Effect of clarithromycin and omeprazole therapy on the diversity and stability of genotypes of Helicobacter pylori from duodenal ulcer patients

The genotypes of multiple isolates of Helicobacter pylori from 17 duodenal ulcer patients in the United Kingdom were compared to determine reasons for treatment failure. Isolates were from antrum and corpus biopsies taken before and after dual therapy with clarithromycin and omeprazole. All isolates were tested for antibiotic resistance and characterised by a novel scheme combining polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the ureA + ureB and 23S rRNA genes, vacA signal and midregion genotypes, and PCR detection of cagA. Combined genotypes of paired pre- and post-treatment isolates from 8 patients showed an infection with a single strain of H. pylori that had acquired resistance to clarithromycin. In 4 other patients, acquisition of clarithromycin resistance was associated with the presence of different strain types of H. pylori. The remaining 5 patients had clarithromycin-sensitive isolates. Overall, H. pylori from different patients had diverse genotypes, yet most (70%) were colonized by the same predominant and stable strain in both the antrum and corpus. There was no link between the emergence of in vitro clarithromycin resistance and a particular strain genotype for these UK isolates. It was concluded that colonization with a clarithromycin-resistant H. pylori was due to selection of a resistant strain or clonal variant within the infecting population. Present genomic markers had low predictive value for emergence of resistance.

Quality assurance by a commercial flow cytometry method of leucodepletion of whole blood donations: initial application of universal testing and proposals for a batch-release sampling plan

We have used the Becton-Dickinson LeucoCOUNT test to monitor residual leucocytes in whole blood by flow cytometry following leucodepletion filtration. This test was found to be quick, robust and reliable, and allowed measurement of residual leucocytes down to 2.25 x 104 leucocytes per unit, which was found to match approximately the limit of filter proficiency. The results of testing > 1000 units showed a lognormal distribution with means between log(10) 4.864 (0.73 x 105) and log(10) 5.016 (1.04 x 105) leucocytes per unit in the three different homogeneous groups of filtered units studied. The numbers of units with residual leucocytes exceeding the 5 x 106 upper threshold were 1/577, 2/457 and 0/87 in these groups. The filtration processes were validated according to the published BEST working party guidelines and were well within the 99% confidence and 95% tolerance target for the 5 x 106 upper threshold set for the UK. A sampling plan based on British Standard BS 6001 with elimination of outliers by the extreme studentized deviate (Grubbs' test) was evaluated on random samples from these groups and has been adopted locally as a prospective batch-release criterion for release of leucodepleted blood.

Oral staphylococcal mucositis: A new clinical entity in orofacial granulomatosis and Crohn's disease

OBJECTIVE

Orofacial granulomatosis and the oral manifestations of Crohn's disease comprise many clinical features, of which stomatitis is one. The purpose of this study was to establish a role for Staphylococcus aureus in mucositis affecting some patients with orofacial granulomatosis or oral Crohn's disease.

STUDY DESIGN

Four patients (2 with orofacial granulomatosis and 2 with oral Crohn's disease), from a total of 450 patients examined over 10 years, had stomatitis involving the entire oral mucosa, from which S aureus was cultured by the oral rinse technique. These patients were treated with flucloxacillin or erythromycin.

RESULTS

A heavy growth of S aureus was isolated from the mouth of each patient. All 4 patients responded to treatment with flucloxacillin or erythromycin.

CONCLUSIONS

S aureus is a potential cause of panstomatitis in patients with orofacial granulomatosis or Crohn's disease. This infection responds rapidly to antimicrobial treatment.

99Tcm-HMPAO leucocyte labelling in orofacial granulomatosis and gastrointestinal Crohn's disease in childhood and early adulthood

Orofacial granulomatosis is a granulomatous inflammatory disorder, affecting the soft tissues of the face and mouth. The predominant feature is disfiguring lip swelling. Patients with this condition may be exhibiting a Type IV hypersensitivity reaction to dietary or environmental allergens, or these may be the orofacial manifestations of underlying gastrointestinal Crohn's disease. The results of 99Tcm-HMPAO leucocyte labelling of the gastrointestinal tract in 14 patients with orofacial granulomatosis and 15 patients with known gastrointestinal Crohn's disease are presented, indicating that this is a useful and non-invasive screening test for the identification of gastrointestinal Crohn's disease in paediatric and young adult patients presenting with orofacial granulomatosis.

