Preadolescent temperament and risky behavior: bicycling across traffic-filled intersections in a virtual environment

OBJECTIVE

This investigation used a bicycling simulator to examine how preadolescent temperament is related to risky behavior.

METHODS

Children aged 10 and 12 years (N = 109) rode a bicycle through a virtual environment where they crossed intersections with continuous cross traffic. Mothers filled out the Early Adolescent Temperament Questionnaire-Revised.

RESULTS

Older children and male participants timed their entry into the intersection more precisely than did younger children and female participants, as did 10-year-old children higher in inhibitory control and 10-year-old boys higher in aggression. However, only 10-year-old children higher in inhibitory control had more time to spare when they cleared the intersection. For 10-year-old boys higher in aggression, cutting in more closely behind the lead vehicle was accompanied by less stopping at intersections, less waiting before crossing, and choosing smaller gaps to cross.

CONCLUSIONS

The Discussion section focuses on inhibitory control as a protective factor and aggression as a risk factor for car-bicycle collisions.

Unexpected Thrombocytopenia and Anemia in Cynomolgus Monkeys Induced by a Therapeutic Human Monoclonal Antibody

Cynomolgus monkeys dosed with a therapeutic monoclonal antibody (mAbY.1) at ≥50 mg/kg had unexpected acute thrombocytopenia (nadir ∼3,000 platelets/µl), sometimes with decreases in red cell mass. Increased activated macrophages, mitotic figures, and erythrophagocytosis were observed in the spleen. Binding of mAbY.1 to cynomolgus peripheral blood cells could not be detected in vitro. mAbY.1 induced phagocytosis of platelets by peripheral blood monocytes from cynomolgus monkeys, but not from humans. mAbs sharing the same constant domain (Fc) sequences, but differing from mAbY.1 in their variable domains, bound competitively to and had similar biological activity against the intended target. None of these antibodies had hematologic liabilities in vitro or in vivo. Neither the F(ab’)2 portion of mAbY.1 nor the F(ab’)2 portion on an aglycosylated Fc (IgG1) framework caused phagocytosis of platelets in vitro. These data suggest that the hematologic effects of mAbY.1 in cynomolgus monkeys likely occurred through an off-target mechanism, shown to be driven by 1 to 3 amino acid differences in the light chain. The hematologic effects made mAbY.1 an unsuitable candidate for further development as a therapeutic agent. This example demonstrates that nonclinical safety studies may be essential for understanding off-target effects of mAbs prior to clinical trials.

A delayed Boerhaave's syndrome diagnosis treated by thoracoscopy in prone position

Boerhaave's syndrome or postemetic rupture of the esophagus, carries a high morbidity and mortality. The authors report a delayed Boerhaave's syndrome diagnosis (3 days), successfully treated by right thoracoscopic debridement in prone position. Thanks to gravity the cardiopulmonary bloc drops back and the access to the esophagus is direct allowing for accurate placement of the chest tubes near the perforation. The procedure is completed by laparoscopic placement of a feeding jejunostomy with the patient supine.

[The first our quintet or the channel of care for the most usual urgent pathologies]

The European Community has named five emergencies as being priorities. These five emergencies are: the cardiorespiratory arrest, the myocardial infarction, the severe polytrauma, the cerebral vascular accident and the severe acute dyspnoea. In this article three of them are discussed. Seen with the eyes of a generalist the severe polytrauma requires simple gestures, such as an early call for help by the SMUR, axialisation of head, trunk and members, compression of overtly sources of bleeding and opening the airway to facilitate breathing. The acute myocardial infarction continues to pose problems of diagnosis. The pathognomonic presentations are the STEMI and the N-STEMI infarction. In these cases it is a priority to call for the help of a SMUR unit. In the case of a STEMI infarction it is an absolute priority to admit the patient quickly to hospital and to directly move on to the coronarography ward for a primary angioplasty procedure. Within the first three hours of the infarction, if primary angioplasty is not a possibility within the first 90 minutes, thrombolysis is absolutely indicated. In the case of N-STEMI infarction a quick admission to a coronary care unit is urgent but the treatment is mainly medical. The cerebral vascular incident occurs more frequently than the myocardial infarction, but, culturally, not enough importance is attached to this pathology. Within the first three hours the aim is to get the patient to an emergency department (by means of the SMUR), to evaluate the coagulation values of the patient and to perform a head scan (without the injection of contrast) of good quality. If the patient is not too severely incapacitated (NIH score between 4 and 25), if the head scan does not show a hemorrhagic lesion and if there is no contraindication for thrombolysis, Actilyse should be administered. The time it takes to do all of these acts can not exceed the above mentioned three hours.

