The influence of female sex hormones on nasal reactivity in seasonal allergic rhinitis

BACKGROUND

This study aimed to investigate whether the hormone peaks of estrogen and progesterone could influence the extent of the allergic reaction in grass-pollen-allergic women.

METHODS

Twenty-three allergic women with seasonal allergic rhinitis due to grass pollen were included in this trial. Twelve were taking oral contraceptives (OC) (control group), and 11 were taking no pill (target group). The subjects were challenged with grass pollen by nasal provocation test around day 14 of their menstrual cycle (ovulation day) and again at the end of the cycle (day 27). The primary criteria were the subjective nasal symptoms rhinorrhea, nasal blockage, itching, and sneezing. A further criterion was the objectively measured nasal mucosal swelling, assessed by active anterior rhinomanometry. All criteria were evaluated before and 15 min after provocation, and the hormone status was determined on each investigation day.

RESULTS

Comparisons of symptoms between the groups resulted in P values of > 0.05 for all symptoms at both visits except the symptom blocked nose, which was significantly lower (P=0.03) in the patients with OC intake at visit 2, and the symptom sneezing, which showed a significantly (P=0.02) higher increase in patients taking OC at the end of the cycle. The flow decrease reached a greater extent in the target group than in the controls.

CONCLUSIONS

These results indicate a correlation of the hormonal situation and the nasal allergic reactivity. OC intake led to an intensifying of neurogenic symptoms near the end of pill intake, a result which could be due to a protective effect of the endogenous progesterone, in contrast to the orally administered hormones.

Nucleotide-dependent conformational changes in dynamin: evidence for a mechanochemical molecular spring

The GTPase dynamin plays an essential part in endocytosis by catalysing the fission of nascent clathrin-coated vesicles from the plasma membrane. Using preformed phosphatidylinositol-4,5-bisphosphate-containing lipid nanotubes as a membrane template for dynamin self-assembly, we investigate the conformational changes that arise during GTP hydrolysis by dynamin. Electron microscopy reveals that, in the GTP-bound state, dynamin rings appear to be tightly packed together. After GTP hydrolysis, the spacing between rings increases nearly twofold. When bound to the nanotubes, dynamin's GTPase activity is cooperative and is increased by three orders of magnitude compared with the activity of unbound dynamin. An increase in the Kcat (but not the K(m) of GTP hydrolysis accounts for the pronounced cooperativity. These data indicate that a novel, lengthwise ('spring-like') conformational change in a dynamin helix may participate in vesicle fission.

Importance of the pleckstrin homology domain of dynamin in clathrin-mediated endocytosis

The GTPase dynamin plays an essential role in clathrin-mediated endocytosis [1] [2] [3]. Substantial evidence suggests that dynamin oligomerisation around the necks of endocytosing vesicles and subsequent dynamin-catalysed GTP hydrolysis is responsible for membrane fission [4] [5]. The pleckstrin homology (PH) domain of dynamin has previously been shown to interact with phosphoinositides, but it has not been determined whether this interaction is essential for dynamin's function in endocytosis [6] [7] [8] [9]. In this study, we address the in vivo function of the PH domain of dynamin by assaying the effects of deletions and point mutations in this region on transferrin uptake in COS-7 fibroblasts. Overexpression of a dynamin construct lacking its entire PH domain potently blocked transferrin uptake, as did overexpression of a dynamin construct containing a mutation in the first variable loop of the PH domain. Structural modelling of this latter mutant suggested that the lysine residue at position 535 (Lys535) may be critical in the coordination of phosphoinositides, and indeed, the purified mutant no longer interacted with lipid nanotubes. Interestingly, the inhibitory phenotype of cells expressing this dynamin mutant was partially relieved by a second mutation in the carboxy-terminal proline-rich domain (PRD), one that prevents dynamin from binding to the Src homology 3 (SH3) domain of amphiphysin. These data demonstrate that dynamin's interaction with phosphoinositides through its PH domain is essential for endocytosis. These findings also support our hypothesis that PRD-SH3 domain interactions are important in the recruitment of dynamin to sites of endocytosis.