The bone marrow plasma cell labeling index by flow cytometry

The bone marrow plasma cell labeling index is the most important prognostic indicator for patients with multiple myeloma. Traditionally, this test has been performed as a two color immunofluorescent microscope technique which is time consuming and requires a degree of subjectivity in its interpretation. We have assessed various adaptations of this method to flow cytometry. A bromodeoxyuridine method has been compared with a propidium iodide DNA method to detect cells in S phase and CD38-FITC has been compared with CD38-FITC + CD138-FITC and CD38-biotin + streptavidin FITC to identify plasma cells. The mean channel fluorescent intensity of the plasma cell peaks for each of these markers was 12. 7, 17.4 and 35.3 respectively demonstrating the superiority of CD38-biotin + streptavidin FITC. Analysis after propidium iodide staining provided a good correlation with the slide technique (r = 0. 71; P < 0.0001) but the bromodeoxyuridine method did not correlate with the slide method (r = 0.09; P = NS). The labeling index values obtained from either of the flow methods were greater than the microscopic method. Thus a labeling index of >4% will replace the traditional >1% threshold for identifying patients with a significantly increased labeling index. The advantages of the new method are that it takes less time to perform, is more objective and provides additional data on ploidy and cell cycle status.

Long-term interferon-alpha 2A does not induce sustained hematologic remission in younger patients with essential thrombocythemia

The ability of Interferon alpha (alpha-IFN) to alter the natural history of essential thrombocythemia (ET) and induce sustained hematologic remission would provide further impetus to consider this agent in younger patients with this disease and may influence the decision to commence treatment in asymptomatic patients. This study has failed to demonstrate any sustained hematologic remissions after cessation of long-term (2 years) alpha-IFN administration in a group of 34 female patients with a median age of 41 years (range 14-68) who were considered at intermediate to high risk of thrombotic complications. In the twenty-one patients completing two years of therapy, 13 (62%) had complete hematological responses (CHR; platelet count <400 x 10(9)/L), 7 (33%) partial hematological responses (PHR; platelet count 400-600 x 10(9)/L) and no thrombotic or hemorrhagic complications occurred. In all patients who discontinued alpha-IFN at 2 years, platelet counts rose above the normal range within 1-4 months and the majority required reinstitution of some form of therapy. The inability of long-term alpha-IFN to induce sustained, unmaintained hematologic remission argues strongly against any significant effect on the neoplastic clone at the doses used in this study. This study does, however, confirm the efficacy of long-term alpha-IFN in younger female patients with ET, a group not previously well represented in clinical trials of the agent.

Factors affecting the outcome of allogeneic bone marrow transplantation for adult patients with refractory or relapsed acute leukaemia

We evaluated the outcome of allogeneic bone marrow transplantation (BMT) for advanced acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL) in 383 adult patients in nine Australian adult BMT centres between 1981 and 1997. The median overall survival for the group was 4.8 months, with an estimated 5-year survival of 18%. 28% of patients died of transplant-related toxicities within the first 100 d. Progressive disease was responsible for 48% of deaths. Multi-factor analysis demonstrated that AML (v ALL), disease status (second complete remission [CR2] v others), age (< 40 years) and duration of prior first complete remission (CR1) (> 6 months) were pre-transplant variables significantly associated with improved survival. Acute graft-versus-host disease (GVHD) of any grade reduced the rate of relapse in both AML and ALL, but only grades I-II were associated with improved survival. Both limited and extensive chronic GVHD were associated with increased survival. Only patients with AML in untreated first relapse or CR2, with a duration of CR1 > 6 months, or patients with T ALL, had a 5-year survival > 20%. Transplants for AML in induction failure or pre-B ALL in untreated first relapse or CR2 had an intermediate outcome, with 5-year survival of 10-20%. A 5-year survival of < 10% was observed for patients transplanted for ALL in induction failure or for pre-B ALL or AML in refractory first relapse or beyond CR2. These results suggest that for most adult patients with advanced acute leukaemia an allograft offers only a small chance of cure.

Spontaneous regression of an anaplastic large cell lymphoma in the oral cavity: first reported case and review of the literature

Lymphomas account for 2-5% of all oral malignancies and are the third most common in this site. This case report appears to be the first in the world literature describing spontaneous regression in the oral cavity of a subset of non-Hodgkins lymphomas known as Ki-1 anaplastic large cell lymphomas (ALCL). Ki-1 ALCL account for 2-7% of all non-Hodgkins lymphomas and the clinical presentation is variable; they may arise de novo or in the setting of a separate primary lymphoma and commonly present in the extra-nodal location. Disease severity is also variable with waxing and waning lesions at one extreme which may spontaneously regress to bone marrow involvement in around 12% of cases. This case is especially interesting since the patient is a farmer, given the recent evidence that there may be a link between non-Hodgkins lymphoma and this occupation.

