Evidence that Spt10 and Spt21 of Saccharomyces cerevisiae play distinct roles in vivo and functionally interact with MCB-binding factor, SCB-binding factor and Snf1

Mutations in SPT10 and SPT21 of Saccharomyces cerevisiae have been previously shown to cause two prominent mutant phenotypes: (1) defects in transcription of particular histone genes and (2) suppression of Ty and delta-insertion mutations (Spt(-) phenotype). The requirement for Spt10 and Spt21 for transcription of particular histone genes suggested that they may interact with two factors previously shown to be present at histone loci, SBF (Swi4 and Swi6) and MBF (Mbp1 and Swi6). Therefore, we have studied swi4Delta, mbp1Delta, and swi6Delta mutants with respect to histone gene transcription and for interactions with spt10Delta and spt21Delta. Our results suggest that MBF and SBF play only modest roles in activation of histone gene transcription. In addition, we were surprised to find that swi4Delta, mbp1Delta, and swi6Delta mutations suppress the spt21Delta Spt(-) phenotype, but not the spt21Delta defect in histone gene transcription. In contrast, both swi4Delta and mbp1Delta cause lethality when combined with spt10Delta. To learn more about mutations that can suppress the spt21Delta Spt(-) phenotype, we performed a genetic screen and identified spt21Delta suppressors in seven additional genes. Three of these spt21Delta suppressors also cause lethality when combined with spt10Delta. Analysis of one spt21Delta suppressor, reg1, led to the finding that hyperactivation of Snf1 kinase, as caused by reg1Delta, suppresses the Spt(-) phenotype of spt21Delta. Taken together, these genetic interactions suggest distinct roles for Spt21 and Spt10 in vivo that are sensitive to multiple perturbations in transcription networks.

Capecitabine and vinorelbine in elderly patients (≥65 years) with metastatic breast cancer: a phase I trial (SAKK 25/99)

BACKGROUND

Few chemotherapy regimens are suitable for the treatment of elderly patients with advanced breast cancer. With the aim of finding a regimen with a low burden of subjective non-overlapping toxic effects, vinorelbine and capecitabine were chosen to be investigated in a phase I dose-finding study.

PATIENTS AND METHODS

Thirty-six patients with advanced breast cancer were stratified for the presence of bone and non-bone involvement and treated at four dose levels from capecitabine 800 mg/m2 orally days 1-14 and vinorelbine 20 mg/m2 intravenously days 1 and 8, to capecitabine 1250 mg/m2 orally days 1-14 and vinorelbine 25 mg/m2 intravenously days 1 and 8, for a maximum of six cycles. None of the patients had received prior chemotherapy for metastatic/advanced disease. Fifty-three per cent of patients with bone metastases and 67% of patients without bone metastases had visceral disease. The median age was 70 years for the 15 with bone involvement patients and 73 years for the 21 without bone involvement patients.

RESULTS

Twenty-eight patients were fully evaluable for hematological dose-limiting toxicity (DLT), and all patients for other DLTs and for antitumor activity. One DLT with grade 3 venous thrombosis at dose level 2 and two dose-limiting neutropenia events at level 3 occurred in patients without bone involvement. Two dose-limiting neutropenia events were observed at dose level 2 for patients with bone involvement. Thus, the recommended dose was defined at level 1 (capecitabine 1000 mg/m2 days 1-14 and vinorelbine 20 mg/m2 days 1 and 8) for patients with bone involvement. For patients without bone involvement, the recommended dose was at level 2 (capecitabine 1250 mg/m2 days 1-14 and vinorelbine 20 mg/m2 days 1 and 8). For patients without bone involvement the overall response rate was 48% and the time to progression (TTP) was 4.5 months [95% confidence interval (CI) 3.3-6.9]. For patients with bone involvement the overall response rate was 53% and TTP was 5.3 months (95% CI 2.7-7.8).

CONCLUSIONS

This regimen of capecitabine and vinorelbine is well tolerated and effective in elderly patients with metastatic breast cancer. Toxicity was mainly hematological and was observed at a lower dose in patients with bone involvement. A phase II study with the two different dose levels for elderly patients with and without bone involvement is currently being conducted.

