performance of a spatial memory task and the protracted decrease in the expression of cholinergic receptors and acetylcholinesterase in specific brain regions. Cholinergic receptors labeled with the ligands [(3)H]epibatidine and [(3)H]AFDX-384 were affected to a much greater extent and for a longer period of time than were both acetylcholinesterase activities and cholinergic receptors labeled with [(3)H]QNB. Pre-testing administration of nicotine was shown to completely reverse this DFP-induced impairment in memory-related task performance. Additionally, prophylaxis with pyridostigmine bromide (PB) caused DFP-treated animals to exhibit near normal levels of memory-related task performance. These results are consistent with the development of a protracted phase of learning impairment to sub-acute DFP exposure, which may involve the loss of hippocampal nicotinic receptors, and may be prevented or reversed by PB or nicotine, respectively.

Neurofilaments are non-essential elements of toxicant-induced reductions in fast axonal transport: pulse labeling in CNS neurons.

Acrylamide (ACR) and g-diketones (g-DK) produce distal sensory-motor neuropathy in a variety of species, including humans. The specific molecular site and mechanism of toxicant action leading to specific morphological and behavioral abnormalities requires definition. The relative roles of fast anterograde axonal transport and neurofilaments (NF) are investigated using optic nerves of mice, with and without axonal neurofilaments. Segmental analysis, following pulse labeling with 3H-leucine into the vitreous body, was used to detect changes in fast anterograde transport in the optic nerve and tract. Single injections of ACR significantly reduced the quantity of radiolabeled proteins transported in both transgenic (lacking NF) and non-transgenic (containing NF) mice by 68.4% and 46.2%, respectively. Similarly, single injections of 2,5-hexanedione (2,5-HD) reduced the quantity of radiolabeled transport in transgenic and non-transgenic mice by 55.2% and 47.1%, respectively. Equimolar doses of propionamide and 3,4-hexanedione (non-neurotoxic analogues of ACR and 2,5-HD, respectively) produced no changes in the quantity or apparent rate of optic nerve transport. Additionally, no differences in quantity or apparent rate of transport between transgenic and non-transgenic animals were observed under control or experimental conditions. Therefore, ACR and 2,5-HD reduce the quantity of fast anterograde axonal transport in mouse CNS axons in a comparable amount to previously reported reductions in rat PNS axons. The absence of axonal neurofilaments had no effect on normal fast transport. Furthermore, the presence or absence of neurofilaments did not alter the effect of these toxicants on fast axonal transport. We conclude that toxicant-induced reductions in fast axonal transport are unrelated to ACR and g-diketone effects on NF or their accumulation.

Single-stage reconstruction of mandibular and soft tissue defects using a free osteocutaneous groin flap.

Microvascular reconstruction of the mandible and soft tissues using the composite groin flap is ideal in selected patients. No other available bone so closely approximates the mandible in both thickness and curvature as does the iliac crest. The soft tissues are available for reconstruction and may allow the surgeon to avoid a second flap, except in cases where both lining and cover are needed. The deep circumflex artery is of generous size, usually 2 to 2.5 mm in diameter, allowing greater reliability in the microvascular anastomoses. The flap has a fairly long vascular predicle, 6 to 8 cm. The ability of this flap to withstand irradiation and infection because of its blood supply permits early institution of postoperative radiotherapy and prevents bone loss due to small intraoral wound dehisicence or total flap loss. Although the donor site requires extensive dissection, it can be closed primarily, eliminating the need for skin grafts or other flaps. As further experience is gained with this flap, both the functional and cosmetic results should be improved. In patients undergoing resection of the remaining portion of the mandible, the symphysis or the anterior portion of the mandible, a procedure of this type should be done primarily to prevent deformity and to minimize disability for the patient.

Assessment of posterior cruciate ligament graft performance using robotic technology.

