Mechanical ventilation in critically ill cancer patients

Outcomes for cancer patients undergoing mechanical ventilation have improved in recent times, and the outlook for this patient group is no longer hopeless. Advances in ventilation techniques and increasingly sophisticated equipment have allowed oncologic intensivists to intervene more effectively in their patients' critical illness. In addition, many of these patients are now referred for intensive care much earlier. This article reviews the use of mechanical ventilation in critically ill cancer patients and includes discussion of the recently published outcome literature. We also discuss some recent advances in the broader field of mechanical ventilation and demonstrate how these advances can be applied to the oncology population.

Occurrence of Burkholderia cepacia in foods and waters: clinical implications for patients with cystic fibrosis

Two hundred forty-eight retail "ready-to-eat" foodstuffs in eight food categories and 134 waters categorized into nine types were analyzed for the presence of the Burkholderia cepacia complex of organisms. Of these, 14 of 26 (53.8%) samples of raw unpasteurized bovine milk were positive for this organism. Consumption of raw unpasteurized milk may therefore act as a potential source of infection with this organism, which is of particular concern for patients with cystic fibrosis, where colonization and infection with this organism can lead to a fatal necrotizing pneumonia and premature death. In addition to the associated risk of infection from fecal pathogens, patients with cystic fibrosis should therefore avoid the consumption of raw unpasteurized milk to minimize the risk of becoming infected with this organism.

The X-ray crystal structure of the Trichoderma reesei family 12 endoglucanase 3, Cel12A, at 1.9 A resolution

We present the three-dimensional structure of Trichoderma reesei endoglucanase 3 (Cel12A), a small, 218 amino acid residue (24.5 kDa), neutral pI, glycoside hydrolase family 12 cellulase that lacks a cellulose-binding module. The structure has been determined using X-ray crystallography and refined to 1.9 A resolution. The asymmetric unit consists of six non-crystallographic symmetry-related molecules that were exploited to improve initial multiple isomorphous replacement phasing, and subsequent structure refinement. The enzyme contains one disulfide bridge and is glycosylated at Asp164 by a single N-acetyl glucosamine residue. The protein has the expected fold for a glycoside hydrolase clan-C family 12 enzyme. It contains two beta-sheets, of six and nine strands, packed on top of one another, and one alpha-helix. The concave surface of the nine-stranded beta-sheet forms a large substrate-binding groove in which the active-site residues are located. In the active site, we find a carboxylic acid trio, similar to that of glycoside hydrolase families 7 and 16. The strictly conserved Asp99 hydrogen bonds to the nucleophile, the invariant Glu116. The binding crevice is lined with both aromatic and polar amino acid side-chains which may play a role in substrate binding. The structure of the fungal family 12 enzyme presented here allows a complete structural characterization of the glycoside hydrolase-C clan.

Subclinical rejection--a potential surrogate marker for chronic rejection--may be diagnosed by protocol biopsy or urine spectroscopy

Our studies of protocol biopsy studies have shown that normal allograft histology can not be assumed by crude tests of renal function such as the serum creatinine concentration, and that there is a high prevalence of subclinical rejection in the first 6 months post-transplant (7, 13-17). The apparent ability of urine MR and IR spectra to reliably identify patients with normal allograft histology, if confirmed in a larger database, will preclude the need for a protocol biopsy in approximately 20-50% of patients. Conversely, finding urine MR or IR spectra characteristic of subclinical rejection would provide the opportunity for early treatment. The clear separation between patients with normal histology from those with subclinical rejection can be attributed to the use of the whole urine spectrum to develop the classifiers. Additional advantages of using MR or IR spectra of urine as a diagnostic tool compared to the biopsy include simplicity (i.e. no processing is required), low cost, rapid turnaround (i.e. < 15 minutes/sample), and, particularly, low risk, thus allowing for repetitive sampling. The ability to non-invasively diagnose acute inflammation in the kidney would be of great assistance in the post-transplant monitoring of renal transplant patients. Indeed, by following subclinical inflammation as detected in the MR/IR spectra it will be possible to tailor the intensity of the immunosuppression to the inflammatory status of the graft, thus minimising the risks of both insufficient and excessive immunosuppression. Furthermore, by following subclinical inflammation, as detected in the MR/IR spectra, it will be possible to test the hypothesis that subclinical rejection (i.e. persistence of its MR/IR spectral classifier) is a surrogate marker for the development of chronic rejection.

Role of P glycoprotein in the course and treatment of Encephalitozoon microsporidiosis

Encephalitozoon microsporidia are obligate intracellular protozoan parasites that proliferate and differentiate within a parasitophorous vacuole inside host cells that are usually epithelial in nature. Isolates of the three species of the Encephalitozoon microsporidia, E. cuniculi, E. hellem, and E. intestinalis, were obtained from AIDS patients and cultured in green monkey (E6) kidney cells. Anti-P-glycoprotein (anti-Pgp) and anti-multidrug resistance-associated protein (anti-MRP) monoclonal antibodies were used to probe for multidrug resistance (MDR) pump epitopes and verapamil- or cyclosporin A- and probenecid-modulated intracellular calcein fluorescence were used to assess the expression of Pgp and MRP respectively in uninfected and infected cells. Pgp, but not MRP, was detected immunocytochemically and by verapamil- and cyclosporin A-potentiated intracellular fluorescence in both host cells and parasite developing stages. When an in vitro infection assay was employed, verapamil and cyclosporin A acted as chemosensitizing agents for the antiparasitic drug albendazole. These observations suggest that inhibiting host cell and perhaps parasite MDR pumps may increase the efficacy of antiparasitic agents in these and other microsporidia species.