Amine Modulation of Ih in a Small Neural Network

We studied the functional role and modulation of the hyperpolarization-activated inward current ( Ih) in the pyloric network of the lobster stomatogastric ganglion. In isolated neurons, Ih is a small current with a hyperpolarized voltage of half-activation ( VAct) and a slow time constant of activation (τAct). Bath application of dopamine (DA), octopamine (OCT), or serotonin (5HT) modified Ih in selected synaptically isolated pyloric neurons. DA significantly enhanced Ih in the anterior burster (AB) neuron by depolarizing its VAct, accelerating its τAct, and enhancing its maximal conductance ( gmax). DA more weakly enhanced Ih in the pyloric constrictor (PY) and ventricular dilator (VD) neurons. OCT weakly depolarized VAct and accelerated τAct in the VD and inferior cardiac (IC) neurons. 5HT depolarized VAct in the IC neuron. Under control conditions with intact modulatory inputs from other ganglia, the pyloric rhythm cycles strongly at about 1–2 Hz. Bath application of the Ih blocker cesium (Cs+) caused a mean increase in the period of 8%, although this effect was highly variable. When Cs+ was applied to an isolated ganglion where the pyloric rhythm had been activated only by DA, the cycle period was consistently increased by 13.5%, with no other strong changes in rhythm parameters. These results suggest that Ih regulates the pyloric rhythm by accelerating AB pacemaker frequency, but that this effect can vary with the modulatory conditions.

Surgical technique and complications during laparoscopic repair of diaphragmatic hernias

Diaphragmatic hernias can present as retrocostoxiphoid hernias (RCXH) or diaphragmatic dome hernias. The RCXH include the Larrey hernia (LH), the Morgagni hernia (MH), and the Larrey-Morgagni hernia (LMH). These congenital hernias are usually asymptomatic, and the diagnosis is simplified by two exams: chest X-ray, and thoraco-abdominal computed tomography (CT) scan. The potential risk in this condition is small-bowel incarceration in the hernia defect and subsequent obstruction. We report two cases of LH and one case of LMH treated by laparoscopy between February 2004 and October 2005, with a review of the surgical techniques. Two different laparoscopic techniques were used: the tension-free technique, and resection of the hernia sac with closure of the defect and reinforcement by prosthesis. One patient presented a postoperative cardiac tamponade due to a clip-induced bleeding of an epicardial artery at the inferior surface of the heart. Treatment by laparoscopy is feasible, but a consensus regarding the best laparoscopic repair is needed.

Haptoglobin directly affects T cells and suppresses T helper cell type 2 cytokine release

T helper cell type 1 (Th1) and type 2 (Th2) immune responses are characterized by a different pattern of cytokine expression following T-cell activation. Alterations of the ratio of Th1 to Th2 cells are important determinants of susceptibility to viral and parasitic infections, allergies, anti-tumour responses, and autoimmunity. In this work we bring new evidence for an effect of haptoglobin (Hp), a positive acute-phase protein, on T-lymphocyte functions. We show that Hp specifically interacts with both resting and activated CD4+ and CD8+ T cells. This specific binding results in a strong suppression of induced T-cell proliferation. In addition, Hp exhibits a strong in vitro inhibitory effect on Th2 cytokine release, while the production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) is only slightly inhibited at high Hp doses. As a result, the presence of Hp promotes Th1 activation over Th2 activation in vivo as evidenced in Hp-deficient mice. Anti-CD3 monoclonal antibody injection indeed resulted in predominant IL-4 production in Hp-/- mice, in contrast to predominant IFN-gamma production in Hp+/+ mice. We conclude that Hp plays a modulating role on the Th1/Th2 balance by promoting a dominant Th1 cellular response. This points to a role of acute-phase proteins in balancing immune responses.

