Thrombotic thrombocytopenic purpura associated with HIV and visceral Kaposi's sarcoma treated with plasmapheresis and chemotherapy

We present a case of a patient who is HIV positive and developed both thrombotic thrombocytopenia purpura and visceral Kaposi's sarcoma (KS) with hemorrhage. This case presents a difficult management problem in that the patient's bleeding originated from KS lesions and did not quickly abate with plasmapheresis therapy despite both clinical and laboratory improvement after 2-4 days. Chemotherapy was initiated on day 13 and the patient's condition improved markedly afterward. We believe the addition of chemotherapy to plasmapheresis hastened the improvement of our patient's thrombotic thrombocytopenic purpura (TTP) and KS-related bleeding. Therefore, under similar conditions, we recommend combining plasmapheresis and chemotherapy at the onset of therapy.

Do not resuscitate orders--managing the dilemma

The status of DNR orders (or equivalent declarations) in patients undergoing surgery will continue to present considerable challenges for both healthcare providers and patients, or their alternate decision makers. It is essential that all parties understand the specifics of each DNR order, focusing not only on the actual content of the order or declaration but also on the context in terms of location, timing and circumstance. The principle of "respect for persons" should guide, inform and shape the approach followed with each patient. Meaningful dialogue and "negotiation" will be required. Make no assumptions! The "required reconsideration" of pre-existing DNR orders should be the basic approach followed. There is no single "solution" for all DNR-related issues in the peri-operative period. What may appear obvious to the anaesthetist may be viewed entirely differently by the patient, or even by other members of the care giving team. There is no justification for either the automatic suspension or the automatic continuation of DNR orders in patients undergoing surgery. A patient-specific and situation-specific approach and "solution" is required. Similar principles will apply in acute care settings other than the operating room. Full engagement by health care workers in the processes addressing these issues should be a personally enriching experience.

Escherichia coli β-galactosidase is heterogeneous with respect to the activity of individual molecules

Escherichia coli β-galactosidase molecules were incubated with fluorogenic substrate in a capillary. Upon flushing the reactor contents past the detector, individual randomly distributed peaks of product were observed, each representing the activity of an individual enzyme molecule. Individual molecules were found to differ with respect to their activities. Molecules showed a 23-fold distribution of activities with the majority of molecules within a 4-fold distribution.Key words: single-molecule chemistry, β-galactosidase, capillary electrophoresis, laser-induced fluorescence, enzyme assay.

Once weekly azithromycin therapy for prevention of Mycobacterium avium complex infection in patients with AIDS: a randomized, double-blind, placebo-controlled multicenter trial

We conducted a randomized, double-blind, placebo-controlled multicenter trial of azithromycin (1,200 mg once weekly) for the prevention of Mycobacterium avium complex (MAC) infection in patients with AIDS and a CD4 cell count of < 100/mm3. In an intent-to-treat analysis through the end of therapy plus 30 days, nine (10.6%) of 85 azithromycin recipients and 22 (24.7%) of 89 placebo recipients developed MAC infection (hazard ratio, 0.34; P = .004). There was no difference in the ranges of minimal inhibitory concentrations of either clarithromycin or azithromycin for the five breakthrough (first) MAC isolates from the azithromycin group and the 18 breakthrough MAC isolates from the placebo group. Of the 76 patients who died during the study, four (10.5%) of 38 azithromycin recipients and 12 (31.6%) of 38 placebo recipients had a MAC infection followed by death (P = .025). For deaths due to all causes, there was no difference in time to death or number of deaths between the two groups. Episodes of non-MAC bacterial infection per 100 patient years occurred in 43 azithromycin recipients and 88 placebo recipients (relative risk, 0.49; 95% confidence interval, 0.33-0.73). The most common toxic effect noted during the study was gastrointestinal, reported by 78.9% of azithromycin recipients and 27.5% of placebo recipients. Azithromycin given once weekly is safe and effective in preventing disseminated MAC infection, death due to MAC infection, and respiratory tract infections in patients with AIDS and CD4 cell counts of < 100/mm3.