Topical estrogen protects against SIV vaginal transmission without evidence of systemic effect

BACKGROUND

Accumulating data suggest that the state of the vaginal epithelium affects a woman's risk of HIV vaginal transmission and several human and non-human primate studies have shown that the rate of HIV or SIV vaginal transmission is decreased when estrogen is dominant. Systemic estrogen can protect against SIV vaginal transmission.

OBJECTIVE

To determine the safety and efficacy of topical estrogen in preventing SIV vaginal transmission.

DESIGN

The non-human primate model of HIV vaginal transmission was used to assess vaginal estriol cream in ovariectomized macaques.

METHODS

Twelve macaques were treated intravaginally with estriol and eight with placebo cream twice a week. The vaginal and systemic effects of estriol were determined by colposcopy and serum luteinizing hormone, levels of which would decline in the presence of systemic estrogen. After 5 weeks of therapy, the animals were challenged vaginally with pathogenic SIVmac251.

RESULTS

Vaginal estriol resulted in minimal serum estriol levels and had no effect on serum luteinizing hormone levels. Vaginal epithelia cornified and thickened significantly in response to estriol therapy. One of the estriol-treated animals became infected after this single challenge, while six of the control animals became infected (P = 0.0044).

CONCLUSIONS

These data demonstrate that topical vaginal estriol can strongly protect against SIV vaginal transmission, while having no detectable systemic effect. These results support the study of topical vaginal estriol in preventing HIV vaginal transmission in at-risk women.

Control of the temporal fidelity of synaptic transmission by a presynaptic high voltage-activated transient K+ current

The type of K(+) channels controlling the waveform of the presynaptic spike and synaptic transmission were examined in the lamprey spinal cord. Reticulospinal neuron somata displayed a transient K(+) current with a high voltage-activation and inactivation. This current was selectively blocked by catechol at 100 microM. Reticulospinal axons also displayed a high voltage-activated fast K(+) current sensitive to catechol. The function of this presynaptic high voltage-activated fast K(+) current in controlling synaptic transmission was investigated by using paired intracellular recordings from reticulospinal axons and their targets. Blockade of this current by catechol (100 microM) prolonged the presynaptic spike elicited by a single stimulus leading to a potentiation of the postsynaptic EPSP. Calcium imaging of reticulospinal axons showed an increase in presynaptic calcium transients after blockade of the presynaptic K(+) current by catechol. During high frequency firing, catechol revealed an activity-dependent decrease in the spike duration, which resulted in a depression of synaptic transmission. These results suggest that the presynaptic high voltage-activated transient K(+) current acts to optimize the temporal fidelity of synaptic transmission by minimizing activity-dependent changes in the presynaptic spike waveform and calcium dynamics.

Spt10-dependent transcriptional activation in Saccharomyces cerevisiae requires both the Spt10 acetyltransferase domain and Spt21

Histone levels are a key factor in several nuclear processes, including transcription and chromosome segregation. Previous studies have demonstrated that Spt10 and Spt21 are required for the normal transcription of a subset of the histone genes in Saccharomyces cerevisiae, and sequence analysis has suggested that Spt10 is an acetyltransferase. We have now characterized several aspects of transcriptional activation of histone genes by Spt10 in vivo. Our results show that activation by Spt10 is dependent on its acetyltransferase domain. At HTA2-HTB2, the histone locus whose transcription is most strongly dependent on Spt10, Spt10 is physically recruited to the promoter in an Spt21-dependent and a cell cycle-dependent manner. Furthermore, Spt10 and Spt21 directly interact. These results, taken together with the identification of spt10 mutations that suppress an spt21Delta mutation, suggest a model for transcriptional activation by Spt10 and Spt21.