Daclizumab (Zenapax) inhibits early interleukin-2 receptor signal transduction events

Daclizumab, a humanized antibody against the interleukin-2 (IL-2) receptor (R) alpha-chain, is a promising new immunosuppressant in transplantation. As its exact mechanism of action has remained unclear, we examined its short-term effects on primary human T lymphocytes expressing the high-affinity IL-2R. Daclizumab exposure for 20 min neither affected T cell viability nor their surface expression of the IL-2R alpha-, beta-, or gamma-chains. However, after IL-2 stimulation (200 U/ml, 20 min), immunoblots of cell lysates demonstrated attenuation of the IL-2-induced tyrosine phosphorylation of 65-75 kDa proteins by Daclizumab, but not by isotype controls. Since this is the molecular weight of the IL-2R beta- and gamma-chains, which are both tyrosine-phosphorylated by IL-2, we next examined the effect of Daclizumab on their IL-2-induced tyrosine phosphorylation. In immunoblots of IL-2R beta- and gamma-chain-immunoprecipitates the tyrosine phosphorylation of both chains by IL-2, but not by IL-15, was attenuated in the presence of Daclizumab. Furthermore, co-immunoprecipitation experiments showed that Daclizumab inhibited the IL-2-induced association of these chains, a prerequisite for their mutual tyrosine phosphorylation. Lastly, we demonstrated that Daclizumab inhibits the receptor-downstream induction of the IL-2-activated DNA-binding protein STAT5 in gel shift assays. We conclude that Daclizumab directly and specifically interferes with IL-2 signaling at the receptor level by inhibiting the association and subsequent phosphorylation of the IL-2R beta- and gamma-chains induced by ligand binding. Under our experimental conditions, Daclizumab had no effects on cell viability, and it did not modulate the surface expression of the IL-2R alpha-, beta-, or gamma-chains.

Treatment for postdural puncture headache associated with late postpartum eclampsia

Postdural puncture headache (PDPH) is the most common complication of accidental or deliberate dural puncture. It also occurs after epidural or spinal analgesia for labor and delivery. Treatment may be conservative with analgesics and/or caffeine. Definitive treatment can be accomplished with an epidural blood patch (EBP). We present a case of postpartum convulsions which were temporally related to a caffeine infusion and an EBP.

Spontaneous T-cell proliferation in the non-obese diabetic mouse to a peptide from the unique class II MHC molecule, I-Ag7, which is also protective against the development of autoimmune diabetes

AIMS/HYPOTHESIS

Major histocompatibility complex class II molecules present antigenic peptides to T-cells and have an important role in T-cell thymic education. The mechanism by which major histocompatibility complex alleles confer a high genetic risk for autoimmune diabetes is not known. One hypothesis is that during positive thymic selection, the peripheral T-cell repertoire is modelled by major histocompatibility complex-restricted presentation of self major histocompatibility complex molecule-derived peptides, some of which mimic tissue autoantigens. The sequence similarity between a known T-cell epitope of glutamic acid decarboxylase-65, 509:VPPSLRTLED and the non-obese diabetic mouse class II major histocompatibility complex molecule I-Ag7 86:VPTSLRRLEQ is consistent with this.

METHODS

We measured spontaneous proliferation of peripheral T-cells from non-obese diabetic mice and other, non-diabetes-prone strains, to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, binding of these peptides to intact I-Ag7 and assessed the effect of tolerance induction on diabetes development, by injecting young non-obese diabetic mice with high doses of peptide.