Environmental priming influences allergen-specific nasal reactivity

BACKGROUND

Preceding mucosal response to one allergen leads to the priming of the nasal mucosal response to another allergen. This study aimed to determine whether environmental allergens, especially ubiquitous animal dander, can induce nasal priming.

METHODS

We investigated 26 grass-pollen-allergic subjects with additional sensitization to other aeroallergens. We performed continuous allergen challenge for 2 h with 1500 Dactylis glomerata pollen/m3 in the Vienna challenge chamber. The nasal flow at 150 Pa was examined, and subjective scores were obtained every 15 min. Statistical analysis was calculated from the area under curve of nasal flow reduction by Student's t-test and the Mann-Whitney U-test. Alpha was 0.05.

RESULTS

In subjects with positive cat-dander RAST (class of > or = 3), besides grass-pollen allergy, the specific nasal allergic reaction to Dactylis challenge was significantly pronounced (P < 0.01), and an earlier onset of reaction was evident. The same results were obtained with additional sensitization to dog dander (P < 0.05). Concomitant sensitization to mugwort also led to escalating symptoms (P < 0.05).

CONCLUSIONS

These results indicate that a specific nasal allergic reaction is augmented by environmental priming caused by ubiquitous animal dander and possibly is influenced by the daily use of spices.

Rhinoresistometry versus rhinomanometry--an evaluation

Allergic nasal hyperreactivity is a common problem and many patients suffer from daily symptoms. Rhinomanometry is so far the only well established clinical method for objective assessment of nasal patency, although several expressions of nasal patency have been reported. Universal standardisation was achieved in 1983 in Brussels by Clement et al. [1], but many specialists are looking for a system giving more information on the functional aspects of the nose. A new development arising from active anterior rhinomanometry is rhinoresistometry. We tested this equipment, which has been introduced with new software for calculation and graphic presentation. 24 adult volunteers with proven allergy to grass pollen were examined immediately after long-term challenge in the Vienna Challenge Chamber [3] and 15 minutes after decongestion by application of 5% ephedrine solution. The similarity and differences between rhinomanometry and rhinoresistometry, as well as the value of the additional parameters are pointed out. Our data indicate that rhinoresistometry is a rapid, reproducible and non-invasive technique, which gives extended information in comparison to classic rhinomanometry. The results correlate very well with the findings obtained by the standard method. This pilot study demonstrates the benefit of the new parameters.

Efficacy and safety relative to placebo of an oral formulation of cetirizine and sustained-release pseudoephedrine in the management of nasal congestion

BACKGROUND

The aim of this study was to assess the clinical efficacy of an oral formulation of cetirizine 5 mg with sustained-release pseudoephedrine (PSE) 120 mg relative to placebo in patients with nasal congestion.

METHODS

Twenty-four patients with perennial rhinitis due to house-dust-mite (HDM) allergy were recruited in this crossover study. A treatment period of 1 week, in which cetirizine/PSE was administered twice daily, was followed by a washout period of at least 2 weeks and a further period of 1 week in which the alternative treatment was given to each patient. Immediately after the first dose of each medication (day 1), nasal congestion and related symptoms were assessed during a 7-h challenge with HDM feces, with the Vienna Challenge Chamber (VCC), to investigate onset of action of the preparation. A second challenge of 3-h duration, carried out at least 12 h after the final dose, was undertaken after 1 week (mean) of twice-daily treatment to assess residual effects of the formulation after achievement of steady state.

RESULTS

The oral formulation of cetirizine/PSE was significantly (P<0.001) superior to placebo in improving nasal obstruction during both challenges. The improvement in nasal airflow and nasal patency was significantly greater with cetirizine/PSE than with placebo (P<0.02). In addition, subjective assessment of nasal symptoms showed that cetirizine/PSE was significantly superior to placebo in both challenges for the sum of nasal obstruction scores (P<0.01). Both medications were well tolerated, and no serious adverse events occurred during the study.

