Hydroxyurea-induced hypersensitivity pneumonitis: A case report and literature review

Hydroxyurea is a cytotoxic agent indicated in the treatment of a variety of malignant and nonmalignant conditions. Apart from dose-related bone marrow suppression, this antineoplastic agent is generally well tolerated. This report describes a patient with chronic myeloid leukemia who developed severe pneumonitis within four weeks of beginning therapy with hydroxyurea. Pathological examination of a lung specimen obtained by video-assisted thoracoscopic lung biopsy revealed extensive active alveolar and interstitial inflammation, and poorly formed granulomas. After the cessation of hydroxyurea and treatment with systemic corticosteroids, both clinical and radiological resolution of pneumonitis occurred. Physicians using hydroxyurea must be aware of its potentially life-threatening pulmonary toxicity.

[Pivotal role of axonal adhesion molecules in central nervous system myelination]

Close relationship between neurons and oligodendrocytes seems to be of the greatest importance during oligodendrocyte maturation and myelin formation within central nervous system. Two major factors are likely to play the decisive role in CNS myelination--adhesion molecules and electrical activity. It has been shown, both in vitro and in vivo, that blocking or stimulating electrical activity may inhibit or induce myelination respectively. The fact that even in culture oligodendrocytes myelinate solely axons and not other cellular processes present within CNS as well as the finding that normal myelin sheath compaction is encountered only around axons suggest that close interaction between oligodendrocytes and neurons is required for normal myelin formation. Adhesion molecules are most likely involved in this interaction by not only bringing the axon and the glial cell close to each other but also by transducing signals to initiate myelination. The neural cell adhesion molecule (NCAM) is a candidate molecule that could regulate axon/glial cell interaction. It is abundantly present in all growing fiber tracts of the developing CNS. Since its polysialylated from (PSA-NCAM) has been shown to disappear from axonal surface as myelination progresses and that its removal increases 4 to 5 fold myelination, it is thought to be a negative factor for myelin formation. These observations may have important implications in therapeutic strategies in demyelinating disorders like multiple sclerosis.

Influence of tumor localization on the prognostic value of P53 protein in colorectal adenocarcinomas

BACKGROUND

The prevalence of genetic alterations is different in primary carcinomas from the proximal colon when compared with carcinomas from the distal colorectum. The objective of this work was to explore the existence of possible differences in the informative weight of the risk of tumor recurrence provided by p53 immunostaining depending on the localization of the neoplasm.

PATIENTS AND METHODS

Nuclear immunohistochemical expression of p53 protein was determined in formalin-fixed paraffin-embedded archival tumor tissue samples from 190 primary colorectal adenocarcinomas. The relative prognostic importance on the risk of recurrence of each variable was assessed in a Cox's proportional hazard regression analysis. Multiplicative interaction terms between p53 and tumor site were included in the multivariate models in order to test their joint effect on survival.

RESULTS

One hundred and one patients (53.1%) manifested nuclear accumulation of the protein. P53 overexpression was more frequent in distal than in proximal tumors (58.5% ve s 41.7%) (p = 0.03). Disease-free survival was lower in p53-positive cases (75% versus 38%) (p = 0.006), but significance of the association varied according to the localization of the tumor (p = 0.004 in proximal carcinomas and p = 0.049 in distal carcinomas). Multivariate analysis identified p53 positivity and distal tumor localization as the factors significantly associated with a high risk of recurrence Interaction between p53 expression and localization was present. P53 exhibited different prognostic value in distal and proximal colon. While adjusted hazard ratio for positive p53 was 1.99 in distal cancers, it was 8.04 for proximal tumors.

CONCLUSION

The prognostic with value of tumor recurrence associated overexpression of p53 protein is influenced by the location of the tumor. The negative predictive weight is significantly higher in proximal than in distal cancers.