RESULTS

T-cells from non-obese diabetic, but not other mice strains, spontaneously proliferate to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, but not control peptides. Both test peptides bind I-Ag7. Tolerance induction prolongs diabetes-free survival in non-obese diabetic mice when either the I-Ag7 86-101 or glutamic acid decarboxylase-65(509-524) peptide, but not control peptide, is used.

CONCLUSION/INTERPRETATION

A peptide from the unique class II major histocompatibility complex, diabetes-susceptibility molecule, I-Ag7, presented by I-Ag7 is a target of T-cell responses in diabetes-prone nonobese diabetic mice and tolerance induction against the peptide offers appreciable protection against the development of diabetes.

Determinants of mortality in elderly patients with heart failure: the role of angiotensin-converting enzyme inhibitors

BACKGROUND

Despite randomized controlled trials demonstrating mortality reduction, many studies have documented persistent low rates of prescription of angiotensin-converting enzyme inhibitors (ACE-I) in patients with heart failures; the reasons for this pattern remain poorly defined. In addition, some authors have argued that the results of carefully controlled clinical trials do not translate well into the uncontrolled world of clinical practice, and the mortality benefits of ACE-I may not extend into special populations such as the elderly.

OBJECTIVES

To understand the reasons for failure to prescribe ACE-I to Medicare patients with heart failure and to assess the impact of this failure on mortality.

METHODS

We obtained data by reviewing charts of Medicare patients discharged from 7 Colorado hospitals with a diagnosis of heart failure during 1994.

RESULTS

We identified a diagnosis of heart failure in 1016 patients without a contraindication to ACE-I. Three hundred seventy-eight of these patients were receiving ACE-I at the time of admission. Of the 638 remaining, 257 had their left ventricular systolic function assessed and 92 had diminished function. Of these 92, 50 (54.3%) were discharged on a regimen of ACE-I. The only significant difference in baseline comorbidity or demographic variables between those given and those not given ACE-I was that patients not prescribed ACE-I were older. Using multivariate analysis, younger age and cardiology consultation predicted ACE-I prescription (P = .02). By life-table analysis, mortality at 1 year following discharge from the index hospitalization was lower in those treated with ACE-I than in those not so treated (P = .03). The Deyo index of comorbidity, prescription of an ACE-I, site of treatment, and presence or absence of cardiology consultation were significantly associated with 1-year mortality by multivariate analysis (P<.001).

CONCLUSIONS

Underinvestigation and undertreatment of chronic heart failure persists. Failure to treat elderly patients with ACE-I is associated with a mortality that appears to be greater than that seen in the placebo arms of large clinical trials of ACE-I therapy. Within the population studied, older patients are less likely to be treated. Failure of age to significantly add to prediction of mortality implies that the apparent bias against treating older patients with chronic heart failure with ACE-I is not justified. Because mortality is dependent on provider and site of treatment, further reductions in mortality from chronic heart failure may require intensive and selective local efforts, or development of regional heart failure centers.

Severe hyperthermia during tetrabenazine therapy for tardive dyskinesia

We recently observed a 45-year-old patient with a history of psychiatric illness who presented with severe hyperthermia (rectal temperature above 41 degrees C) with intense rhabdomyolysis and liver cytolysis during tetrabenazine therapy for neuroleptic tardive dyskinesia. In addition to tetrabenazine, this patient took lorazepam and two antidepressant drugs: clomipramine, a potent serotonin-reuptake inhibitor, and mianserin. Hyperthermia responded to parenteral sodium dantrolene and oral bromocriptine administration. The significant role of tetrabenazine (a central nervous system dopamine-depleting drug) and the contribution of antidepressants to the mechanism of this neuroleptic malignant syndrome - like hyperthermia are discussed.

Clinical spectrum associated with positive ANCA titres in 94 consecutive patients: is there a relation with PR-3 negative c-ANCA and hypergammaglobulinaemia?

