Control of hindbrain motor neuron differentiation by the homeobox gene Phox2b

Motor neurons are a widely studied model of vertebrate neurogenesis. They can be subdivided in somatic, branchial and visceral motor neurons. Recent studies on the dorsoventral patterning of the rhombencephalon have implicated the homeobox genes Pax6 and Nkx2.2 in the early divergence of the transcriptional programme of hindbrain somatic and visceral motor neuronal differentiation. We provide genetic evidence that the paired-like homeodomain protein Phox2b is required for the formation of all branchial and visceral, but not somatic, motor neurons in the hindbrain. In mice lacking Phox2b, both the generic and subtype-specific programs of motoneuronal differentiation are disrupted at an early stage. Most motor neuron precursors die inside the neuroepithelium while those that emigrate to the mantle layer fail to switch on early postmitotic markers and to downregulate neuroepithelial markers. Thus, the loss of function of Phox2b in hindbrain motor neurons exemplifies a novel control point in the generation of CNS neurons.

Fine structure of the developing avian corneal stroma as revealed by quick-freeze, deep-etch electron microscopy

Corneal transparency depends on the precise organization of the stromal extracellular matrix. The morphology of the extracellular matrix of the embryonic and adult avian secondary posterior cornea was studied in glutaraldehyde-fixed, quick-frozen, deep-etched replicas with the electron microscope. Although the collagen fibrils changed from a loose network to a more ordered parallel lamellar arrangement during development, their mean diameter remained constant between 30.3 and 31.2 nm. Besides collagen fibrils, other extracellular matrix components were observed: (i) straight or Y-shaped cross-bridging interfibrillar 8-10 nm filaments with 18-22 nm globules; (ii) relatively loose networks of 10-20 nm beaded filaments, with a mean periodicity of 107 nm, often running perpendicular to the collagen fibrils and adhering to the plasma membrane of stromal cells at early developmental stages; (iii) straight or curved 6-12 nm strands forming sheets within the stromal matrix that progressively disappeared, whereas similar structures persisted at the Descemet's membrane-stroma interface; (iv) dense networks of filaments with 6-8 nm filaments, sometimes polygonally arranged, and a substructure of 2-3 nm filaments with globular domains, which progressively disappeared with maturation but remained at the Descemet's membrane-stroma interface; (v) polygonal networks of 9-10 nm filaments with globular domains adherent to the surface of cell plasma membranes at early developmental stages. The temporal expression of deep-etched supramolecular structural assemblies is compatible with that of the so-called 'interstitial basement membrane components' previously described. The quick-freeze and deep-etching method can reveal important aspects of the in situ organization of the corneal extracellular matrix.

A randomized, controlled trial of indinavir, zidovudine, and lamivudine in adults with advanced human immunodeficiency virus type 1 infection and prior antiretroviral therapy

A randomized, double-blind, multicenter study of indinavir, zidovudine, and lamivudine was conducted in 320 adults with human immunodeficiency virus type 1 (HIV-1) infection, </=50 CD4 cells/mm3, and extensive prior zidovudine therapy. Patients received indinavir, 800 mg every 8 h; zidovudine, 200 mg every 8 h, and lamivudine, 150 mg twice daily; or all 3 drugs for 24 weeks. In an intention-to-treat analysis, proportions of patients with HIV-1 RNA <500 and <50 copies/mL, respectively, at week 24 were 56% and 45% in the indinavir-zidovudine-lamivudine group, 3% and 2% in the indinavir group, and 0% in the zidovudine-lamivudine group. Observed mean CD4 cell increases were 95, 78, and 6 cells/mm3 in the three-, one-, and two-drug arms, respectively. Regimens were generally well tolerated. Patients with advanced HIV-1 infection benefit from triple therapy with indinavir, zidovudine, and lamivudine, although the proportion with optimal response appeared to be lower in patients with low CD4 cell counts.