IL-2 plasmid therapy of murine ovarian carcinoma inhibits the growth of tumor ascites and alters its cytokine profile

We have evaluated whether i.p. murine ovarian tumors could be treated with an IL-2 plasmid DNA complexed with the cationic lipid, (+/-)-N-(2-hydroxyethyl)-N,N-dimethyl-2, 3-bis(tetradecyloxy)-1-propanaminium bromide/dioleoylphosphatidylethanolamine (DMRIE/DOPE). Reporter gene studies were initially conducted in which mice bearing i.p. murine ovarian teratocarcinoma (MOT) were injected i.p. with reporter gene plasmid DNA (pDNA):DMRIE/DOPE. Histochemical analyses revealed that transfection occurred primarily in the tumor cells of the ascites, with only a minority of other ascitic cells or surrounding tissues transfected. IL-2 levels in the MOT ascites were determined after i. p. injection of either IL-2 pDNA:DMRIE/DOPE or recombinant IL-2 protein. IL-2 was detected in tumor ascites for up to 10 days after a single i.p. injection of IL-2 pDNA:DMRIE/DOPE, but was undetectable 24 h after a single i.p. injection of IL-2 protein. In an antitumor efficacy study, MOT tumor-bearing mice injected i.p. with IL-2 pDNA:DMRIE/DOPE on days 5, 8, and 11 after tumor cell implant had a significant inhibition of tumor ascites (p = 0.001) as well as a significant increase in survival (p = 0.008). A cytokine profile of the MOT tumor ascites revealed that mice treated with IL-2 pDNA:DMRIE/DOPE had an IL-2-specific increase in the levels of IFN-gamma and GM-CSF. Taken together, these findings indicate that i. p. treatment of ovarian tumors with IL-2 pDNA:DMRIE/DOPE can lead to an increase in local IL-2 levels, a change in the cytokine profile of the tumor ascites, and a significant antitumor effect.

Cartilage and serum levels of nitric oxide in patients with hip osteoarthritis

OBJECTIVE

To assess whether nitric oxide (NO) is related to cartilage deterioration resulting from osteoarthritis, NO concentrations were analyzed in normal and deteriorated areas of cartilage obtained from femur heads of patients with primary hip osteoarthritis (HOA).

METHODS

The concentration of NO in macroscopically deteriorated and non-deteriorated cartilage of femoral heads of patients with HOA at hip replacement surgery was analyzed spectrophotometrically. Serum NO levels were also determined in 16 ambulatory patients with hip OA and in healthy volunteers.

RESULTS

NO levels of non-deteriorated areas of femoral head cartilage were significantly lower (3.82+/-1.30 micromol/l; mean +/- SD) than levels of deteriorated cartilage areas (11.07+/-6.48 micromol/l; p<0.01). The surgery HOA group showed serum NO levels (2.64+/-0.32 micromol/l; p<0.0001 vs. healthy group) similar to the ambulatory HOA group levels (2.56+/-0.56 micromol/l; p<0.0001 vs. healthy group). Serum NO concentrations in healthy volunteers were 1.37+/-0.55 micromol/l.

CONCLUSION

This study shows increased NO levels in joint cartilage of patients with hip OA. This increase was not homogeneously distributed, but the higher NO levels were found in macroscopically deteriorated areas. The data also suggest that high NO serum levels found in patients with hip OA may be due to joint cartilage destruction.

Antitumor effects of interferon-omega: in vivo therapy of human tumor xenografts in nude mice

The antitumor effect of the type I IFN, IFN-omega, was evaluated in both in vitro and in vivo studies of human cancer. For these studies, the cDNA for human IFN-omega was cloned into a eukaryotic expression plasmid DNA (pDNA) driven by the cytomegalovirus promoter. Supernatants from UM449 cells transfected in vitro with IFN-omega pDNA had antiproliferative effects on 11 of 13 human tumor cell lines. For in vivo studies, nude mice were implanted s.c. with one of the following human tumors: NIH: OVCAR-3 ovarian carcinoma, A375 melanoma, or A431 epidermoid carcinoma. Direct intratumoral injection of 100 microg of a IFN-omega pDNA DMRIE/DOPE complex (1:1 DNA:DMRIE mass ratio) for 6 consecutive days resulted in a significant reduction in the tumor volume of NIH: OVCAR-3 ovarian carcinoma or A375 melanoma (P = 0.02). IFN-omega pDNA delivered by i.m. injection also had an antitumor effect. Nude mice bearing s.c. A431 epidermoid carcinoma and injected i.m. with 100 microg of IFN-omega pDNA, twice per week for 3 weeks, had a significant reduction in tumor volume (P = 0.009). These results demonstrate for the first time that IFN-omega can have in vivo antitumor effects in several models of human cancer.