OBJECTIVE

To calculate the positive predictive value (ppv) of cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCAs) and anti-proteinase 3 (PR 3) antibodies for Wegener's granulomatosis (WG) and to evaluate their association with other diseases.

METHODS

The clinical files of all 94 patients who had a positive c- or perinuclear (p)-ANCA test, or both, in the laboratory of the University Hospital, Leuven between April 1995 and March 1996 and who attended the Internal Medicine Department of the hospital were retrospectively studied.

RESULTS

Of the 94 patients with ANCAs (fluorescence titre > or = 1/40), 57 were c-ANCA positive and 45 p-ANCA positive (eight were simultaneously c- and p-ANCA positive). Of the 57 c-ANCA positive patients, 23 had WG. The ppv for WG thus was 40%. This value did not increase by defining a higher threshold for a positive ANCA. There was not a good relation between ANCA titres and disease activity in the WG patients, nor was there a relation between anti-PR 3 antibody levels and WG disease activity. The ppv of anti-PR 3 antibodies for WG however was very high (85%). There was a positive correlation between the level of (hyper) gammaglobulinaemia and c-ANCA titres in those patients with final diagnoses not known to be associated with c-ANCA. Forty five patients had positive p-ANCAs. The largest group were those with inflammatory bowel disease (n = 20, of whom the majority had colitis ulcerosa or primary sclerosing cholangitis, or both); the great majority of these patients had no anti-myeloperoxidase antibodies. Vasculitis was present in eight patients, of whom two had WG (both were also c-ANCA positive).

CONCLUSION

There is a low ppv of c-ANCAs for WG, caused by a high percentage of PR 3 negative, positive c-ANCA determinations, possibly related to hypergammaglobulinaemia. Anti-PR 3 antibodies have a high ppv for WG. However, neither c-ANCA titre, nor the level of anti-PR 3 antibodies correlated with the activity of the disease.

Counterimmunoelectrophoresis with serum prediffusion: an improved method for the detection and identification of antibodies against extractable nuclear and cytoplasmic antigens

In the technique of counterimmunoelectrophoresis (CIE) with serum prediffusion (SPD) serum is allowed to diffuse freely into the gel before pouring the antigenic extract in its trough (or wells) and starting the electrophoresis. Both the immunoprecipitations and the interactions with reference sera are strongly intensified by SPD, leading to higher sensitivity and specificity for the detection of anti-SSA/Ro, anti-SSB/La, anti-U1RNP, anti-Sm, anti-Jo1 and even anti-Scl-70 antibodies. We found that the optimal SPD time was 2 h. To evaluate the relevance of SPD for the clinical laboratory, 92 antinuclear antibody (ANA) positive sera were tested on CIE without SPD and with 2 h SPD in identification tests with SSA/Ro, SSB/La, Sm, U1RNP and Jo1 reference sera (rsa). The precipitation lines and their interactions were evaluated by three independent observers. It was observed that SPD considerably improved the efficiency of CIE for antibody identification. The mechanisms underlying the intensification of the precipitation lines by SPD are discussed as are the characteristics of the CIE in comparison with other test systems such as the enzyme linked immunosorbent assay (ELISA) and immunoblot.

Human immunodeficiency virus in plasma and genital secretions during the menstrual cycle

Six human immunodeficiency virus (HIV)-positive women were studied weekly over 8 weeks to detect HIV RNA in plasma and cervical secretions and proviral DNA in cervical, vaginal, and cervicovaginal lavage samples by polymerase chain reaction (PCR) amplification techniques. In cervical swab samples, cell-free HIV RNA was detected more frequently than cell-associated HIV proviral DNA (22/48 vs. 7/48, respectively). Cervical HIV RNA was consistently detected in 2 women with plasma HIV RNA > 100,000 copies/mL but was not detected in 2 women with plasma HIV RNA < 10,000 copies/mL, regardless of menstruation status. HIV-specific IgA was detected in the plasma of 2 women and in at least 1 cervicovaginal lavage sample from all 6 women. Thus, quantitation of cervical HIV RNA can be accomplished by PCR techniques and may be useful in evaluation genital viral shedding.