Efficacy and safety of delavirdine mesylate with zidovudine and didanosine compared with two-drug combinations of these agents in persons with HIV disease with CD4 counts of 100 to 500 cells/mm3 (ACTG 261). ACTG 261 Team

To evaluate the antiretroviral activity of delavirdine mesylate, a non-nucleoside reverse transcriptase inhibitor of HIV-1, we performed a phase II, randomized, double-blind, multicenter trial comparing the three-drug combination of delavirdine with zidovudine and didanosine to two-drug combinations of these drugs. Patients with CD4 cell counts between 100 and 500 cells/mm3 without prior or <6 months of monotherapy with zidovudine or didanosine were randomized to one of four arms and observed on a follow-up basis for 48 weeks. In total, 544 patients were evaluated. In those assigned to the three-drug regimen, mean short-term (weeks 4-12) and long-term (weeks 40-48) change in CD4 cells from baseline were 49.3+/-8.1 and 65.4+/-13.4 cells/mm3, respectively; mean short-term and long-term HIV-1 RNA changes from baseline were -1.13 log10+/-0.12 and -0.73+/-0.12 copies/ml, respectively. These responses in CD4 cell counts and HIV-1 RNA levels were better in comparisons with each of the two-drug arms at all study points; however, differences were not consistently significant. Gastrointestinal side effects were experienced by 33% of patients (178 of 544), and 30% (121 of 407) receiving delavirdine experienced rash, only one case of which was severe. In this study, therapy with delavirdine + zidovudine + didanosine was safe and showed modest, but not always significant, antiviral activity and CD4 cell count benefit compared with two-drug regimens with these agents. Key

Climbing the Bending Vibrational Ladder in D13C15N by Hot Gas Emission Spectroscopy

Using a newly constructed Fourier transform emission apparatus, we have measured the threefold substituted HCN isotopomer, D13C15N, at 1370 K in the range from 450 to 700 cm-1. We could assign hot bands with upper states up to Kvl2 = 12(12). The assignments have been verified for states up to v2 = 5 by fitting with earlier room temperature absorption measurements of overtone and hot bands. The intensities are shown to be in qualitative agreement with the expected intensity pattern for such emission spectra. All the measurements for D13C15N have been combined in a single least-squares fit that includes approximately 2700 rovibrational lines which have a root-mean-square deviation on the order of 0.000 4 cm-1. The spectroscopic constants for the bending states v2 = 1, ellipsis,12 are reported, as well as for some combination states involving the other vibrational modes. We also give the spectroscopic constants of various states of DCN, D13C14N, and D12C15N which where obtained from room temperature absorption measurements. Copyright 1999 Academic Press.

Effect of pulse pressure on vascular smooth muscle cell migration: the role of urokinase and matrix metalloproteinase

Plasminogen activator (PA) expression plays an important role in smooth muscle cell (SMC) migration and may therefore contribute to mechanical force-induced arterialization of vein grafts. The aim of this study was to determine whether pulse pressure due to pulsatile flow modulates SMC migration via urokinase (u-PA)-dependent mechanisms. Using a perfused transcapillary culture system, human umbilical vein SMC were exposed to pulse pressures (0-56 mmHg), in the absence or presence of human umbilical vein endothelial cells (EC) by varying pulsatile flow rates (0 ml/min to 25 ml/min). SMC cultured in the absence of EC increased their migration following exposure to increased pulse pressure (248+/-14%). Both u-PA and matrix metallo-proteinase 1 (MMP-1) expression was significantly elevated in SMC exposed to pressure as compared to static controls. The role of proteases in the pulse pressure-induced enhancement of SMC migration was confirmed following pretreatment with aprotinin, an anti u-PA antibody and metalloproteinase inhibitors (181+/-14% for aprotinin vs. 256+/-25% for control, 108+/-4% for anti-u-PA antibody vs. 233+/-17% for non-immune IgG, and 114+/-9% for BB-94, 105+/-7% for BB-3103 vs. 222+/-5% for control). Using SMC derived from u-PA gene knock-out mice, the SMC migratory response to increased pulse pressure was completely inhibited despite a significant increase in MMP expression in these cells. These results suggest that pulse pressure due to pulsatile flow induces SMC migration in vitro via u-PA and MMP-dependent mechanisms. Moreover, u-PA gene deletion results in blunting of pressure-induced SMC migration despite the endogenous upregulation of metalloproteinase. Modulation of u-PA expression by pressure may thus represent an important mechanism whereby hemodynamic forces regulate smooth muscle cell migration.

The impact of intrauterine contraceptive devices on cytological findings from routine Pap smear testing

OBJECTIVE

To evaluate the impact of intrauterine contraceptive device (IUCD) use on the interpretation of routine Pap smears.

STUDY DESIGN

A retrospective case-control study.

PATIENTS AND METHODS

During a 2-year period, we evaluated the Papanicolaou (Pap) tests of 452 consecutive asymptomatic women of childbearing age who used a copper IUCD (study group), and 452 matched controls who practiced no contraceptive methods (control group).