CONCLUSIONS

In this study, cetirizine/PSE relieved nasal congestion and other objective and subjective symptoms to a significantly greater extent than placebo. No serious adverse events occurred, and both regimens were equally well tolerated.

Detection of mycobacterial infections using the Dieterle stain

Retrospective review comparing the modified Dieterle stain with standard acid-fast stains was performed on seven surgical pathology cases that contained culture-positive mycobacteria infections. Tissues examined comprised cervical and submandibular lymph nodes and soft tissues of the face and chest. Modified Dieterle staining was performed on paraffin-embedded tissue sections, and the results were compared with those of hematoxylineosin stains and auramine-rhodamines and carbolfuchsin acid-fast stains. The acid-fast stain showed organisms in three of seven cases on initial review and five of seven cases on retrospective review; the auramine-rhodamine stain retrospectively revealed organisms in five cases. In contrast, the Dieterle stain showed organisms in all seven sections on retrospective examination. Dieterle stains revealed either beaded bacilli or nocardia-like filamentous organisms, sometimes with abundant granular debris possibly representing degenerative organisms. In three cases in which bacteria were readily apparent with the Dieterle stain, only rare organisms could be identified with the acid-fast stain. The modified Dieterle stain was more sensitive than the acid-fast stain in the identification of mycobacteria in pediatric specimens, and its use is recommended in cases with necrotizing granulomas. However, its specificity is limited by morphologic similarities of the organisms to those of nocardiosis and cat scratch disease.

Diffuse idiopathic skeletal hyperostosis causing obstructing laryngeal edema

Diffuse idiopathic skeletal hyperostosis (DISH), or ankylosing hyperostosis ("Forestier's disease"), is an ossifying diathesis of unknown etiology. Diagnosis is primarily radiologic: osseous bridging of at least four contiguous vertebral bodies, a radiolucent line between the deposited bone and the anterior vertebral surface, large osteophytes and preservation of disk height especially in the cervical and lumbar spine. Although DISH is found in 6-12% of autopsy cases, clinical features are rare and consist primarily of swallowing disorders. A case of DISH is reported in which excessively enlarged cervical osteophytes led to edema of the laryngeal inlet and consequent severe dyspnea, necessitating emergency tracheotomy. Surgical excision of the osteophytic masses resulted in relief of symptoms. Symptomatology, radiographic features and individual treatments are discussed, with the latter dependent on clinical symptoms.

Calcium triggers calcineurin-dependent synaptic vesicle recycling in mammalian nerve terminals

BACKGROUND

Following exocytosis at the synapse, synaptic vesicle components are recovered by endocytosis. Morphological analysis has suggested that this occurs by a clathrin-mediated pathway, and the GTPase dynamin is thought to be involved in 'pinching off' endocytosing vesicles. The finding that the calcium-dependent phosphatase calcineurin can dephosphorylate dynamin and two other proteins implicated in endocytosis (amphiphysin and synaptojanin) has suggested a potential role for calcium and dephosphorylation in regulating synaptic vesicle endocytosis.

RESULTS

We tested this hypothesis with an endocytosis assay in isolated nerve terminals (synaptosomes) that relies on the use of the fluorescent dye FM2-10. In synaptosomes, vesicle recycling occurs predominantly via a pathway dependent on both dynamin and amphiphysin. We found that endocytosis could be stimulated maximally at calcium concentrations that yielded only low levels of exocytosis, suggesting that the two processes had different calcium sensitivities cyclosporin A and Fk506, we identified calcineurin as a calcium sensor for endocytosis and showed that its activity is essential for synaptic vesicle endocytosis in synaptosomes.