Development of a blocking ELISA for screening antibodies to porcine rubulavirus, La Piedad Michoacan Virus

A blocking enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies to porcine rubulavirus (La Piedad Michoacan Virus [LPMV]) in serum samples from pigs. The test, based on a monoclonal antibody against the LPMV hemagglutinin-neuraminidase glycoprotein, had a sensitivity of 99% and a specificity of 97%. The results of this test were in agreement with those obtained by an indirect ELISA and hemagglutination inhibition, indirect immunofluorescence, and virus neutralization tests. The blocking ELISA is considered the most suitable test for routine screening for antibodies against LPMV.

Biochemistry and pharmacology of rabbit cardiac growth hormone (GH) receptors

In this report we present the first in-depth description of the biochemical and pharmacological properties of rabbit cardiac GH receptors. The apparent M(r)'s of the [125I]human (h) GH-receptor complexes were 380, 205, 90, 62, 52 and 38 kDa as demonstrated by an autoradiograph of affinity-labelled cardiac GH receptors separated under non-reducing conditions by SDS PAGE. The [125I]hGH-cardiac GH receptor complexes were disulfide-linked since the M(r)s of the complexes diminished to 170, 116, 97, 71, 45 and 38 kDa under reducing conditions, indicating the presence of multiple receptors, receptor-associated macromolecules or receptor and ligand in various ratios. The pharmacology of cardiac GH receptors is not typical of GH receptors present in other tissues. In radio receptor assays, both bovine GH and ovine prolactin were 50-fold and 100-fold less potent, respectively, than unlabelled hGH, in blocking the binding of [125I]hGH to cardiac binding sites and were, therefore, extremely weak antagonists. Similarly, neither bovine GH nor ovine prolactin blocked the [125I]hGH affinity-labelling of cardiac GH receptors compared to equivalent doses of unlabelled hGH. Parameters which characterize the kinetics for the association, dissociation and equilibrium binding of [125I]hGH to cardiac GH receptors were ascertained. Association kinetics for the binding of [125I]hGH to heart GH receptors exhibited a maximum specific binding at 17 h and 25 degrees C. The association of [125I]hGH to heart GH receptors was reversible with approximately 15 h required for half of the specifically bound [125I]hGH to dissociate. The coupling of [125I]hGH to heart GH receptors was optimum at pH 6 and the strength of the equilibrium binding, as measured by the ED50, was approximately 2 ng/ml. These data indicate that the cardiac GH receptors are pharmacologically distinct and that there is a M(r) heterogeneity in the [125I]hGH receptor complexes.

A gene therapy for cancer using intramuscular injection of plasmid DNA encoding interferon alpha

A cancer treatment is described in which i.m. injection of plasmid DNA (pDNA) encoding murine interferon alpha (mIFN-alpha) leads to potent antitumor effects on primary and metastatic tumors in mice. Mice bearing s.c. B16F10 melanoma, Cloudman melanoma, or glioma 261 tumors were injected i.m. with mIFN-alpha pDNA. In all three tumor models, a significant reduction in tumor volume and enhancement of survival was found after IFN pDNA therapy. The mIFN-alpha pDNA could be injected as infrequently as once every other week and still produce a significant antitumor effect, and, in a metastatic tumor model, the therapy markedly reduced the number of lung tumor metastases. Depletion of immune cell subsets indicated that CD8(+) T cells were required for the antitumor response. These studies demonstrate that primary and metastatic tumors can be treated systemically by i.m. injection of a plasmid encoding a cytokine gene.