Detection of Aequorea victoria green fluorescent protein by capillary electrophoresis laser induced fluorescence detection

Aequorea victoria green fluorescent protein was assayed by capillary electrophoresis using post-capillary laser-induced fluorescence detection in a sheath flow cuvette. The limit of detection was 3.0 x 10(-12) M protein in an injection volume of 17 nL, corresponding to a mass of 3100 molecules.

Do not resuscitate orders in the operating room

PURPOSE

The background to a current analysis of the management of "do not resuscitate" (DNR) orders in the operating room is reviewed, with an emphasis on the current status of resuscitation/DNR issues in Canada.

SOURCE

The Joint Statement on Resuscitative Interventions published by the Canadian Medical Association and cooperating organizations and the report of the Senate of Canada Special Committee on Euthanasia and Assisted Suicide are examined for information relevant to the DNR issue. Guidelines on the management of DNR orders in the operating room, published by the American Society of Anesthesiologists and the American College of Surgeons are used to provide a perioperative DNR order management approach consistent with the Joint Statement on Resuscitative Interventions.

PRINCIPAL FINDINGS AND CONCLUSIONS

The dominant principle is that of the patient's right to self determination. This right can be exercised either directly by the patient, or through an appropriate alternate, or in the form of an advance directive. DNR orders are not incompatible with subsequent surgical care in an operating room. It is wrong to suspend automatically DNR orders in the perioperative period. It is wrong to continue DNR orders automatically in the perioperative period. It is wrong to make assumptions about the meaning of an individual DNR order. An appropriate approach to the perioperative management of pre-existing DNR orders is one based on "required reconsideration." All anaesthetists must be aware of their responsibilities in managing patients with DNR orders in place.

Studies of 8-azido-ATP adducts reveal two mechanisms by which ATP binding to cytochrome c could inhibit respiration

We have proposed that the binding of ATP at a site of substantial affinity and specificity could regulate the activity of cytochrome c with its physiological partners and thus the overall efficiency of mitochondrial electron transport. We now describe the use of ATP affinity-labeled protein to test the effect of occupancy of that site, which includes the invariant arginine 91, on the activity of cytochrome c with purified cytochrome c reductase and oxidase and its association with the mitochondrial inner membrane. Electron-transfer activities with the reductase and oxidase were inhibited by site occupancy to 41% and 11-15% of native values, respectively. The marked difference in the degree of inhibition of activity that distinguishes the reactions with the two major physiological partners was sufficient to cause, in whole mitochondria, a demonstrable shift from a situation in which there is a rate-limiting transfer from the reductase to cytochrome c, to a state where rates are more evenly matched for transfers between cytochrome c and the two redox partners. Site occupancy also substantially reduces the ionic strength necessary for half-maximal dissociation of cytochrome c from the membrane. These data imply that the decreased efficiency of electron transfer caused by ATP attachment can be attributed to a decrease in the protein's activity with individual physiological partners, possibly compounded with a decrease in its affinity for the inner mitochondrial membrane, and suggest that feedback regulation by ATP of cellular respiration operates in like manner.

ATP binding to cytochrome c diminishes electron flow in the mitochondrial respiratory pathway

Eukaryotic cytochrome c possesses an ATP-binding site of substantial specificity and high affinity that is conserved between highly divergent species and which includes the invariant residue arginine91. Such evolutionary conservatism strongly suggests a physiological role for ATP binding that demands further investigation. We report the preparation of adducts of the protein and the affinity labels 8-azido adenosine 5'-triphosphate, adenosine 5'-triphosphate-2',3'-dialdehyde, and 5'-p-fluorosulfonylbenzoyladenosine. The two former reagents were seen to react at the arginine91-containing site, yet the reaction of the latter, although specific, occurred elsewhere, suggesting caution is necessary in its use. None of the adducts displayed significant modification of global structure, stability, or physicochemical properties, leading us to believe that the 8-N3-ATP and oATP adducts are good stabilized models of the noncovalent interaction; yet modification led to significant, and sometimes pronounced, effects on biological activity. We therefore propose that the role of ATP binding to this site, which we have shown to occur when the phosphorylation potential of the system is high under the equivalent of physiological conditions, is to cause a decrease in electron flow through the mitochondrial electron transport chain. Differences in the degree of inhibition produced by differences in adduct chemistry suggest that this putative regulatory role is mediated primarily by electrostatic effects.