Glufosfamide administered using a 1-hour infusion given as first-line treatment for advanced pancreatic cancer. A phase II trial of the EORTC-new drug development group

The activity of glufosfamide (beta-D-glucopyranosyl-N,N'-di-(2-chloroethyl)-phosphoric acid diamide) against pancreatic cancer was investigated in a multicentre, phase II clinical study. Chemotherapy-nai;ve patients with advanced or metastatic disease were treated with glufosfamide (5 g/m(2)) using a 1-h intravenous (i.v.) infusion every 3 weeks. Patients were randomised between active-hydration and normal fluids to evaluate the nephroprotective effect of forced diuresis. Patients experiencing >0.4 mg/dl (>35 micromol/l) increase in serum creatinine compared with their baseline value were taken off treatment for safety reasons. The evaluation of response was according to the Response evaluation criteria in solid tumours (RECIST). Blood sampling was performed for pharmacokinetic analyses. 35 patients from 13 institutions were registered over a 13-month period. A total of 114 treatment cycles (median 3, range 1-8) were administered to 34 patients; 18 patients were allocated to the hydration arm. Overall haematological toxicity was mild. Metabolic acidosis occurred in 2 patients treated in the active-hydration arm, grade 3 hypokalaemia was recorded in 5 patients and grade 3 hypophosphataemia in 4 patients. One patient had a grade 4 increase in serum creatinine level, concomitantly to disease progression. Active-hydration did not show a nephroprotective effect and the plasma pharmacokinetics (Pk) of glufosfamide was not significantly influenced by hydration. Two confirmed partial remissions (PR) were reported (response rate 5.9%, 95% Confidence Interval (CI) 0.7-19.7%) and 11 cases obtained disease stabilisation (32.4%). An extra mural review panel confirmed all of the responses. Median overall survival was 5.3 months (95% CI 3.9-7.1) and time to progression (TTP) was 1.4 months (95% CI 1.3-2.7). In conclusion, glufosfamide administered using a 1-h infusion every 3 weeks has a modest activity in advanced pancreatic adenocarcinoma. Haematological toxicity is particularly mild, but regular monitoring of renal function is recommended.

Bone marrow-derived stem cells initiate pancreatic regeneration

We show that transplantation of adult bone marrow-derived cells expressing c-kit reduces hyperglycemia in mice with streptozotocin-induced pancreatic damage. Although quantitative analysis of the pancreas revealed a low frequency of donor insulin-positive cells, these cells were not present at the onset of blood glucose reduction. Instead, the majority of transplanted cells were localized to ductal and islet structures, and their presence was accompanied by a proliferation of recipient pancreatic cells that resulted in insulin production. The capacity of transplanted bone marrow-derived stem cells to initiate endogenous pancreatic tissue regeneration represents a previously unrecognized means by which these cells can contribute to the restoration of organ function.

Bone marrow-derived stem cells initiate pancreatic regeneration

We show that transplantation of adult bone marrow-derived cells expressing c-kit reduces hyperglycemia in mice with streptozotocin-induced pancreatic damage. Although quantitative analysis of the pancreas revealed a low frequency of donor insulin-positive cells, these cells were not present at the onset of blood glucose reduction. Instead, the majority of transplanted cells were localized to ductal and islet structures, and their presence was accompanied by a proliferation of recipient pancreatic cells that resulted in insulin production. The capacity of transplanted bone marrow-derived stem cells to initiate endogenous pancreatic tissue regeneration represents a previously unrecognized means by which these cells can contribute to the restoration of organ function.

Acetoacetate increases expression of intercellular adhesion molecule-1 (ICAM-1) in human brain microvascular endothelial cells

It has been hypothesized that ketone bodies cause activation of brain endothelial cells and that this is a factor in the intracerebral crises of diabetic ketoacidosis (DKA). In this study we used cultured human brain microvascular endothelial cells (HBMEC) to investigate the effect of beta hydroxybutyrate (BOHB) and acetoacetate (AcAc) on the expression of the adhesion molecule, intercellular adhesion molecule-1 (ICAM-1). Increasing concentrations of AcAc, but not BOHB, caused a significant upregulation of ICAM-1 in comparison to unstimulated cells. Glucose concentrations of 10 and 30 mM, but not 50 mM, also resulted in increased expression of ICAM-1. These results support the hypothesis that activation of HBMEC is involved in the acute complications of DKA, and that ketone bodies and hyperglycemia are factors in the perturbed membrane function.