Pregnancy in women with cerebrospinal shunts: a literature review and case report

Hydrocephalus is a rare condition that was debilitating until silicone tubing, developed in the late 1950s, allowed surgical treatment to be successful. Women successfully treated for hydrocephalus lead full lives including pregnancy and birth. The review of medical literature and the case report that follow reveal 47 cases of pregnancy in women with cerebrospinal shunts. Owing to the rarity of this condition, anecdotal case reports are the only source for learning about how cerebrospinal shunts may be affected by pregnancy. Theoretic concerns that the second stage of labor could be problematic appear to be unfounded. In addition, case reports indicate that decisions regarding mode of delivery, analgesia, and anesthesia should be based on obstetric concerns.

Deficient nitric oxide responsible for reduced nerve blood flow in diabetic rats: effects of L-NAME, L-arginine, sodium nitroprusside and evening primrose oil

1. This study examined the potential role of impaired nitric oxide production and response in the development of endoneurial ischaemia in experimental diabetes. Rats were anaesthetized (Na pentobarbitone 45 mg kg-1, diazepam 2 mg kg-1) for measurement of sciatic nerve laser Doppler flux and systemic arterial pressure. Drugs were administered into the sciatic endoneurium via a microinjector attached to a glass micropipette. 2. In two separate studies comparing diabetic rats (streptozotocin-induced; 8-10 wk duration) with controls, nerve Doppler flux in diabetic rats (Study 1, 116.6 +/- 40.4 and Study 2, 90.1 +/- 34.7 (s.d.) in arbitrary units) was about half that measured in controls (219.6 +/- 52.4 and 212.8 +/- 95.5 respectively; P < 0.005 for both). There were no significant differences between the two in systemic arterial pressure. 3. Inhibition of nitric oxide production by microinjection of 1 nmol L-NAME into the endoneurium halved flux in controls (to 126.3 +/- 41.3 in Study 1 and 102.1 +/- 38.9 in Study 2; both P < 0.001), with no significant effect in diabetic rats, indicating markedly diminished tonic nitric oxide production in the latter. D-NAME was without effect on nerve Doppler flux. 4. L-Arginine (100 nmol), injected after L-NAME, markedly increased flux in controls (by 65.8% (P < 0.03) and 97.8% (P < 0.01) in the two studies) and by proportionally similar amounts in diabetic rats [75.8% (P < 0.001) and 60.2% (P < 0.02)]. The nitro-donor, sodium nitroprusside (SNP; 10 nmol) had similar effects to L-arginine in both groups (increases of 66.0% in controls and 77.5% in diabetics; both P < 0.002). 5. A second diabetic group, treated with evening primrose oil performed exactly like control rats in respect of responses to L-NAME, L-arginine and SNP. 6. These findings implicate deficient nitric oxide in nerve ischaemia of diabetes and suggest correction thereof as a mechanism of action of evening primrose oil.

Targeted delivery of nerve growth factor via fibronectin conduits assists nerve regeneration in control and diabetic rats

This study examined the influence of fibronectin conduits joining two halves of a sectioned sciatic nerve, with and without preimpregnation with nerve growth factor, on regeneration in rats with streptozotocin-induced diabetes mellitus. Regeneration, measured morphometrically in fibres containing immunoreactivity to calcitonin gene-related peptide (CGRP) and GAP-43, was significantly less (P < 0.0001 for all comparisons) in diabetic rats with fibronectin mat grafts without nerve growth factor compared to similarly treated controls. Regeneration distances in diabetic rats were reduced to 43% (CGRP-reactive fibres) and 44% (GAP-43-reactive fibres) of controls, and the total amounts of immunoreactivities in the conduits were also reduced, though by lesser amounts (55 and 61% of controls respectively). Impregnation of the conduits with nerve growth factor before implantation increased the distance and amounts of regenerating immunoreactivity in both control and diabetic rats for both CGRP and GAP-43, such that these regeneration parameters were similar in nerve growth factor-treated diabetic rats to those in control rats implanted with untreated fibronectin mat conduits. These findings implicate impaired neurotrophic support in the defective regeneration characteristic of diabetic. neuropathy.