CONCLUSIONS

Our results suggest that dynamin-dependent synaptic vesicle endocytosis is triggered by calcium influx occurring upon nerve-terminal depolarisation. An essential mediator of calcium's effect is calcineurin, the activation of which leads to dephosphorylation of at least four proteins implicated in endocytosis-dynamin, amphiphysin 1, amphiphysin 2 and synaptojanin. Our findings also imply that endocytosis and exocytosis may occur in tandem in vivo simply because they share a responsiveness to calcium influx, rather than because they are mechanistically coupled.

Immunotherapy with sublingual birch pollen extract. A short-term double-blind placebo study

The aim of this double-blind placebo-controlled study was to evaluate the efficacy and tolerability of short-term birch pollen sublingual immunotherapy. Forty-one patients suffering from allergic rhinoconjunctivitis caused by Betula alba were included. Exclusion criteria were the following: undergoing immunotherapy within the last 2 years, contraindications to immunotherapy, pregnancy and nursing. The treatment schedule comprised a 28-day basic course, followed by a 3-month maintenance treatment. The evaluation of the parameters was performed before treatment and 4 months after the last maintenance dose. Skin prick test and conjunctival provocation test (CPT) in a dilution series were carried out to determine the threshold of the reaction. The objective parameters used were the diameter of the skin wheals and the lowest concentration, of the allergen extract to induce the symptoms of itching and reddening of the eyes. The allergic reaction in general was evaluated with the help of a 2-h birch pollen challenge in the Vienna Challenge Chamber (VCC); nasal flow and resistance was measured by rhinomanometry; and nasal secretion was quantified by weighing used handkerchiefs. Bronchial reactions were objectified by spirometry; subjective symptoms of the eyes, the nose and the bronchial tract were documented by the patients via a visual analog scale. Birch pollen specific IgE and IgG were evaluated by monoclonal antibody enzyme immunoassay before (T0) and after (T1) treatment. For statistics p < 0.05 was applied. At T0 there was no decisive difference in the in vitro and in vivo results between the two groups. After the treatment period (T1), actively treated patients showed a significantly higher tolerance to the birch pollen CPT (p < 0.01). The skin reaction was significantly lower than in the placebo group. Furthermore, actively treated patients produced less than half of the nasal secretion of placebo-treated patients during the challenge session. The rhinomanometry analysis during the challenge showed significant differences for verum and placebo in favor of the actively treated patients (p = 0.033). There was no significant difference in the specific IgE and IgG concentrations. The side effects and compliance during the treatment were comparable in both groups. In conclusion, sublingual immunotherapy is a well tolerated and clinically effective method of treatment.

Synovial effusion in reflex sympathetic dystrophy: an additional sign for diagnosis and staging

PURPOSE

To improve the present MRI criteria for diagnosis and staging of reflex sympathetic dystrophy (RSD) by including increased joint fluid as an additional MRI sign of RSD.

DESIGN AND PATIENTS

One hundred and fourteen extremities (69 affected and 45 contralateral controls) in 57 consecutive patients with RSD were evaluated using a 1.5-T unit. T1- and T2-weighted pulse sequences, often with fat suppression, were used before and after administration of intravenous contrast enhancement (Gd). Following T2-weighted image digitization the volume of synovial fluid was measured with a computer model.

RESULTS

Effusions were detected in 61% of the extremities suspected of RSD and in 44% of the contralateral control joints. The mean fluid quantity measured in the symptomatic articulation was 201 mm3. MRI diagnosis of RSD based on previously described criteria was done in 62% of the patients, yielding a sensitivity of 60%. Effusions were present in 79% of the false negative MRI cases. Retrospectively considering the presence of fluid as a potential positive criterion for RSD increases the sensitivity by 31% (to 91%).

CONCLUSIONS

Joint effusions are probably associated with early stages of RSD. Adding effusion to the list of radiological criteria for RSD increases the sensitivity of MRI from 60% to 91%.