Acute promyelocytic leukaemia complicating multiple myeloma: evidence of different cell lineages

The association of leukemia and multiple myeloma is well described usually as a complication of chemotherapy but also in the absence of chemotherapy or at diagnosis. Such leukemias are typically acute myeloid leukemia (AML), particularly myelomonocytic subtype, and cases of acute promyelocytic leuke (APL) are rarely reported. Controversy exists as to whether myeloma and AML originate from a single haematopoietic progenitor or arise from different cell lineages. We report a case of a 58 year old female who developed APL 10 months following diagnosis of nonsecretory light chain (kappa) myeloma which had been treated with local spinal irradiation and low dose oral melphalan and prednisone. Clonality had originally been demonstrated by light chain restriction (kappa) of her bone marrow plasma cells whilst immunoglobulin heavy chain and T cell receptor genes were germ line. At development of APL cytogenetics revealed t(15;17) and PML-RAR fusion gene was detected by RT-PCR. The patient was treated with all-trans retinoic acid (ATRA) and received 2 cycles of consolidation chemotherapy with Idarubicin. Following this therapy the t(15;17) and PML-RAR were both undetectable whilst the clonal population of kappa staining plasma cells persisted. This particular patient represents a rare case of APL complicating multiple myeloma with persistence of the myeloma clone but disappearance of PML-RAR alpha RNA following therapy. This case study appears to support the argument that the APL and myeloma originated from distinct cell lineages.

Analysis of the acute and chronic wound environments: the role of proteases and their inhibitors

To assess the differences in proteolytic activity of acute and chronic wound environments, wound fluids were collected from acute surgical wounds (22 samples) and chronic wounds (25 samples) of various etiologies, including mixed vessel disease ulcers, decubiti and diabetic foot ulcers. Matrix metalloproteinase (MMP) activity measured using the Azocoll assay was significantly elevated by 30 fold in chronic wounds (median 22.8 microg MMP Eq/ml) compared to acute wounds (median 0.76 microg MMP Eq/ml) (p < 0.001). The addition of the matrix metalloproteinase inhibitor Illomostat decreased the matrix metalloproteinase activity by approximately 90% in all samples, confirming that the majority of the activity measured was due to matrix metalloproteinases. Gelatin zymograms indicated predominantly elevated matrix metalloproteinase-9 with smaller elevations of matrix metalloproteinase-2. In addition tissue inhibitor of metalloproteinase-1 levels were analyzed in a small subset of acute and chronic wounds. When tissue inhibitor of metalloproteinase-1 levels were compared to protease levels there was an inverse correlation (p = 0.02, r = - 0.78). In vitro degradation of epidermal growth factor was measured by addition of 125I labelled epidermal growth factor to acute and chronic wound fluid samples. There was significantly higher degradation of epidermal growth factor in chronic wound fluid samples (mean 28.1%) compared to acute samples (mean 0.6%). This also correlated to the epidermal growth factor activity of these wound fluid samples (p < 0. 001, r = 0.64). Additionally, the levels of proteases were assayed in wound fluid collected from 15 venous leg ulcers during a nonhealing and healing phase using a unique model of chronic wound healing in humans. Patients with nonhealing venous leg ulcers were admitted to the hospital for bed rest and wound fluid samples were collected on admission (nonhealing phase) and after 2 weeks (healing phase) when the ulcers had begun to heal as evidenced by a reduction in size (median 12%). These data showed that the elevated levels of matrix metalloproteinase activity decreased significantly as healing occurs in chronic leg ulcers (p < 0.01). This parallels the processes observed in normally healing acute wounds. This data also supports the case for the addition of protease inhibitors in chronic wounds in conjunction with any treatments using growth factors.

Genomic organization and chromosomal localization of the human Coxsackievirus B-adenovirus receptor gene

Myocarditis and dilated cardiomyopathy (DCM) are common causes of morbidity and mortality in children. Many studies have implicated the enteroviruses and, particularly, the Coxsackievirus-B family as etiologic agents of the acquired forms of these diseases. However, we have shown the group-C adenoviruses to be as commonly detected as enteroviruses in the myocardium of children and adults with these diseases. It has remained something of a conundrum why two such divergent virus families cause these diseases. The recent description of the common human Coxsackievirus B-adenovirus receptor (CAR) offers at least a partial explanation. In order to characterize the CAR gene, we screened a bacterial artificial chromosomal (BAC) library (RPCI11) using a polymerase chain reaction (PCR) product derived from the 3' end of the CAR cDNA sequence. This identified 13 BACs that were further characterized by PCR amplification of seven contiguous regions of the entire cDNA sequence. Eleven of the BACs were determined to encode pseudogenes while the other two BACs (131J5 and 246M1) encoded the presumed functional gene. PCR amplification of a monochromosomal hybrid panel indicated the presence of pseudogenes on chromosomes 15, 18, and 21 while the functional gene is encoded on chromosome 21. Fluorescence in situ hybridization analysis indicated that the gene is located at 21q11.2. DNA sequencing of BACs 131J5 and 246M1 revealed the presence of seven exons. The DNA sequences have been determined for each exon-intron boundary, and putative promoter sequences and transcription initiation sites identified. No consensus polyadenylation signal was identified.