After the intensive care nursery experience: families' perceptions of their well being

This article describes family well being after a child's intensive care nursery experience. Thirty families of children who were graduates of intensive care nurseries participated in the study. Fifteen families of children with identifiable disabilities and 15 families of children with no identifiable disabilities were interviewed and completed standardized questionnaires. A comparison of family well being was done across three dimensions: the child's characteristics and caregiving needs, the family's support resources and needs, and the family's values and beliefs regarding their child's hospitalization and resulting special needs. Both groups of families had realized a renewed sense of meaning concerning family, children, and life itself due to their child's medical crises or disability. Families of children with disabilities, however, noted their financial concerns, burdens with their child's caregiving, and their difficulty in locating services for their child. These families' experiences underscore the need for a coordinated transition from the hospital to the community for the family and child.

CT findings in nonmucosal eosinophilic gastroenteritis

A 22-year-old patient with eosinophilic gastroenteritis with predominantly submucosal and muscular involvement is presented. The benefits of CT, using water as an orally administered contrast agent, are stressed, because CT enabled the authors to suggest a full thickness biopsy, after mucosal biopsies had remained repeatedly negative.

Recognition of tyrosinase by tumor-infiltrating lymphocytes from a patient responding to immunotherapy

The observation that allogeneic melanoma cells matched for particular HLA class I alleles stimulate T-cells isolated from patients suggests that widely shared antigens exist on these tumors. A transient expression system was developed for screening a melanoma complementary DNA library using the highly transfectable human kidney cell line 293. Using this system, large numbers of complementary DNA clones can be rapidly screened for the expression of antigens which stimulate T-cells. Tumor-infiltrating lymphocytes from patient 888, which recognized melanoma in the context of HLA-A24, were used to screen a complementary DNA library made from the autologous melanoma. Our results demonstrate that these tumor-infiltrating lymphocytes recognize tyrosinase, a gene previously shown to be recognized by T-cells only in the context of HLA-A2. These data demonstrate that a single antigen can be recognized in the context of two different class I HLA alleles. In addition, this study suggests that recognition of tyrosinase by antigen-specific T-cells may be involved in tumor rejection.

Genetic structure of Neisseria gonorrhoeae populations: a non-clonal pathogen

Reproduction by binary fission generates a clonal genetic structure in bacterial populations in the absence of a high rate of recombination. The extent of recombination in natural populations of Neisseria gonorrhoeae was determined from an analysis of electrophoretically demonstrable allelic variation at structural genes encoding nine enzyme loci in 227 worldwide isolates. No significant linkage disequilibrium was evident in the population, indicating that recombination must be frequent, relative to binary fission. The genetic structure of N. gonorrhoeae was compared with that of Bacillus subtilis from an earlier study. Linkage disequilibrium was less extreme in the N. gonorrhoeae population than in the local population of B. subtilis, in which only modest clonal structure was evident. Thus, N. gonorrhoeae, unlike pathogens so far examined, has a non-clonal population structure. As expected in a freely recombining population, no correlation was found between electrophoretic genotype and serovar or auxotype.

Complete sequence of one copy of the psbA gene from the thermophilic cyanobacterium Synechococcus elongatus

One copy of the psbA gene which codes for the photosystem II reaction center D-1 protein from the thermophilic cyanobacterium Synechococcus elongatus has been sequenced. It is feasible that a disulfide bridge between D-1 Cys212 and D-2 Cys212 is responsible for the thermostability of the photosystem II reaction center from Synechococcus elongatus.