Antiproliferative effects of N1,N4-dibenzylputrescine in human and rodent tumor cells

Polyamines (putrescine, spermidine and spermine) increase in proliferating tissues and are essential for cellular growth and cell division processes. We had previously shown that alkyl substituted putrescines can inhibit cell proliferation. We now tested the effects of the (N(alpha),N(omega)-dibenzyl derivatives of the simple diamines putrescine, cadaverine and 1,3-diaminopropane on the growth of three human squamous cell carcinoma (SCC) lines and a rat hepatoma (H-4-II-E) cell line. Survival assays were measured by treating exponentially-growing SCC cultures with N1,N4-dibenzylputrescine (DBP) (270 microM) or a rat hepatoma cell culture with DBP (100 microM) for 48 hrs. Inhibition of cell growth was measured either by the colony forming assay or by cell counting. DBP inhibited proliferation of the rat hepatoma (H-4-II-E) cell line and induced cytotoxicity when used at a concentration of 100 microM for >48 hrs. N1,N5-dibenzylcadaverine (DBC) also induced cytotoxicity at a similar concentration, while N1,N3-dibenzyl-1,3-diaminopropane (DBPr) was a much weaker inhibitor of cell growth. Inhibition of cell growth by DBP resulted in marked modifications of cell morphology, such as vacuole formation, decrease in size, pycnosis, change in staining behavior toward trypan blue and lack of adherence. DBP was also growth inhibitory in the three human SCC cell lines tested. The concentration of DBP required to achieve growth inhibition of SCC cells could be dramatically decreased in the presence of N1,N4-bis(buta-2,3-dienyl)butanediamine, a specific inhibitor of polyamine oxidase (PAOI). Moreover, although the presence of PAOI only prevented the oxidation (debenzylation) of approximately 20% of intracellular DBP over a 5-day period, it produced a 5-fold increase in the inhibition of cell proliferation by DBP. DBP (and DBC) inhibited putrescine uptake by rat hepatoma (H-4-II-E) cells in what appears to be a competitive reaction. A tenfold excess of putrescine over DBP did not inhibit the antiproliferative or cytotoxic effects of the latter. DBP administered for 72 hrs. depleted intracellular levels of putrescine, spermidine and spermine in the SCC lines by 50-100% of control values. It was found that DBP inhibited nucleic acid and protein synthesis at an early stage of cell proliferation, hence its growth inhibitory effect may be related to inhibition of the synthesis of macromolecules.

Tenidap decreases IL-8 and monocyte chemotactic peptide-1 (MCP-1) mRNA expression in the synovial tissue of rabbits with antigen arthritis and in cultured synovial cells

Since IL-8 and MCP-1 are chemoattractant proteins that participate in the recruitment of inflammatory cells into the arthritic joint, we examined the effects of tenidap, a new anti-inflammatory drug of the oxindole family, on IL-8 and MCP-1 expression in the joints of rabbits with acute antigen arthritis. The model was induced by injecting 5 mg/ml ovalbumin into the knees of 20 preimmunized rabbits. Animals were randomized into two groups: treated with tenidap (15 mg/kg per 12 h), or untreated. The effect of tenidap treatment was evaluated on chemokine production in synovial membranes of rabbits with arthritis and in cultured monocytic and synovial cells (SC). By immunoperoxidase staining, chemokines were localized in the synovial tissue. Chemokine messenger RNA levels in the synovial membranes and in cultured cells were analysed by reverse transcription-polymerase chain reaction (RT-PCR). At the end of the study, tenidap significantly reduced neutrophil infiltration into the joint cavity (27+/-4 x 10(6) cells/ml versus 45+/-6 x 10(6) cells/ml in untreated; P<0.05), and synovial effusion (134+/-15 microl versus 236+/-19 microl in untreated; P<0.005). Untreated rabbits showed synovial membrane up-regulation in mRNA expression of IL-8 and MCP-1 (11- and seven-fold versus healthy rabbits, respectively) that was markedly decreased by tenidap (two- and three-fold versus healthy rabbits, respectively). IL-8 and MCP-1 were localized in the synovial tissue in a perivascular pattern and areas of the interstitium and lining, mostly coinciding with cell infiltration. Tenidap also reduced the accumulation of IL-8 and MCP-1 proteins. In cultured synovial and monocytic cells, tumour necrosis factor-alpha (TNF-alpha) elicited an increase in gene expression of IL-8 (four- and nine-fold, respectively) and MCP-1 (nine- and four-fold, respectively) that was significantly reversed in both cell types by 10 microM tenidap. These results suggest that the beneficial effect of tenidap in acute antigen arthritis could be related to the down-regulation in gene expression and synthesis of IL-8 and MCP-1, two key chemokines involved in the recruitment of inflammatory cells.