Comparison of icodextrin and glucose solutions for the daytime dwell in automated peritoneal dialysis

BACKGROUND

The sustained ultrafiltration achieved by icodextrin is more suited for the daytime dwell in automated peritoneal dialysis (APD) than glucose solutions.

METHODS

Seventeen patients receiving APD underwent assessment using three different solutions for the daytime dwell: 2.27% glucose, 3.86% glucose and 7.5% icodextrin. Patients were then observed on icodextrin for a 6 month period.

RESULTS

Daytime ultrafiltration was greater for 3.86% glucose (median 0.10, IQR 0.01 to 0.321) P<0.01 and icodextrin (median 0.26, IQR 0.14 to 0.361) P<0.001 than 2.27% glucose (median -0.19, IQR -0.54 to -0.081), with 3.86% glucose and icodextrin not being significantly different. Positive ultrafiltration occurred in 3/17 patients with 2.27% glucose, 13/17 patients with 3.86% glucose and 16/17 patients with icodextrin (chi2 P<0.0001). The difference in ultrafiltration of icodextrin and 3.86% glucose correlated with the 4 h dialysate/plasma creatinine ratio in a PET test (r = 0.51, P<0.05). Daytime Kt/V urea was greater for 3.86% glucose (median 0.27, IQR 0.20 to 0.48 per week, P<0.01) and icodextrin (median 0.31, IQR 0.27 to 0.49 per week, P<0.0001) than for 2.27% glucose (median 0.22, IQR 0.15 to 0.38 per week), with the difference between 3.86% glucose and icodextrin not reaching statistical significance (P = 0.06). Daytime creatinine clearance was greater for 3.86% glucose (median 10.2, IQR 6.9 to 13.61/week/1.73 m2, P<0.02) and icodextrin (median 12.1, IQR 9.3 to 15.71/week/1.73 m2, P<0.005) than for 2.27% glucose (median 8.8, IQR 4.9 to 11.91/week/1.73 m2). Daytime creatinine clearance was greater for icodextrin than for 3.86% glucose (P<0.005). The effects of icodextrin were sustained for the 6 month observation period.

CONCLUSIONS

Icodextrin produced enhanced ultrafiltration and clearances compared with 2.27% glucose, without the exposure of the peritoneum to hypertonic glucose solutions.

Syngeneic stem cell transplantation for HIV-related lymphoma

The treatment of human immunodeficiency virus (HIV)-related lymphoma is beset by a number of therapeutic limitations. High-dose chemotherapy followed by peripheral blood stem cell transplantation (PBSCT) for relapsed disease is one option, but may be compromised by unacceptable treatment-related morbidity and mortality. We describe an HIV-positive male with relapsed immunoblastic non-Hodgkin's lymphoma (NHL) who successfully received salvage chemotherapy followed by a syngeneic PBSCT from his HIV-negative (hepatitis C positive) brother. At 15 months post-transplant he remains in complete remission with low-level HIV viral load, an improved CD4 lymphocyte count and absent anti-hepatitis C antibodies. We believe selected patients with relapsed HIV-related NHL should be considered for high-dose therapy.

Prevalence of leg wound complications after coronary artery bypass grafting: determination of risk factors

BACKGROUND: The reported prevalence of leg wound complications after coronary artery bypass grafting is 2% to 24%. Decreased length of hospital stay for patients who have this surgical procedure poses new care requirements in both acute care and community settings. OBJECTIVE: To determine the prevalence of postoperative leg wound complications in patients undergoing coronary artery bypass grafting and the risk factors associated with these complications. METHOD: In this prospective, observational study, 547 consecutive patients who had coronary artery bypass grafting alone or in combination with other cardiac surgical procedures were examined for evidence of leg wound complications each day after surgery during hospitalization. After discharge, problems were detected by home care nurses. RESULTS: The prevalence of leg wound complications was 6.8%. Factors significant by multiple logistic regression included preoperative hospitalization, use of an Ace elastic bandage in the operating room, the length of time the leg incision remained open in the operating room, and administration of nicardipine intravenously in the intensive care unit. Odds ratios were calculated for each variable. Premorbid factors such as diabetes or peripheral vascular disease were not predictive of complications. On average, most problems occurred on postoperative day 10, when many patients were at home. CONCLUSIONS: The results highlight the need to detect complications early, in both the hospital and the community settings. The determination of factors related to poor outcomes may assist clinicians in improving healthcare delivery.