Recurrent meningococcal infections in a patient with congenital C5 deficiency

A congenital C5 deficiency was the cause of recurrent meningococcal disease in a 27-year-old man. The lack of serum bactericidal activity accounts for the higher incidence and the different course of Neisseria infections in patients with a deficiency of the late complement components. Early antibiotic treatment and vaccination with a capsular polysaccharide meningococcal vaccine (A,C,Y,W-135) should be considered.

Sn-chlorin e6 antibacterial immunoconjugates. An in vitro and in vivo analysis

Monoclonal antibody-Sn-chlorin e6 immunoconjugates were prepared by the site-selective covalent modification of the monoclonal oligosaccharide moiety. By carefully controlling the reaction conditions and introducing triethanolamine groups as axial ligands of the Sn moiety, conjugates with in vivo biodistribution properties similar to underivatized IgG were prepared. By varying the reaction conditions, conjugates were reproducibly prepared with a range of photosensitizer to mAb molar ratios from 1.6 to 10. Based on a competitive inhibition radioimmunoassay, conjugates prepared by this method showed selectivity and binding affinity comparable to the unmodified antibody. The immunoconjugates had only slightly lower singlet oxygen yields than that observed with the Sn-chlorin e6 precursor indicating that negligible aggregation or structural modification of the chromophores occurred during the synthesis process. In vitro cell killing experiments demonstrated that all conjugates possessed significant cytotoxic activity. Biodistribution studies in mice showed that conjugates prepared with axial ligands had significant serum retention 24 h after injection while conjugates prepared without the triethanolamine ligand were much more rapidly cleared. In vivo specificity was demonstrated using rats infected with Fisher immunotype I P. aeruginosa at a site in the left posterior thigh muscle. Target to background ratios exceeded 60 at 120 h after conjugate injection of the specific immunoconjugate, compared to a ratio of only 6 for a non-specific mouse IgG conjugate. Biodistribution patterns at 120 h post injection indicate that the conjugates were both biologically active and structurally intact.

Isolation, ultrastructure, and partial characterization of collagen from the perineurium of the Florida lobster, Panulirus argus

Highly concentrated extracellular filaments in the perineurium of the Florida spiny lobster, Panulirus argus, were isolated using ultracentrifugation and linear sucrose gradients. The pellet obtained was highly enriched for the filaments as observed by transmission electron microscopy. Fibril diameter and axial periodicity measurements were obtained from filaments positively and negatively stained with uranyl acetate. A period between 14.0 and 25.0 nm and an average fibril diameter of 15.0 nm were observed. The filaments proved resistant to solubilization by most conventional agents and by several collagenases. NaOH (0.1 M at 100 degrees C) safely dissolved the filaments for measurements of protein content by the Lowry method and carbohydrate content with anthrone reagent. These tests revealed a protein content of approximately 84% and a high carbohydrate content of approximately 15%. Polyacrylamide electrophoresis of an acid-pepsin filament extract revealed a highly concentrated band (approximately 100,000) corresponding to the alpha-1 and alpha-2 bands of vertebrate type I collagen. Wide angle X-ray diffraction yielded meridional reflections that confirmed the filaments as collagen when compared with mammalian collagen X-ray diffraction. The amino acid composition was determined with a computer-assisted Beckman amino acid analyzer, which showed a glycine content of 279 residues/1000. Hydroxylysine and hydroxyproline were present in lower concentrations than expected.

[Refractory arterial hypoxemia and interatrial right-left shunt in myocardial infarction of the right ventricle]

The authors report the case of a 63 year old woman who developed refractory arterial hypoxemia due to a right-to-left interatrial shunt through a patent foramen ovale during the acute phase of right ventricular infarction. The precarious haemodynamic condition of the patient contra-indicated surgical intervention and so the effects of the shunt were reduced by obstructing the atrial septal defect with the balloon of a Swan-Ganz catheter. The management of this type of shunt is discussed based on the degree of hypoxemia and the patient's haemodynamic status with reference to this particular case and a review of the literature.