Fas (CD95)-dependent cell-mediated immunity to Listeria monocytogenes

Two distinct and complementary pathways, one mediated by perforin and the other dependent upon CD95 (Fas), effect cell-mediated cytotoxicity. We examined the relative roles of these pathways in host defenses against the intracellular bacterial pathogen Listeria monocytogenes by using murine listeriosis as a model system. Mice which lacked both perforin and Fas (P0L0) were generated, and their responses to primary and secondary listeriosis were compared to those of wild-type (WT), Fas-deficient (L0), and perforin knockout (P0) mice. Relative to WT mice during primary listeriosis, P0 mice exhibited a reduced capacity to clear the infection from their spleens but not their livers whereas L0 mice had elevated bacterial titers in their livers and a modestly increased titer in their spleens. In contrast, bacterial titers in P0L0 mice were increased approximately 50- to 560-fold in their spleens and 230- to 1, 000-fold in their livers; eventual clearance of listeriae from both organs was significantly delayed. Furthermore, the resistance of P0L0 mice to secondary listeriosis was significantly reduced in their spleens and livers compared to that of WT, P0, or L0 mice. In vitro experiments indicated that immune cytotoxic T lymphocytes (CTL) lysed L. monocytogenes-infected hepatocytes primarily via a Fas-dependent, perforin-independent mechanism. The absence of Fas severely abrogated the lysis of infected hepatocytes by immune CD8(+) CTL. Taken together, these results provide the first evidence for Fas-dependent CTL-mediated lysis of L. monocytogenes-infected hepatocytes and demonstrate complementary roles for Fas and perforin in host defenses against an intracellular bacterial pathogen.     

Reversible segmental cerebral arterial vasospasm and cerebral infarction: possible association with excessive use of sumatriptan and Midrin

OBJECTIVE: To describe a patient who developed reversible segmental cerebral arterial vasospasm and cerebral infarction while taking excessive amounts of sumatriptan succinate and a combination drug (Midrin) consisting of isometheptene mucate, 65 mg, dichloralphenazone, 100 mg, and acetaminophen, 325 mg. DESIGN: Case report. SETTING: Tertiary care center. PATIENT: A 43-year-old man who developed a left occipital infarct after taking a total of 23 sumatriptan succinate tablets (25 mg per tablet) and 32 Midrin tablets during a 7-day period and who on digital subtraction angiography was shown to have segmental cerebral arterial narrowing in multiple vessels. An extensive evaluation for other possible risk factors for cerebral infarction was unrevealing. MAIN OUTCOME AND RESULTS: Discontinuation of sumatriptan and Midrin regimens and administration of nicardipine hydrochloride led to nearly total resolution of the angiographic findings, and the patient had no recurrent strokes. CONCLUSIONS: One should consider the diagnosis of drug-induced vasospasm in patients with cerebral infarction and a history of excessive use of sumatriptan and Midrin. The initial angiographic abnormalities may resemble those found in patients with primary angiitis of the central nervous system.     

A novel in vitro bladder pelvic nerve afferent model in the rat

OBJECTIVE: To develop an in vitro model to allow electrophysiological recordings from pelvic nerve afferents of the urinary bladder in the rat and to ascertain the stability and reproducibility of the model with time. MATERIALS AND METHODS: Six male Wistar rats (body weight approximately 100 g) were used in the study. The bladder (complete with accessory organs of prostate and seminal vesicles), urethra and penis, together with the attached pelvic nerve and L6/S1 nerve trunk, were removed intact and placed in a specially designed recording chamber containing oxygenated Krebs solution maintained at 30 degrees C. The bladder was catheterized urethrally and attached to a continuous-infusion pump and a pressure transducer. The L6/S1 nerve trunk was placed across a silicone-gel wall into a separate chamber containing liquid paraffin, in which multiunit recordings from pelvic nerve afferents originating from the bladder were made. The afferent nerve activities in response to repeated bladder distension with saline, at 0.04 mL/min for 8 min over 3 h, were compared using the paired t-test to assess the reproducibility of the model. Conduction velocity studies were also carried out to ascertain the proportion of C- and A delta-fibres in the multiunit recordings. RESULTS: Repeated bladder distension with saline over 3 h produced consistent and reproducible afferent nerve responses, signifying that the afferent nerves recorded in this study neither sensitize nor desensitize over time. This is an essential prerequisite when using this model to study the effects of pharmacological manipulation of the bladder on its afferent nerve response. Conduction velocity studies showed that approximately 30% of the afferent fibres recorded from were C-fibres with the remaining being A delta-fibres. CONCLUSIONS: An in vitro bladder pelvic nerve afferent model for the rat was developed successfully; it is stable and produces reproducible results with repeated bladder distension over at least 3 h.     