A comparative study on the use of virus and antibody detection techniques for the diagnosis of La Piedad Michoacan paramyxovirus (LPMV) infection in pigs

La Piedad Michoacan paramyxovirus (LPMV) is newly recognized paramyxovirus that has been associated with neurologic and reproductive disorders in pigs in Mexico. To date, no comparative study of methods for the diagnosis of infection with this virus has been published. In this study, we identified tissues containing maximum virus load to optimize virus isolation procedures, and we compared this method to a rapid diagnostic test employing immunostaining of impression smears for LPMV antigens. In addition, several of the available tests for detecting LPMV antibodies were compared for their sensitivity in detecting seroconversion. Pigs used for the study of virus load in tissues and serologic studies were inoculated at 17 days of age with 10(7.00) TCID50 of LPMV. Serial blood samples were collected from selected pigs, and selected pigs were necropsied over a 14-day period. Pigs used in the investigation comparing standard virus isolation techniques to immunostaining of impression smears were inoculated at 3 days of age as described above and necropsied over an 8-day period. The results demonstrate that in the 17-day-old pigs maximum virus titers were detected in olfactory bulb at 5 days postinoculation (PI) and in midbrain at 9 days PI. In addition, the most consistent recovery of high titer virus was from tonsil (3-9 days PI) and olfactory bulb (4-9 days PI). Immunostaining of impression smears was as sensitive as virus isolation when selected tissues (lung, midbrain, olfactory bulb) were compared, with virus detected by both methods in 11/13 samples and in 1 sample each by immunostaining and virus isolation, respectively. All of the serology tests investigated detected seroconversion in pigs by 8 days PI. The identification of target organs where highest virus titers are found combined with immunofluorescent methods for the detection of LPMV antigens and a comparative study of the available serologic tests should facilitate the selection of techniques suitable for any laboratory to diagnose LPMV infection in pigs.

Proportional assist ventilation in acute respiratory failure: effects on breathing pattern and inspiratory effort

Proportional assist ventilation (PAV) is a new mode of assisted ventilation which, by applying pressure in proportion to volume (volume assist, VA) and flow (flow assist, FA), should specifically reduce the inspiratory effort needed to overcome respiratory system elastance (Ers) and resistance (Rrs), respectively. The aims of this study were to determine (1) the effects of varying the level of VA on breathing pattern, inspiratory effort, and work of breathing, and (2) the interaction between VA and FA. In eight intubated patients with acute respiratory failure, four levels of VA (20 to 80% Ers) with and without a fixed amount of FA (approximately 50% Rrs) were evaluated. Compared with spontaneous breathing, VA increased tidal volume (VT) while respiratory rate (RR) was unchanged or fell slightly. The increase in minute ventilation (VE) was small and not significant. The addition of FA further increased VT while RR was significantly reduced so that VE remained unchanged. Increasing VA produced a graded reduction in inspiratory effort, reflected by decreases in the pressure-time integral of the diaphragm and the inspiratory muscles. These were further reduced when FA was added. VA decreased the elastic work of breathing (Wel) whereas resistive work (Wres) tended to increase so that the fall in total work (W/tot) was less than expected. At each VA setting, the addition of FA significantly reduced Wres and, as a result, Wtot. These results demonstrate that PAV can improve breathing pattern while reducing inspiratory effort by specifically decreasing Wel and Wres, and that VA and FA should be used together to optimize reductions in Wtot and the efficacy of assistance provided.