Phase I and pharmacokinetic studies of PNU-159548, a novel alkycycline, administered intravenously to patients with advanced solid tumours

PNU-159548 (4-demethoxy-3'-deamino-3'-aziridinyl-4'-methylsulphonyl-daunorubicin) is the lead compound of a novel class of cytotoxic agents (alkycyclines) with a unique mechanism of action combining DNA intercalation with alkylation of guanines in the DNA major groove. The objectives of two phase I studies were to assess the dose-limiting toxicities (DLTs), to determine the maximum tolerated dose (MTD) and to study the pharmacokinetics (PKs) of PNU-159548 and its active metabolite PNU-169884 when administered intravenously (i.v.) over 10 or 60 min to patients with advanced solid tumours. Patients were treated with escalating doses of PNU-159548, courses repeated every 21 days at doses ranging from 1.0 to 16 mg/m(2). For pharmacokinetic analysis, plasma sampling was performed during the first course and assayed using a validated high-performance liquid chromatographic assay with mass spectrometric detection. 69 patients received a total of 161 courses. The MTD was reached at 14 and 16 mg/m(2) in heavily (HP) and minimally pretreated/non-pretreated (MP) patients, respectively, with thrombocytopenia as the DLT. A hypersensitivity reaction was observed in 8 patients across all dose levels, characterised by fever with chills, erythema, facial oedema and dyspnoea. The PKs of PNU-159548 and PNU-169884 were linear over the dose range studied. A significant correlation was observed between the percentage decrease in platelet count and the AUC of PNU-159548. In these studies, the DLT of PNU-159548 was thrombocytopenia. The recommended dose for phase II studies of PNU-159548 is 12 and 14 mg/m(2) administered i.v. over 10 min, once every 21 days, in HP and MP patients, respectively.

Haptenation of sulfonamide reactive metabolites to cellular proteins

Adverse drug reactions are a major problem complicating medical therapy. The pathogenesis of many severe adverse drug reactions, notably hypersensitivity reactions, is poorly understood. The sulfonamides are associated with severe hypersensitivity reactions. The initial pathogenesis seems to be caused by bioactivation of the parent drug to a reactive intermediate and subsequent propagation by the immune system. The determinants of the immune response are not known. We explored the formation of sulfonamide haptens in Molt-3 and HEPA 1C1C7 cells after incubation with sulfamethoxazole (SMX), the hydroxylamine of sulfamethoxazole (SMX-HA), or the nitroso of sulfamethoxazole (SMX-NO). Haptenation was demonstrated with SMX-HA and SMX-NO but not SMX; this occurred at concentrations below that associated with toxicity (significant haptenation was seen at 25 to 50 microM). Thus, haptenation occurred presumably onto viable cells. Haptenation occurred rapidly; haptenation of cell surface proteins was demonstrated within 5 min. This did not occur indiscriminately; confocal microscopy demonstrated haptenation onto specific sites on the cell membrane. We found that haptenation was significantly inhibited by thiols and other antioxidants (p < 0.05). Sulfonamide-specific haptens were rapidly internalized by what seemed to be a caveolae-dependent process. It seems that sulfonamide reactive metabolites haptenated specific cell surface proteins that are rapidly internalized. Understanding the specific protein target(s) for haptenation and how these haptens are processed will be important in understanding the immune mediation of sulfonamide hypersensitivity adverse drug reactions.

Prospective two year follow up study comparing novel and conventional imaging procedures in patients with arthritic finger joints

OBJECTIVE

To carry out a prospective two year follow up study comparing conventional radiography, three-phase bone scintigraphy, ultrasonography (US), and three dimensional (3D) magnetic resonance imaging (MRI) with precontrast and dynamic postcontrast examination in detecting early arthritis. The aim of the follow up study was to monitor the course of erosions during treatment with disease modifying antirheumatic drugs by different modalities and to determine whether the radiographically occult changes like erosive bone lesions of the finger joints detected by MRI and US in the initial study would show up on conventional radiographs two years later. Additionally, to study the course of soft tissue lesions depicted in the initial study in comparison with the clinical findings.