Role of mast cells, neutrophils and nitric oxide in endotoxin-induced damage to the neonatal rat colon

PURPOSE: Twelve synthetic spider toxin analogs were prepared in an effort to better understand the structure-activity relationships of the polyamine portion of argiotoxin-636 (Arg-636), a noncompetitive NMDA receptor (NMDAR) antagonist. METHODS: The 1,13-diamino-4,8-diazatridecane portion of the side chain of Arg-636 was systematically modified in an effort to further our knowledge of the structural requirements for the alkyl linker spacing between the amine nitrogens. Systematic isosteric replacement of each of the amine nitrogens in the polyamine moiety with either oxygen or carbon provided a series of compounds which were evaluated in vitro for NMDAR antagonist activity. RESULTS: One-half of the heteroatoms found in Arg-636 were removed to provide analogs which maintained in vitro potency below 1 microM. However, these simplified analogs produced similar or more pronounced effects on the cardiovascular system than Arg-636 in vivo. CONCLUSIONS: In this set of analogs, a minimum of three basic nitrogens in the side chain was required for maximum potency as NMDAR antagonists. Isosteric nitrogen substitutions in the polyamine chain reduced the in vitro potency of these analogs. An analog binding-conformation model was proposed to rationalize the inactivity of these isosterically substituted analogs.     

Biochemical composition of human peripheral arteries examined with near-infrared Raman spectroscopy

OBJECTIVE: To describe the clinical, serologic, and immunogenetic features of familial idiopathic inflammatory myopathy (IIM) and to compare these with the features of sporadic IIM. METHODS: Clinical signs and symptoms, autoantibodies, HLA-DRB1 and DQA1 alleles, and GM/KM phenotypes were compared among 36 affected and 28 unaffected members of 16 unrelated families in which 2 or more blood relatives developed an IIM. In addition, findings in patients with familial IIM were compared with those in 181 patients with sporadic IIM. The families included 3 pairs of monozygotic twins with juvenile dermatomyositis, 11 families with other siblings or relatives with polymyositis or dermatomyositis, and 2 families with inclusion body myositis. RESULTS: The clinical features of familial IIM were similar to those of sporadic IIM, although the frequency of myositis-specific autoantibodies was lower in familial than in sporadic IIM. DRB1*0301 was a common genetic risk factor for familial and sporadic IIM, but contributed less to the genetic risk of familial IIM (etiologic fraction 0.35 versus 0.51 in sporadic IIM). Homozygosity at the HLA-DQA1 locus was found to be a genetic risk factor unique to familial IIM (57% versus 24% of controls; odds ratio 4.2, corrected P = 0.002). CONCLUSION: These findings emphasize that 1) familial muscle weakness is not always due to inherited metabolic defects or dystrophies, but may be the result of the development of IIM in several members of the same family, and 2) multiple genetic factors are likely important in the etiology and disease expression of familial IIM, as is also the case for sporadic myositis, but DQA1 homozygosity is a distinct risk factor for familial IIM.     

Retinoic acid-induced stress protein synthesis in the mouse

We have previously demonstrated that stress proteins (SPs) are synthesized in tissues in which malformations are later observed following treatment with the developmental toxicant, retinoic acid (RA), on day 11 of gestation (GD 11). These proteins were not synthesized in tissues which did not present with malformations near partuition. The purpose of the present investigation was to determine if this correlation between early SP synthesis and later malformation was present at other times during gestation. CD-1 strain mice were dosed orally with corn oil or 100 mg/kg body weight RA on GD 10 or 13. Some of the mice in each group were given an intraperitoneal injection of 3H-leucine to label embryonic protein synthesis one hour after dosing with RA. These animals were sacrificed 1.5 hour later, and embryonic protein synthesis was determined by two-dimensional gel electrophoresis followed by autoradiography. Other animals in each group were sacrificed on day 17 of gestation, and fetuses were examined for the presence of malformations. Following treatment with RA on day 10 of gestation, malformations were observed in the forelimbs, the hindlimbs and the tail; heart defects were not observed. SPs of 20-25,000 and 90,000 relative molecular mass (Mr) were synthesized in the forelimb bud and tail; in addition, a second low molecular weight (20-25,000) and a 84,000 Mr SPs were synthesized in forelimb buds. No SPs were synthesized in the hindlimb bud or the heart. Following RA treatment on GD 13, cleft palate was observed in 58% of fetuses; no other malformations were found. Proteins of 34,000, 84,000 and 90,000 Mr were synthesized in craniofacial tissue; SPs were not observed in forelimb bud, hindlimb bud, heart or tail tissues at this time. Therefore, it appears that there may be a correlation between tissue-specific SP synthesis early in organogenesis and the presence of a malformation later in gestation.     

Characteristics of winter and summer aerosol mass and light extinction on the Colorado plateau

This paper focuses on the spatial variability of fine mass and extinction budgets taking data from the winter and summer months of 1992. The study area included southern California, southern Nevada, southern Utah, Arizona, and parts of New Mexico. Two types of monitoring sites were operated: intensive and secondary or satellite. At the intensive sites, all major aerosol species were measured as well as extinction or scattering. At the satellite sites, trace elements including sulfur and hydrogen, absorption, and gravimetric fine mass were measured. Where all aerosol species are measured, the spatial variability of extinction budgets is examined assuming an externally mixed aerosol. At the satellite sites, an approximated fine mass budget is derived and the variability of these budgets in space and time are examined. This effort was part of a study called Project MOHAVE (Measurement of Haze and Visual Effects) carried out with the principal objective of understanding the relative contribution of regional and local sources to visibility impairment on the Colorado Plateau and specifically, the Grand Canyon. Generally, the contribution of sulfates, organics, and absorption to extinction are about equal at 20-30% with the coarse mass fraction being about 10-20%. The one exception is in southern California where the nitrate contribution tends to be higher in the winter than summer. During the summer, concentration gradients tend to be spread out across the study area, while during the winter months, variability in concentration and budgets tends to occur on a smaller scale.