Correlation of oral disease with the Walter Reed staging scheme for HIV-1-seropositive patients

This study correlates the prevalent oral disease findings in 390 patients seropositive for human immunodeficiency virus type 1 (HIV-1) with their level of staging (Walter Reed) and depletion of peripheral helper T lymphocytes (CD4+). Chronic lymphadenopathy of the head and neck was a common finding (59.2%) that occurred early in staging progression and did not correlate with depression of helper T-cell levels. Of the three prevalent oral disease findings (oral hairy leukoplakia (OHL), candidiasis, necrotizing ulcerative gingivitis [NUG]) only OHL and NUG were significantly correlated with helper T-cell depletion. The occurrence of visually detectable OHL and NUG corresponds to depletion of peripheral helper T-lymphocyte values in a range of 157 to 299 cells/mm3. This range may represent a more accurate value for biologically significant lymphocyte depletion than the Walter Reed value of 400 cells/mm3. The presence of OHL showed a weak statistical correlation with staging progression, indicating deteriorating immunoregulation. No cases of Kaposi's sarcoma or other HIV-1-associated oral diseases were observed in the sample population, regardless of the patient's staging category or peripheral helper T-lymphocyte count.

The specificity and Kd at physiological ionic strength of an ATP-binding site on cytochrome c suit it to a regulatory role

Cytochrome c binds ATP with marked specificity at a site that contains the evolutionarily invariant residue Arg-91. The binding of ATP to this site was studied using equilibrium gel filtration, equilibrium dialysis and affinity chromatography. At physiological ionic strength the affinity is such that the major change in occupancy coincides with the normal cellular ATP concentration range, and the degree of saturation is proportional to the ratio of [ATP]/[ADP]. The specificity of binding at this site is more a function of the degree of phosphorylation of the nucleotide, than of the nature of the nucleoside moiety. Thus under physiological conditions the degree of occupancy of this site is proportional to the energy state of the cell, providing a means for the regulation of the respiratory chain which is sensitive to cytoplasmic ATP levels.

Melioidosis: a reminder

Recrudescent pulmonary melioidosis developed in two patients 12 and 16 years after their last travels to an endemic area. In one, a clinically silent prostatic abscess may have been the focus; and in both, the diagnosis was difficult to make even when the laboratory was notified of the possibility of infection with Pseudomonas pseudomallei. Recrudescent melioidosis should be considered in febrile patients who have been in endemic areas regardless of the interval from last exposure to the development of disease.

Comparison of bupivacaine and alkalinized bupivacaine in brachial plexus anesthesia

To define the effect of alkalinization of bupivacaine 0.5% in subclavian perivascular brachial plexus blockade, the time to onset, time to peak effect, and 6-hour regression of sensory and motor blockade were determined. Sixty physical status ASA I and II patients were randomly allocated to one of two groups and a double-blind design was used: group I (n = 30) received bupivacaine 0.5% (pH, 5.5) 3 mg/kg, while group II (n = 30) received alkalinized bupivacaine 0.5% (pH, 7.05-7.15) 3 mg/kg. Onset and regression of sensory blockade were determined by pinprick in the C4-T2 skin dermatomes, while motor blockade was assessed using a scheme of proximal to distal muscle group paralysis. Time to onset of sensory blockade (group I, 4.0 +/- 1.2 min; group II, 3.6 +/- 0.9 min) and time to peak sensory effect (group I, 17.7 +/- 1.8 min; group II, 16.3 +/- 1.8 min) did not differ significantly between the groups. Similarly, no difference in time to onset of motor blockade (group I, 6.9 +/- 1.7 min; group II, 6.3 +/- 1.5 min) or time to peak motor effect (group I, 18.1 +/- 1.9 min; group II, 15.1 +/- 1.9 min) was observed. Regression of postoperative sensory and motor blockade was similar in both groups. It is concluded that alkalinization of bupivacaine 0.5% solutions does not confer any added clinical advantage in subclavian perivascular brachial plexus blockade when compared with commercially available bupivacaine.