A sequential study of experimental porcine paramyxovirus (LPMV) infection of pigs: immunostaining of cryostat sections and virus isolation

La Piedad Michoacan Paramyxovirus (LPMV) is a recently recognized paramyxovirus infecting pigs throughout Mexico. Disease syndromes observed in field cases associated with LPMV infection include neurologic, respiratory, and reproductive disorders. Clinical signs and the distribution of LPMV virus and antigen in tissue samples from pigs experimentally infected with LPMV by natural routes were studied. Severe neurologic disease and death occurred following experimental inoculation of 3- and 17-day-old pigs. All of the pigs inoculated at 3 days of age were either dead or moribund by 8 days after inoculation, whereas 30% of the pigs inoculated at 17 days of age were affected. Virus was consistently recovered from or demonstrated in tissues from the respiratory tract of both groups of pigs. LPMV and antigen were also demonstrated in central nervous system (CNS) tissues from these pigs; however, differences in virus distribution within the CNS were demonstrated in the 2 groups. In the pigs inoculated at 17 days of age, isolation of LPMV was restricted to the olfactory bulb and midbrain. In contrast, in the pigs inoculated at 3 days of age, isolation of LPMV was more widespread throughout the CNS tissue examined. Virus excretion studies indicated that nasal spread of LPMV was more important than fecal spread. Comparatively large quantities of infectious LPMV were consistently recovered from urine samples of experimentally infected pigs.

Childcare needs of female street vendors in Mexico City

This article reports on strategies developed by female street vendors (vendedoras ambulantes) in Mexico City to ensure the care of their young children in the absence of a specific and operational government policy to fulfil this need. The information concerning child care and health was gathered by a survey of 426 street traders selected by multi-stage random cluster sampling in four of the administrative districts (delegaciones politicas) of Mexico City during 1990. It was found that, as mothers of young children, street vendors most frequently looked after their children personally on the street or left them with other members of the family. Related factors were availability of alternative child care providers in the family, the age of the children and working conditions of the mother. Children who remained on the streets with their mothers suffered more frequently from gastro-intestinal diseases and accidents than the national average. The incidence of acute respiratory diseases, however, was similar in the cases of maternal care in the street and care by family members in another environment. Existing public health measures show a greater concern for the health of food consumers than that of workers in this area. Current public policy seeks to regulate street vending activities and to concentrate traders in ad hoc areas and facilities. Our research results document the need for actions that can contribute to an improvement in the care and health conditions of these young children.

High dose rate brachytherapy for the local control of endobronchial carcinoma following external irradiation

BACKGROUND

External irradiation is an established palliative treatment for patients with inoperable lung cancer. However, persistent or recurrent symptoms due to local disase are common following external irradiation. The impact of high dose rate (HDR) brachytherapy in the palliative management of patients with local sequelae of residual or recurrent endobronchial lung carcinoma following external irradiation was investigated.

METHODS

A prospective cohort of 29 patients (19 men, mean age 65 years) underwent HDR brachytherapy for inoperable lung cancer. All patients had completed external irradiation at least one month before entry into the study (mean (SD) dose 4400 (1481) cGy, completed 12.9 (21.3) months previously). Patients underwent outpatient bronchoscopic placement of 1-3 HDR brachytherapy catheters for delivery of 750-1000 cGy of intraluminal irradiation every two weeks on 1-3 occasions. Prospective evaluation before and four weeks after completion of HDR brachytherapy included assessment of indices of level of function, symptoms, extent of atelectasis (chest radiography), and bronchoscopic determination of degree of endobronchial obstruction.