RESULTS

Inflammatory exudate, inflammatory epithelial changes or extensive metaplastic cells were more commonly encountered among the IUCD user as compared with non-users (p < 0.05). No difference was noted in the detection rates of cervical squamous intraepithelial lesions in the two study groups.

CONCLUSIONS

It can therefore be concluded that the use of an IUCD does not increase the incidence of squamous intraepithelial lesions. Any abnormal Pap smear in an IUCD user should first be repeated after local vaginal treatment, if only to temporarily palliate the inflammatory cellular reaction which impedes unequivocal interpretation of the routine Pap smear.

Predictive power of clinical indicators for self-care deficit

PURPOSE

To describe the predictive power of a set of the best clinical indicators for the nursing diagnostic labels self-care deficit (SCD) and impaired physical mobility.

METHODS

Patient assessment data (physical examination and interview) were obtained from 414 hospitalized patients.

FINDINGS

Patients with the diagnostic label of self-care deficit were significantly older in age, had a greater number of nursing diagnoses, required greater assistance in activities of daily living, and were less mobile than those without the diagnostic label. While 18 of 32 clinical indicators were positively related to self-care deficit, five clinical indicators were sufficient to diagnose SCD.

CONCLUSIONS

Further development of the method may be useful in improving diagnostic accuracy and efficiency of nursing diagnoses.

Recovery from opioid anesthesia: the clinical implication of context-sensitive half-times

The context-sensitive half-time, the time required for a 50% decrease in drug concentration, has been proposed to predict the speed of recovery after infusions of i.v. anesthetics. We studied 40 patients to compare the clinical recovery characteristics of alfentanil and sufentanil. Patients were randomly allocated to receive either sufentanil/propofol (Group 1) or alfentanil/propofol (Group 2) total i.v. anesthesia by target-controlled infusions (TCI), assuming an equipotency ratio of 500:1. After discontinuation, times to tracheal extubation and to discharge from the postanesthesia care unit were measured, as were drug concentrations up to 24 h. The TCI bias was -17.1% for sufentanil and -16.9% for alfentanil. We found no difference in mean extubation times between the groups (48.7 min in Group 1 versus 46.4 min in Group 2), whereas discharge criteria were fulfilled significantly (P = 0.039) earlier after alfentanil (99.5 min) compared with sufentanil (131.3 min). The relative decrement values to tracheal extubation were 62.1% for sufentanil and 48.0% for alfentanil, compared with 75.7% and 65.0% for discharge, respectively. Based on a difference in propofol requirements, we suggest an actual sufentanil to alfentanil equipotency ratio of 1:300. We conclude that the decay in pharmacodynamic effect is not only the result of pharmacokinetics.

IMPLICATIONS

Computer simulations may help to anticipate the clinical behavior of anesthetic drugs. In a clinical setting, we tested whether the recovery characteristics after i.v. anesthesia could be explained by a pharmaco-kinetic value, which describes the decline of drug concentrations in the body. This was not fully achieved.

High incidence of upper gastrointestinal tract involvement in Crohn's disease

A better definition of gastric mucosal histology in Crohn's disease permits a more accurate estimation of the frequency of upper gastrointestinal tract involvement in Crohn's disease. In a retrospective study of 792 patients with known Crohn's disease the incidence of lesions associated with the disease was determined in the duodenum, duodenal bulb, and gastric antrum and body mucosa. Crohn's disease was identified histologically in the antrum in 41.5%, in the body in 37.1%, in the duodenum in 12.1%, and in the duodenal bulb in 13%. In a further 15% and 17.4% of cases, Crohn's disease of the duodenum and duodenal bulb, respectively, was suspected. The positive predictive value of focal gastritis in patients undergoing upper endoscopy and not yet known to have Crohn's disease is as high as 94%. Thus, a high proportion of Crohn's disease patients show upper gastrointestinal tract involvement, with the major involvement in the antrum. Focal gastritis suggesting Crohn's disease turned out to have a high positive predictive value in patients not known to have Crohn's disease at the time of gastroscopy.