Dose-dependent protection by azelastine eye drops against pollen-induced allergic conjunctivitis. A double-blind, placebo-controlled study

The efficacy and tolerability of azelastine (CAS 58581-89-8) eye drops at three different doses (0.025%, 0.05% and 0.1%) were investigated in a double-blind, randomized, placebo-controlled, crossover study in 24 subjects with a history of allergic conjunctivitis/rhinoconjunctivitis, who were challenged, out of season, by airbone allergen in the "Vienna Challenge Chamber" (VCC). Subjects received a single dose of azelastine eye drops 60 min before the start of a 4 h challenge in the VCC. Additional local challenge, mimicking a gust of wind, was administered 15 min before the end of the session. Each of the 4 study days was separated by a 2 week washout period. Azelastine eye drops showed a dose-dependent inhibition of the development of itching of the eyes. The effect was most pronounced 15 min after the additional local challenge. A maximal effect was achieved at a dose of 0.05%. Similar effects were observed on lacrimation. Azelastine eye drops also dose-dependently inhibited the degree of conjunctival redness, measured by digital imaging, and tended to reduce the low incidence of chemosis observed. Ranking of the results of all symptoms for each treatment group confirmed the optimal effect at a dose of 0.05%. Azelastine eye drops had no effect on nasal and bronchial symptoms or on measurements of airways function (FEV1). No adverse effects of the treatments were reported. The data support the use of 0.05% azelastine eye drops in the treatment of allergic conjunctivitis/rhinoconjunctivitis.

Effect of continuous allergen challenge on clinical symptoms and mediator release in dust-mite-allergic patients

This study investigated the early, prolonged immediate, and late-phase reactions of dust-mite-sensitive subjects undergoing long-term challenge in the Vienna challenge chamber (VCC) in terms of clinical symptoms and inflammatory mediator level patterns in nasal lavage fluids. A concentration of 70 ng Der p 1/m3 of air (feces of Dermatophagoides) was maintained over 8 h in the VCC. To show the clinical impact of this challenge model, the effect of a histamine H1-receptor antagonist that also has some antiallergic properties (loratadine) was also investigated. The study followed a double-blind, placebo-controlled, crossover design. Medication was given orally over 7 days before the provocation at a dose of 10 mg once daily. All 12 patients, whose dust-mite sensitivity was confirmed by disease history, skin prick test, and RAST, completed the challenge session. The documentation of the chosen parameters was performed every 30 min. Subjective nasal and ocular symptoms were assessed via a visual analog scale of 100 mm, nasal flow was recorded by active anterior rhinomanometry, and mediator release was evaluated with nasal lavages. Clinical aspect: the whole sample population showed a rise of nasal and ocular symptom severity and a nasal flow reduction, which were perceptibly, but not significantly attenuated by active drug treatment. Mediator pattern: in each patient, prostaglandin (PG)D2 and leukotriene (LT)C4 levels peaked within the first 2 h of provocation, PGD2 then moving toward baseline levels, and LTC4 then again rising continuously. Eosinophil cationic protein (ECP) exhibited a constant level increase over the whole provocation period, and tryptase levels did not change significantly. Whereas the area under the curve values of tryptase and ECP were higher in drug-treated patients than the placebo group, the early PGD2 peak occurring during the first two challenge hours seemed to be mitigated by loratadine. These results reveal that there is no link between the clinical symptoms, the drug efficacy, and the released mediators (LTC4, PGD2, ECP, and tryptase).

Predictors of BMI among adults with Down syndrome: the social context of health promotion

The study explored the relationship of diet, exercise, disability status, and degree of social integration to Body Mass Index, an indicator of excess weight and health status. Subjects were adults with Down syndrome living at home with their families. Variables included a 110-item nutritional analysis and assessments of family demographics, severity of disability, and "lifestyle" variables, such as friendship and affiliation, access to recreation and social activity, and level of physical activity. A factor analysis reduced lifestyle variables into three distinct factors representing friendship, social opportunity, and physical competency. Factor scores were entered into a hierarchical regression model that compared the variance predicted by these factors to the variance accounted for by diet, exercise, and health and physical status variables. Although the overall regression was not statistically significant, the final block of predictors, which represented friendship and social opportunity effects, accounted for a significant increment in BMI variance. Thus, even after the effects of diet, exercise, and physical status variables were partitioned out, the lifestyle variables remained potent predictors of BMI. Study conclusions are described in the context of current paradigms of health in the field of mental retardation and their relationship to inclusion in the community.