RESULTS

One hundred and eighteen catheters were placed in 81 treatments. Eleven of the 26 patients who underwent repeat bronchoscopy showed a reduction in the degree of endobronchial obstruction; five of 18 patients had radiographic improvement in the extent of atelectasis. Positive response rates ranged from 25% for signs and symptoms related to pneumonitis to 69% for haemoptysis. Performance status improved in 24% of patients. Two patients died before completion of the study protocol. Short term complications included one episode of non-fatal, massive haemoptysis, five of minor haemoptysis, and one pneumothorax.

CONCLUSIONS

HDR brachytherapy may improve the degree of endobronchial obstruction, atelectasis, symptoms, and level of function with minimal short term complications in patients with recurrent or residual symptomatic disease following external irradiation.

Evaluation of diluents and media for enumerating Zygosaccharomyces rouxii in blueberry syrup

Combinations of diluents and enumeration media were evaluated for their efficacy in enumerating Zygosaccharomyces rouxii in blueberry syrup (aw 0.818, 0.870 and 0.921). Diluents consisted of deionized water containing 0.1% peptone, 20%, 30%, 40% or 50% glucose, 50% glucose plus 0.05% Tween 80, and 12%, 18%, 26% or 35% glycerol, all calculated on a w/w basis. Enumeration media were dichloran rose bengal chloramphenicol (DRBC) agar, tryptone glucose yeast extract (TGY) agar, dichloran 18% glycerol (DG18) agar, plate count agar containing 52% sucrose (PCA52S) and malt extract yeast extract 50% glucose (MY50G) agar. Two test strains of Z. rouxii grown in blueberry syrup for 7 or 14 days responded similarly to diluent/enumeration medium combinations. The use of 0.1% peptone diluent or DRBC agar in combination with other enumeration media or diluents was inferior for recovering Z. rouxii. As the aw of the blueberry syrup decreased, the sensitivity of Z. rouxii to diluent containing decreased concentrations of glucose increased. The use of glycerol as a solute in diluent did not result in a similar trend, indicating that the protective effect of glycerol against osmotic stress to Z. rouxii cells is greater than that of glucose at high aw and that cells adapted to low aw in blueberry syrup are more sensitive to high aw in diluents. The addition of 0.05% Tween 80 to 50% glucose diluent did not influence performance. Overall, diluents containing 50% glucose (aw 0.898), 18% glycerol (aw 0.956) or 26% glycerol (0.934), in combination with TGY agar (aw 0.982), resulted in the highest recovery of Z. rouxii from blueberry syrup at aw 0.818 to 0.921.

Influence of site of tracheal pressure measurement on in situ estimation of endotracheal tube resistance

In situ measurement of distal tracheal pressure (Ptr) via an intraluminal side-hole catheter (IC) has been used to determine endotracheal tube (Rett) and intrinsic patient (Rpt) resistances in intubated subjects. Because of differences in cross-sectional area between the endotracheal tube (ETT) and trachea, fluid dynamic principles predict that IC position should critically influence these results. Accordingly, the aim of this study was to determine the effect of IC position on Rett. Ptr was recorded in vitro through an IC from 2 cm inside, at the tip of, or 2 cm outside an ETT (7, 8, and 9 mm ID) situated within an artificial trachea (13, 18, and 22 mm ID). A reference value of Rett was also obtained. Results were unaffected by IC position during inspiration, overestimating Rett by 7.9 +/- 0.7% (SE). In contrast, during expiration, Rett fell as IC position changed from outside to inside the ETT and was underestimated by 41.3 +/- 3.6% with Ptr recorded inside the ETT. Varying ETT or tracheal size had little effect on the relative error in Rett. The IC itself did increase Rett due to a reduction in effective cross-sectional area, the change varying directly with IC size and inversely with ETT caliber. In vivo values in 11 intubated patients were comparable to in vitro results. In summary, IC position and size can have important consequences on in situ measurements of Ptr and should be considered when clinically monitoring Rett or Rpt.