[Psychoanalytic therapy of sexually abused adolescents]

Sexual abuse as an extreme childhood trauma produces distorted object-images, introjects of violence which reproduce the trauma permanently through symptoms and acting-out. Although the traumatic power should be relived in transference, psychoanalytic therapy does not always mean permanent interpretation of transference, rather supporting, confirming, valuing activity is indicated. The following scopes can be differentiated: idealization, changing the therapeutic object into a triangulating one; negative transference of an archaic destructive mother imago, nevertheless also of the traumatic object, setting free hidden aggressive affects; emerging of the specific sexual trauma in transference and counter-transference. In the whole course of therapy, especially at the end, working through of guilt-feelings, shame and mourning permits the separation from the traumatic objects, although the danger of returning to them, often represented by the real actual objects, does not guarantee a full success in all cases.

[2 forms of identification with the aggressor--according to Ferenczi and Anna Freud]

Severe traumatic aggression in the intrafamilial development, as in political persecution, torture and concentration camp terror, can be psychically coped with the identificatory acception of and submission to the overwhelming power. FERENCZI first described this mechanism as a result of sexual abuse, physical mistreatment and the terrorism of chronically ill parents against their children. The victim introjects the terror, identifies himself with it and so remains victim throughout his life by repetition compulsion. ANNA FREUD has used the term 'identification with the aggressor' in the case of children showing more ego-strength, which are able to defend aggressively a feared attack by identification with it. FERENCZIS discoveries signify an important extension of psychoanalytic theory especially for the understanding of severe personality disorders and the internalization process of traumatic power.

Amino acid sequence determinants of beta-lactamase structure and activity

TEM-1 beta-lactamase catalyzes the hydrolysis of beta-lactam antibiotics such as the penicillins and cephalosporins, thus providing for bacterial resistance to these compounds. To determine the amino acid residues critical for the structure and function of TEM-1 beta-lactamase, the codons for each of the 263 amino acid residues that constitute the mature form of the enzyme were randomized using a site-directed mutagenesis procedure. Functional random mutants were selected based on their ability to confer ampicillin resistance to Escherichia coli. The DNA sequence of several functional mutants was determined for each set of random mutants. It was found that 43 out of the 263 amino acid residues do not tolerate substitutions and therefore are critical for the structure and activity of the enzyme. In addition, a comparison of conserved residue positions among functional beta-lactamase mutants with conserved residues in the beta-lactamase gene family identified many positions which did not tolerate substitutions in the mutagenesis studies but are freely substituted among members of the gene family. This observation may be due to the accumulation of compensating mutations among members of the gene family. Finally, the sequence variability at residue positions among functional mutants was quantitated by calculating the effective number of substitutions at each position using information-theoretical entropy. These values were used to obtain a quantitative estimate of the correlation between the sequence variability at a position and the fractional accessible surface area of the residue. The correlation is found to be statistically significant in that buried residues tend to exhibit low variability and invariant residues tend to exhibit low solvent exposure. However, the correlation is weak because most residues are neither completely buried nor invariant.

Dibutyryl cyclic adenosine monophosphate and forskolin alter the paracellular pathway in cultured corneal endothelial cells

PURPOSE

This study describes the effects of the cyclic adenosine monophosphate (cAMP) pathway on the tight junctional barrier of the corneal endothelium, which plays a critical role in maintaining the corneal stroma in an underhydrated, transparent state.

METHODS

Subcultured bovine corneal endothelial cells grown on filters were used to study the effects of dibutyryl-cAMP and forskolin on transendothelial electrical resistance and [3H]inulin flux. The tight junction-associated protein ZO-1 (zonula occludens protein-1) and F-actin were visualized by indirect immunofluorescence, and the ultrastructural organization of junctional complexes was studied by freeze-fracture electron microscopy.

RESULTS

Cells formed a continuous monolayer of closely apposed hexagonal-type cells separated by a discontinuous belt of tight junctions with a transendothelial electrical resistance of 20.8 +/- 0.6 omega.cm2. Dibutyryl-cAMP (10(-4) M) and forskolin (10(-5) M) increased cell cAMP, significantly decreased the transendothelial resistance by 54% and 43%, respectively, and increased the flux of [3H]inulin from the apical to the basal side of the cells by 56% and 40%, respectively. Both agents also induced condensation of F-actin at the cell borders without any marked changes in the immunostaining of ZO-1 that delineated cell peripheries. However, freeze-fracture studies showed that dibutyryl-cAMP and forskolin induced dispersion of the tight junction network.

CONCLUSIONS

These data suggest that activation of the cAMP-dependent pathway, leading to structural changes of the tight junctional network, may modulate the passive fluxes mediated by the paracellular pathway of the corneal endothelial barrier.