Breath-holding in healthy and pulmonary-compromised populations: effects of hyperventilation and oxygen inspiration

Suspension of respiration during end-expiration often is recommended to minimize body organ displacement between sequential image acquisitions. The purpose of this report is to evaluate techniques for end-expiratory breath-holding applicable to a pulmonary-compromised population. Eighty-seven consecutive outpatients with chronic pulmonary diseases and 31 healthy nonsmoking volunteers were recruited for the study. All subjects were asked to hold their breath in end-expiration while in the supine position (29 after breathing room air, 29 after hyperventilating room air for six breaths, and 29 after breathing O2 from a portable oxygen tank via nasal cannula until pulse-oximeter readings stabilized or reached 100%). Each volunteer was tested with all three methods. The mean length of time for a breath-hole on room air without hyperventilation was 9.2 seconds for the patients and 31.7 seconds for the volunteers. A breath-hold after hyperventilation of room air was timed at 12.3 seconds for the patients and 41.2 seconds for the volunteers, and after O2 administration, the breath-hold was 22.4 seconds for the patients and 60.9 seconds for the volunteers. No adverse effects occurred. The pulmonary-compromised patient can suspend respiration most successfully after O2 administration (P < .0001), whereas hyperventilation seems to be less beneficial. Nonpulmonary-compromised volunteers can hold their breath for longer periods of time.

Vaginal wall sling for anatomical incontinence and intrinsic sphincter dysfunction: efficacy and outcome analysis

PURPOSE

A prospective cohort study was done to determine the efficacy and clinical outcome of a new technique for anterior vaginal wall sling construction to treat urinary incontinence due to intrinsic sphincter dysfunction or anatomical incontinence.

MATERIALS AND METHODS

Preoperative evaluation included lateral cystography, video urodynamics, cystoscopy and incontinence staging. Postoperative subjective and objective staging outcome measures were prospectively assigned at predetermined regular intervals by a third party.

RESULTS

Of the patients 95 had intrinsic sphincter dysfunction and 65 had anatomical incontinence. The repair failed in 7% of the 160 patients who had recurrent incontinence during followup and 9% had de novo urgency incontinence. Time to failure comparing patients with intrinsic sphincter dysfunction and anatomical incontinence was modeled using Kaplan-Meier survival curves, and the log rank test showed no significant difference between the groups (p > 0.05). Logistic regression covariates revealed no significant predictive factors for postoperative failures. Preoperative patient age was the only predictive factor for de novo instability (logistic regression model p < 0.05).

CONCLUSIONS

Our initial results indicate that the 2 groups are indistinguishable to date based on current clinical and experimental statistics except for time to full recovery of postoperative voiding and incidence of postoperative instability (regression model p < 0.05).