Comparison of static and dynamic measurements of intrinsic PEEP in mechanically ventilated patients

Intrinsic positive end-expiratory pressure (PEEPi) is routinely determined under static conditions by occluding the airway at end-expiration (PEEPi,stat), the resulting plateau pressure representing the average PEEPi present within a nonhomogeneous lung. In contrast, PEEPi can also be evaluated dynamically (PEEPi,dyn) by recording the change in pressure required to initiate lung inflation. It has been suggested that PEEPi,dyn reflects the lowest regional PEEPi, and therefore underestimates PEEPi,stat in the presence of heterogenous mechanical properties. The purposes of this study were (1) to compare PEEPi obtained with these two methods in mechanically ventilated patients with significant airway obstruction (AWO) and those without (non-AWO), and (2) to relate any discrepancies observed with other indices of respiratory mechanics. PEEPi,stat, PEEPi,dyn, and respiratory mechanics were measured during controlled mechanical ventilation in 22 sedated, paralyzed patients. PEEPi,dyn was significantly less than PEEPi,stat in AWO, averaging 3.0 +/- 0.5 (SEM) and 9.3 +/- 1.1 (SEM) cm H2O, respectively (p < 0.0001). In contrast, these values were more comparable in non-AWO, averaging 4.6 +/- 0.8 and 5.4 +/- 1.0 cm H2O (p > 0.05). As a result, the ratio of PEEPi,dyn to PEEPi,stat amounted to 0.36 +/- 0.06 for AWO compared with 0.87 +/- 0.05 in non-AWO (p < 0.005). Maximal (Rmax) and minimal (Rmin) respiratory resistance were greater in AWO whereas respiratory compliance (Crs) was no different between groups. PEEPi,dyn/PEEPi,stat was inversely related to delta P, the pressure losses attributable to time constant inequalities and viscoelastic tissue properties (r = 0.64, p < 0.005). No correlation was found between this ratio and Rmax, Rmin, or Crs.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of static and dynamic measurements of intrinsic PEEP in anesthetized cats

Dynamic measurements of intrinsic positive end-expiratory pressure (PEEPi,dyn) considerably underestimate values obtained under static conditions (PEEPi,stat) in patients with severe airway obstruction. This may be related to regional differences in respiratory system mechanical properties and/or viscoelastic behavior. To evaluate this concept, PEEPi,stat and PEEPi,dyn were compared in six anesthetized paralyzed cats during dynamic hyperinflation produced by inverse ratio ventilation (IRV) and aerosolized methacholine (MCh). PEEPi,stat did not differ between IRV and MCh, averaging 2.70 +/- 0.33 (SE) and 2.70 +/- 0.25 cmH2O, respectively. PEEPi,dyn was significantly less with MCh (0.25 +/- 0.05 cmH2O) than IRV (2.05 +/- 0.28 cmH2O) (P < 0.0001), resulting in a lower PEEPi,dyn/PEEPi,stat ratio for MCh (0.10 +/- 0.02) than for IRV (0.76 +/- 0.03) (P < 0.0001). Compared with control values (33.5 +/- 3.7 cmH2O.l-1.s), maximum resistance (Rmax) was unchanged during IRV (29.1 +/- 2.1 cmH2O.l-1.s) but increased considerably with MCh (288.8 +/- 18.4 cmH2O.l-1.s) (P < 0.0001). Similar changes in minimum resistance (Rmin) and delta R (Rmax-Rmin) were noted. There was a strong inverse relationship between delta P, an index of time constant inequalities and viscoelastic pressure losses and PEEPi,dyn/PEEPi,stat ratio. No correlation was found between this ratio and Rmax, Rmin, delta R, or compliance. In conclusion, PEEPi,dyn considerably underestimates PEEPi,stat in acute nonhomogeneous airway obstruction with MCh in contrast to IRV, where the magnitude and distribution of mechanical properties remain unaltered. These findings support the concept that the difference between PEEPi,dyn and PEEPi,stat is related to regional time constant inequalities and/or increased viscoelastic pressure losses.