Structure of the AAA ATPase p97

p97, an abundant hexameric ATPase of the AAA family, is involved in homotypic membrane fusion. It is thought to disassemble SNARE complexes formed during the process of membrane fusion. Here, we report two structures: a crystal structure of the N-terminal and D1 ATPase domains of murine p97 at 2.9 A resolution, and a cryoelectron microscopy structure of full-length rat p97 at 18 A resolution. Together, these structures show that the D1 and D2 hexamers pack in a tail-to-tail arrangement, and that the N domain is flexible. A comparison with NSF D2 (ATP complex) reveals possible conformational changes induced by ATP hydrolysis. Given the D1 and D2 packing arrangement, we propose a ratchet mechanism for p97 during its ATP hydrolysis cycle.

The discovery of non-basic atrial natriuretic peptide clearance receptor antagonists. Part 1

The cyclic peptide ANP 4-23 and the linear peptide analogue AP-811 have been shown to be selective ANP-CR antagonists. Via alanine scanning and truncation studies we sought to determine which residues in these molecules were important in their binding to the clearance receptor and the relationship between these two molecules. These studies show that several modifications to these compounds are possible which improve physical properties of these molecules while retaining high affinity for the ANP-CR.

Treatment decisions for newborns at the threshold of viability: an ethical dilemma

The major ethical issues involved in decision-making in the care of extremely low birth weight newborns are analyzed here. We propose a schema for assessment and management of these infants that is consistent with ethical principles broadly accepted by the pediatric community, and which takes into account mortality risk at any given institution rather than arbitrary weight limits, with a major decision-making role for the infant's parents. When possible, the decision of whether or not to resuscitate should be made before delivery; when not possible, delivery room resuscitation is recommended, and the decision to continue or withdraw care should be made subsequently based on likelihood of survival and the wishes of the parents.

Efficacy of a nelfinavir- and nevirapine-containing salvage regimen

PURPOSE

In this study, our purpose was to assess the efficacy of nelfinavir- and nevirapine-containing salvage regimens in nonnucleoside reverse transcriptase inhibitor (NNRTI)-naive patients virologically failing a protease inhibitor (PI)-based combination.

METHOD

A retrospective case note review of all patients virologically failing their PI-based combination who were switched to a regimen containing both nelfinavir (1 g t.d.s.) and nevirapine (200 mg b.d.). CD4 cell counts and viral loads were monitored. Genotypic analysis was performed using RT-PCR sequencing.

RESULTS

Nineteen patients commenced a salvage regimen containing nelfinavir and nevirapine. Five patients also changed at least one nucleoside reverse transcriptase inhibitor (NRTI), although in one case this represented recycling. Thirty-eight percent (6/16) of patients achieved a viral load below the level of detection (BLD; <200 copies/mL; complete responders [CR]), 3 achieved <20 copies/mL. Five patients achieved > or =1 log drop (partial responders [PR]) that was not sustained over follow-up, and five failed to respond to therapy (nonresponders [NR]). CRs tended to have wild-type NNRTI and PI sequences relative to PRs and NRs.

CONCLUSION

In heavily pretreated patients, a nelfinavir-and nevirapine-containing salvage regimen resulted in a virological response in 38% of patients that was sustained in 31% over 63 weeks.

The Ponzo illusion affects grip-force but not grip-aperture scaling during prehension movements

Contextual cues such as linear perspective and relative size can exert a powerful effect on the perception of objects. This fact is demonstrated by the illusory effects that can be induced by such cues (e.g., the Ponzo railway track and Titchener circles illusions). Several recent studies have reported, however, that visual illusions based on such cues have little or no influence on the visuomotor mechanisms used to guide hand action. Furthermore, evidence of this sort has been cited in support of a distinction between visual perception and the visual control of action. In the current study, the authors investigated the effect of the Ponzo visual illusion on the control of hand action, specifically, the scaling of grip force and grip aperture during prehension movements. The results demonstrate that grip force scaling is significantly influenced by the Ponzo visual illusion, whereas the scaling of grip aperture is unaffected by the illusion.

The Ponzo illusion affects grip-force but not grip-aperture scaling during prehension movements

Contextual cues such as linear perspective and relative size can exert a powerful effect on the perception of objects. This fact is demonstrated by the illusory effects that can be induced by such cues (e.g., the Ponzo railway track and Titchener circles illusions). Several recent studies have reported, however, that visual illusions based on such cues have little or no influence on the visuomotor mechanisms used to guide hand action. Furthermore, evidence of this sort has been cited in support of a distinction between visual perception and the visual control of action. In the current study, the authors investigated the effect of the Ponzo visual illusion on the control of hand action, specifically, the scaling of grip force and grip aperture during prehension movements. The results demonstrate that grip force scaling is significantly influenced by the Ponzo visual illusion, whereas the scaling of grip aperture is unaffected by the illusion.

The use of electronic mail in biomedical communication

OBJECTIVES

To determine whether there are statistically significant differences in the content of electronic mail (e-mail) and conventional mail sent to authors of papers published in medical journals.

DESIGN

Prospective study by postal questionnaire. Over two one-month periods, corresponding authors of papers published in medical journals were asked to record details of the correspondence prompted by their publications.

MEASUREMENTS

Conventional and e-mail correspondence received. Reprint requests. Content of correspondence. Quality of correspondence.

RESULTS

Eighty-two of 96 authors replied. Fifty received e-mail (mean, 5.7+/-8.8 e-mails per author) and 72 received conventional mail (15.5+/-32.8 letters per author) (p < 0.05). Seventy percent of e-mails and only 53% of correspondence sent by conventional mail (p < 0.05) referred to the content of the paper.

CONCLUSIONS

Publication in general medical journals stimulates more conventional than electronic mail. However, the content of e-mail may be of greater scientific relevance. Electronic mail can be encouraged without fear of diminishing the quality of the communications received.