We used the information on in situ forces provided by robotics to compare two methods of posterior cruciate ligament graft fixation. Twenty porcine knees were studied using robotic technology to determine and repeat intact, deficient, and reconstructed knee motion under 110 N of posterior tibial loading at 30 degrees, 60 degrees, and 90 degrees of knee flexion. Reconstruction was performed using a bone-patellar tendon-bone graft with the distal end of the graft placed in the posterolateral aspect of the posterior cruciate ligament tibial insertion. Specimens were separated into two groups based on the femoral fixation site: the proximal or anterior aspect of the femoral insertion. Repetition of knee motion allowed measurement of the force in the intact posterior cruciate ligament and graft using the principle of superposition. The forces in the graft and the intact ligament provided additional information to evaluate graft performance. Force in the intact posterior cruciate ligament was significantly greater at 90 degrees than at 30 degrees and 60 degrees of knee flexion. The forces in both graft types were significantly lower than those of the posterior cruciate ligament, but the force in the anteriorly placed graft was significantly greater at 90 degrees than at 30 degrees and 60 degrees of knee flexion, similar to the intact posterior cruciate ligament. Thus, the anteriorly placed graft had a more physiologic increase in tension with knee flexion, when the joint provided less restraint.

Information processing and estimation of short time intervals.

Duration estimates were assessed by the method of reproduction with filled reproduction intervals. Mental arithmetic, reading and mirror-image drawing were used in pairs as initial and/or reproduction tasks. All nine possible pairs of tasks were used in a 9 X 5 X 5 mixed design with five Ss per task pair and five interruption intervals for each initial task. Results indicated that, when arithmetic was used as the initial task, Ss underestimated the duration of the initial interval. When arithmetic was used as the reproduction task, Ss overestimated the duration of the initial interval. A significant correlation was obtained between arithmetic outputs and the lengths of the duration estimates. Results are interpreted as supportive of Burnside's (1971) interpretation of Ornstein's (1969) storage-size hypothesis.

Annoyance response of nonsmokers to cigarette smoke.

In three experiments, nonsmoking subjects rated their annoyance by task environments while either exposed or not exposed to ambient tobacco smoke. In Exps. 1 and 2 subjects rated annoyance with the environment while exposed to three intensities of noise, and in Exp. 3 subjects rated annoyance while performing multiplication problems under conditions of high and low task motivation. The source of the ambient smoke in Exp. 1 was a smoke pump. For Exps. 2 and 3, the source of the smoke was confederate subjects. No differences in annoyance were obtained in Exps. 1 and 2 as a function of exposure to smoke. Exp. 3 showed that nonsmokers' annoyance to a task environment is dependent upon task motivation and exposure to ambient smoke. In Exp. 3 nonsmokers exposed to smoke were more annoyed than those not exposed under low motivating conditions. When nonsmokers were highly motivated in the task environment those exposed to smoke were significantly less annoyed than those not exposed.

Carbamazepine hypersensitivity reaction.

Carbamazepine is an anticonvulsant that is being used more frequently in the treatment of various psychiatric disorders. The drug has been associated with serious adverse reactions that appear to have an immunological pathogenesis. A case report describing a patient suffering an adverse reaction to carbamazepine is presented, to illustrate the various body systems typically affected in the apparent hypersensitivity reaction. The importance of laboratory and patient monitoring during the initial 3 months of carbamazepine therapy is reinforced.

Racial/ethnic differences in access to health care: further comments on the use-disability ratio.

Indicators of access to health care generally fall into one of two broad groups. The first group of indicators focuses on factors responsible for differential rates of use and often are assessed through reports of patient satisfaction. The second group of indicators focuses more specifically on actual rates of use, and therefore represents a more objective measure of access. One of the most widely used objective indicators of access is the use-disability ratio. This article illustrates some problems in using this ratio in health services research and some strategies one might adopt to minimize these problems. The data reported below were obtained from an analysis of racial/ethnic differences in use of services that was conducted as part of the 1979 Los Angeles Health Survey (N = 1003). Our findings suggest that 1) blacks had greater access to health care than either white/Anglos or Hispanics, particularly for respiratory and musculo-skeletal problems, and 2) the use-disability ratio should be used cautiously, since it is sensitive to subgroup differences in the chronicity and cause of the disability

Sex differences in central cholinergic and angiotensinergic control of vasopressin release.