The structure of the prostaglandin EP4 receptor gene and related pseudogenes

The EP4 prostaglandin receptor (EP4R) is a member of the seven transmembrane receptor superfamily. We have obtained the human EP4 receptor gene sequence and determined its structure relative to EP4R cDNA synthesized from peripheral blood lymphocytes. The EP4R gene spans approximately 22 kb and consists of three exons separated by two introns. The first exon (530 bp) is noncoding. After an intron of 472 bp, the second exon contains a short (43 bp) 5' sequence before a 289-amino-acid open reading frame (ORF). An 11.5-kb intron is found at the end of transmembrane 6, and the rest of the ORF is in exon 3. The gene structure is analogous to those of the thromboxane, PGI, and PGD receptors. The deduced initiation site does not contain a conventional TATA box but is 70% GC-rich and contains CCAAT boxes, SP1 and AP2 motifs, and motifs consistent with activation by proinflammatory cytokines. Southern blot analysis of human genomic DNA shows two genes with homology to the EP4R gene. Both appear to be pseudogenes with 70% amino acid identity to the EP4R up to the "ERY" sequence at the end of transmembrane 3, where an Alu-like repetitive sequence element was found. The ORF sequence is also interrupted by a stop codon. The pseudogenes differ in that one contains a second "repetitive element" (a line 1 repeat) in the 5' end of the ORF. Northern blot analysis of human mRNA using a pseudogene probe showed hybridization only to the EP4 receptor transcript. PCR also failed to detect expression of either pseudogene. This study defines the gene structure of EP4R and suggests the existence of two related pseudogenes.

Health characteristics and behaviors of adults with mental retardation residing in three living arrangements

Three hundred and twenty-nine subjects (aged 17-70 years) residing in an institution (N = 184), group home (N = 39), or with one or more family members (N = 106) were evaluated on body composition, blood lipids, and health behaviors. Subjects in the institutional group had lower body weights than those in the group home and natural family settings (p < .001) and also had lower BMIs and percent body fat levels compared to those in the natural family (p < .001). The institutional group also had lower total cholesterol and LDL-C levels than the group home and natural family groups (p < .001) and lower TG and ratio of total cholesterol to HDL-C than the natural family group (p < .01). Although overall use was quite limited, residents in the group home setting smoked more cigarettes, drank more alcohol and coffee, and exercised less than those in the institution and natural family (p < .001). Group home residents also exercised less. Health promotion and disease prevention initiatives for persons with mental retardation living in group homes, in supported living placements, and with their natural families should be undertaken and carefully evaluated.

High-dose chemotherapy-induced platelet defect: inhibition of platelet signal transduction pathways

Patients receiving high-dose chemotherapy and autologous bone marrow transplantation acquire a platelet secretion defect. The role of chemotherapeutic agents and their metabolites in mediating this platelet defect was investigated. 1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU), but not cyclophosphamide or cis-platinum, was found to inhibit platelet aggregation in vitro in response to activation by either ADP, thrombin, or collagen. Inhibition by BCNU was dose dependent and required preincubation of platelets with BCNU. After a 60-min preincubation, 30 microM BCNU produced 50% inhibition of platelets in platelet-rich plasma. The cyclophosphamide metabolites acrolein and 4-hydroperoxycyclophosphamide also inhibited platelet aggregation in a dose-dependent manner, with a requirement for preincubation. Platelet inhibition occurred at clinically relevant concentrations of BCNU and metabolites of cyclophosphamide. The effects of acrolein were totally prevented by coincubation with the sulfhydryl-protecting agents N-acetylcysteine and 2-mercaptoethanesulfonic acid, whereas the effects of BCNU were incompletely prevented. The mechanism of platelet inhibition was investigated next by examining protein phosphorylation in response to platelet agonists. Acrolein inhibited thrombin- and phorbol ester-induced phosphorylation of a 40-kDa polypeptide and other substrates, indicating a cellular defect in protein kinase C signaling. BCNU did not interfere with protein phosphorylation, indicating preservation of initial signaling pathways. Thus, chemotherapeutic agents and their metabolites inhibit platelet function by inhibiting distinct components of the intracellular activation pathways.

Empty sella syndrome associated with partial hypopituitarism (visualized on MRI scan)

The empty sella syndrome has become a rather frequent finding in magnetic resonance imaging (MRI) scanning. The usual presentation of empty sella syndrome involves an incidental finding on a computed tomography scan or an MRI scan. It is unusual to find empty sella syndrome associated with hypopituitarism. The authors describe such an unusual finding in a 54-year-old nulliparous woman.