METHODS

The metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints (14 joints) of the clinically more severely affected hand (soft tissue swelling and joint tenderness) as determined in the initial study of 49 patients with various forms of arthritis were examined twice. The patients had initially been divided into two groups. The follow up group I included 28 subjects (392 joints) without radiographic signs of destructive arthritis (Larsen grades 0-1) of the investigated hand and wrist, and group II (control group) included 21 patients (294 joints) with radiographs showing erosions (Larsen grade 2) of the investigated hand or wrist, or both, at the initial examination.

RESULTS

(1) Radiography at the two year follow up detected only two erosions (two patients) in group I and 10 (nine patients) additional erosions in group II. Initial MRI had already detected both erosions in group I and seven (seven patients) of the 10 erosions in group II. Initial US had depicted one erosion in group I and four of the 10 erosions in group II. (2) In contrast with conventional radiography, 3D MRI and US demonstrated an increase in erosions in comparison with the initial investigation. (3) The abnormal findings detected by scintigraphy were decreased at the two year follow up. (4) Both groups showed a marked clinical improvement of synovitis and tenosynovitis, as also shown by MRI and US. (5) There was a striking discrepancy between the decrease in the soft tissue lesions as demonstrated by clinical findings, MRI, and US, and the significant increase in erosive bone lesions, which were primarily evident at MRI and US.

CONCLUSIONS

Despite clinical improvement and a regression of inflammatory soft tissue lesions, erosive bone lesions were increased at the two year follow up, which were more pronounced with 3D MRI and less pronounced with US. The results of our study suggest that owing to the inadequate depiction of erosions and soft tissue lesions, conventional radiography alone has limitations in the intermediate term follow up of treatment. US has a high sensitivity for depicting inflammatory soft tissue lesions, but dynamic 3D MRI is more sensitive in differentiating minute erosions.

Infection control in the intensive care unit. The role of the ventilator circuit

Patients are more likely to develop VAP from secretions aspirated past the cuff of the endotracheal tube than by what is breathed through the endotracheal tube. It may be more accurate to use the term "airway-associated pneumonia" rather than "ventilator-associated pneumonia" Several studies have now reported no change in VAP rates when circuits are only changed on an at-needed basis. There is also accumulating evidence that passive humidifiers and closed suction catheters do not need to be changed on a daily basis.

Noninvasive pressure support ventilation

In appropriately selected patients, NPPV decreases intubation rate, improves survival, and is cost-effective. Pressure support ventilation is commonly used successfully for NPPV. An issue with the use of pressure support is the ability of the ventilator to detect the end of inhalation in the presence of leaks or in patients with severe airflow obstruction. A concern with portable pressure ventilators is the potential for rebreathing of carbon dioxide. Despite these issues, pressure support ventilation has been used successfully for noninvasive ventilation in thousands of patients with acute respiratory failure.

Aerosol delivery during mechanical ventilation

Aerosols can be delivered during mechanical ventilation using either a nebulizer or MDI. The MDI is the most efficient method of aerosol delivery, whereas the greatest absolute amount of drug delivery is with the nebulizer.

Analysis of mitochondrial antigens reveals inner membrane succinate dehydrogenase flavoprotein subunit as autoantigen to antibodies in anti-M7 sera

The role of mitochondrial proteins as antigens to antibodies of anti-M7 sera was analysed by flavin fluorescence, one- and two-dimensional Western blots and blue native gel electrophoresis. Flavin fluorescence of succinate dehydrogenase (SucDH, complex II of the respiratory chain) of rat liver inner mitochondrial membranes correlated with the immunoreactivity of a representative anti-M7 myocarditis serum. Antigens of isolated bovine heart mitochondria reacting with antibodies of myocarditis serum on two-dimensional Western blots were identified by MALDI-TOF and NanoESI mass spectrometry as myosin heavy chain beta and as dihydrolipoamide dehydrogenase of the mitochondrial 2-oxoacid dehydrogenase complexes. The SucDH-flavoprotein was not resolved as a discrete protein spot on two-dimensional polyacrylamide gels. However, separation of the rat liver inner mitochondrial membrane complexes by blue native gel electrophoresis followed by Western blotting, and Western blots of purified Escherichia coli SucDH complex revealed that anti-M7 sera contained antibodies directed against the SucDH-flavoprotein subunit.