In conscious, unrestrained rats, the intracerebroventricular injection of the cholinergic agonist, carbachol, or angiotensin II resulted in the transient stimulation of vasopressin secretion, elevation of mean arterial blood pressure, and reduction of heart rate. After the injection of carbachol (25 ng) into a lateral cerebral ventricle, the plasma vasopressin concentration in male rats was increased to twice that of female rats in each phase of the estrous cycle; mean arterial blood pressure was elevated more in males than females, whereas heart rate fell to the same extent in both sexes. In contrast, the increase in the plasma vasopressin concentration of males after the injection of angiotensin II (20 ng) was one-half that of females, and the hypertensive and bradycardic responses were similar in both sexes. Phase of the female estrous cycle had no effect on the responses to either agent. These findings indicate that central cholinergic and angiotensinergic mechanisms controlling vasopressin release are influenced differently by gender. The role of the gonadal steroid hormones in these mechanisms remains to be determined.

T-cell activation by soluble MHC oligomers can be described by a two-parameter binding model.

T-cell activation is essential for initiation and control of immune system function. T cells are activated by interaction of cell-surface antigen receptors with major histocompatibility complex (MHC) proteins on the surface of other cells. Studies using soluble oligomers of MHC-peptide complexes and other types of receptor cross-linking agents have supported an activation mechanism that involves T cell receptor clustering. Receptor clustering induced by incubation of T cells with MHC-peptide oligomers leads to the induction of T-cell activation processes, including downregulation of engaged receptors and upregulation of the cell-surface proteins CD69 and CD25. Dose-response curves for these T-cell activation markers are bell-shaped, with different maxima and midpoints, depending on the valency of the soluble oligomer used. In this study, we have analyzed the activation behavior using a mathematical model that describes the binding of multivalent ligands to cell-surface receptors. We show that a simple equilibrium binding model accurately describes the activation data for CD4(+) T cells treated with MHC-peptide oligomers of varying valency. The model can be used to predict activation and binding behavior for T cells and MHC oligomers with different properties.

Sex differences in central adrenoreceptor-mediated vasopressin response to hemorrhage.

Hemorrhage-induced changes in the plasma vasopressin concentration and mean arterial blood pressure (MABP) were studied in conscious rats of both sexes with and without central alpha 1-adrenoreceptor blockade. Rats were subjected to two sequential hemorrhages (H1 and H2), each 0.8% of body weight after an intracerebroventricular injection of the alpha 1-adrenoreceptor antagonist corynanthine or of vehicle. H1 stimulated vasopressin secretion more in proestrous females than in males; there were no significant sex-related differences in responses to H2. Corynanthine pretreatment attenuated the vasopressin response to H2 in males, potentiated this response in proestrous females, but had no effect in estrous females. MABP decreased after H1 in all female groups and in corynanthine-pretreated males. After H2, all groups were hypotensive to the same extent. These data indicate that central alpha 1-adrenoreceptor-mediated pathways participate in vasopressin and blood pressure responses to hemorrhage, but their role is complex and is dependent on gender and on the phase of the estrous cycle.

Nitroprusside treatment of erythromelalgia in an adolescent female.

OBJECTIVE: To report a case of erythromelalgia in an adolescent patient successfully treated with nitroprusside. CASE SUMMARY: A 15-year-old girl with erythromelalgia resistant to aspirin therapy received an infusion of nitroprusside. The response of the erythromelalgia to nitroprusside was dramatic, with complete pain resolution within 17 hours after the start of therapy. No relapse of erythromelalgia was seen when nitroprusside was discontinued and the patient remained well after 6 months. DISCUSSION: This case adds to existing literature substantiating the benefit of nitroprusside for the treatment of erythromelalgia in pediatric patients. Erythromelalgia in children may represent a different disease entity than that seen in adults, which is commonly responsive to aspirin therapy. The pathogenesis of erythromelalgia is unclear and precludes formulating a proposed mechanism by which nitroprusside has benefit in children. CONCLUSIONS: Nitroprusside is valuable for erythromelalgia resistant to aspirin therapy in pediatric patients. Because of unanswered questions regarding the disease, aspirin remains the agent of first choice in all patients with this rare disease.