Marrow stromal cells form guiding strands in the injured spinal cord and promote recovery

Marrow stromal cells (MSC) can be expanded rapidly in vitro and differentiated into multiple mesodermal cell types. In addition, differentiation into neuron-like cells expressing markers typical for mature neurons has been reported. To analyze whether such cells, exposed to differentiation media, could develop electrophysiological properties characteristic of neurons, we performed whole-cell recordings. Neuron-like MSC, however, lacked voltage-gated ion channels necessary for generation of action potentials. We then delivered MSC into the injured spinal cord to study the fate of transplanted MSC and possible effects on functional outcome in animals rendered paraplegic. MSC given 1 week after injury led to significantly larger numbers of surviving cells than immediate treatment and significant improvements of gait. Histology 5 weeks after spinal cord injury revealed that MSC were tightly associated with longitudinally arranged immature astrocytes and formed bundles bridging the epicenter of the injury. Robust bundles of neurofilament-positive fibers and some 5-hydroxytryptamine-positive fibers were found mainly at the interface between graft and scar tissue. MSC constitute an easily accessible, easily expandable source of cells that may prove useful in the establishment of spinal cord repair protocols.

High-frequency ventilation design and equipment issues

Various technical approaches to high-frequency ventilation are available. Of these, HFOV is used most commonly. As high-frequency ventilation becomes increasingly used in the care of adult patients, the technical issues related to this therapy will become increasingly important.

Ventilator modes used in weaning

Weaning techniques include spontaneous breathing trials (SBTs), pressure-support ventilation (PSV), and synchronized intermittent mandatory ventilation (SIMV). SBTs can be conducted using one of several approaches, including T-piece breathing, low-level continuous positive airway pressure, low-level PSV, or setting the ventilator to flow-triggering with no pressure applied to the airway. The SBT can be used as a method to identify extubation readiness or as a weaning technique in which the duration of the trial is gradually increased over time. With pressure-support weaning, the level of pressure support is gradually reduced over time. With weaning using SIMV, the mandatory rate setting on the ventilator is gradually reduced. Randomized controlled trials have reported the poorest weaning outcomes using SIMV. Although new ventilator modes have been introduced to facilitate weaning, to date there is no evidence to support the use of these modes. Noninvasive positive-pressure ventilation also has been reported to facilitate weaning, but the ability to generalize these findings remains to be determined.

CD40/154 blockade and rejection of islet allografts in the streptozotocin and autoimmune diabetic rat

Islet transplantation in children with autoimmune diabetes will require immunosuppression that has minimal toxicity and side-effects, and overcomes the barrier of autoimmunity. Since antibodies directed against the CD40/154 co-stimulatory pathway may meet these criteria, we have tested the ability of hamster antirat CD154 (AH.F5, Biogen) to prevent rejection of renal subcapsular islet allografts in streptozotocin (STZ) or autoimmune (AUTO) diabetic diabetes-resistant biobreeding (DRBB) rats. STZ diabetic rats that received anti-CD154 at 15 mg/kg per dose but not 10 mg/kg per dose did not have evidence of rejection until about 80-120 d post-transplantation, by which time antibody concentrations had returned to undetectable levels. Rats retreated with anti-CD154 before recurrence of diabetes had a prolonged period of disease-free survival. Most of these rats had recurrence following a spleen cell challenge. In contrast, AUTO diabetic DRBB rats treated with anti-CD154 had recurrence of diabetes between 7 and 12 d following transplantation of the Dark Agouti (DA) islets. In a separate set, AUTO diabetic rats that received a simultaneous islet isograft, islet allograft and thyroid allograft had focal accumulation of lymphocytes at the periphery of the isograft, while the islet and thyroid allografts had diffuse infiltration with lymphocytes and destruction of tissue with no residual staining for glucagon. Therefore, autoimmunity adds an additional barrier to islet allotransplantation that is not overcome with CD40/154 blockade in an animal model that closely parallels autoimmune diabetes in humans. The results indicate the importance of testing regimen of islet transplantation in animal models of autoimmune diabetes.