Prevalence of leg wound complications after coronary artery bypass grafting: determination of risk factors

BACKGROUND

The reported prevalence of leg wound complications after coronary artery bypass grafting is 2% to 24%. Decreased length of hospital stay for patients who have this surgical procedure poses new care requirements in both acute care and community settings.

OBJECTIVE

To determine the prevalence of postoperative leg wound complications in patients undergoing coronary artery bypass grafting and the risk factors associated with these complications.

METHOD

In this prospective, observational study, 547 consecutive patients who had coronary artery bypass grafting alone or in combination with other cardiac surgical procedures were examined for evidence of leg wound complications each day after surgery during hospitalization. After discharge, problems were detected by home care nurses.

RESULTS

The prevalence of leg wound complications was 6.8%. Factors significant by multiple logistic regression included preoperative hospitalization, use of an Ace elastic bandage in the operating room, the length of time the leg incision remained open in the operating room, and administration of nicardipine intravenously in the intensive care unit. Odds ratios were calculated for each variable. Premorbid factors such as diabetes or peripheral vascular disease were not predictive of complications. On average, most problems occurred on postoperative day 10, when many patients were at home.

CONCLUSIONS

The results highlight the need to detect complications early, in both the hospital and the community settings. The determination of factors related to poor outcomes may assist clinicians in improving healthcare delivery.

Hemodynamic consequences of high- and low-pressure capnoperitoneum during laparoscopic cholecystectomy

BACKGROUND

Peritoneal insufflation to 15 mmHg diminishes venous return and reduces cardiac output. Such changes may be dangerous in patients with a poor cardiac reserve. The aim of this study was to investigate the hemodynamic effects of high (15 mmHg) and low (7 mmHg) intraabdominal pressure during laparoscopic cholestectomy (LC) METHODS: Twenty patients were randomized to either high- or low-pressure capnoperitoneum. Anesthesia was standardized, and the end-tidal CO2 was maintained at 4.5 kPa. Arterial blood pressure was measured invasively. Heart rate, stroke volume, and cardiac output were measured by transesophageal doppler.

RESULTS

There were 10 patients in each group. In the high-pressure group, heart rate (HR) and mean arterial blood pressure (MABP) increased during insufflation. Stroke volume (SV) and cardiac output were depressed by a maximum of 26% and 28% (SV 0.1 > p > 0.05, cardiac output p > 0. 1). In the low-pressure group, insufflation produced a rise in MABP and a peak rise in both stroke volume and cardiac output of 10% and 28%, respectively (p < 0.05).

CONCLUSIONS

Low-pressure pneumoperitoneum is feasible for LC and minimizes the adverse hemodynamic effects of peritoneal insufflation.

Comparison of column ozone retrievals by use of an UV multifilter rotating shadow-band radiometer with those from Brewer and Dobson spectrophotometers

The U.S. Department of Agriculture UV-B Monitoring Program measures ultraviolet light at seven wavelengths from 300 to 368 nm with an ultraviolet multifilter rotating shadow-band radiometer (UV-MFRSR) at 25 sites across the United States, including Mauna Loa, Hawaii. Column ozone has been retrieved under all-sky conditions near Boulder, Colorado (40.177 degrees N, 105.276 degrees W), from global irradiances of the UV-MFRSR 332- and 305-nm channels (2 nm FWHM) using lookup tables generated from a multiple-scattering radiative transfer code suitable for solar zenith angles (SZA's) up to 90 degrees. The most significant sources of error for UV-MFRSR column ozone retrievals at SZA's less than 75 degrees are the spectral characterizations of the filters and the absolute calibration uncertainty, which together yield an estimated uncertainty in ozone retrievals of +/-4.0%. Using model sensitivity studies, we determined that the retrieved column ozone is relatively insensitive (<+/-2%) to typical variations in aerosol optical depth, cloud cover, surface pressure, stratospheric temperature, and surface albedo. For 5 months in 1996-1997 the mean ratio of column ozone retrieved by the UV-MFRSR divided by that retrieved by the collocated Brewer was 1.024 and for the UV-MFRSR divided by those from a nearby Dobson was 1.025. The accuracy of the retrieval becomes unreliable at large SZA's of more than 75 degrees as the detection limit of the 305-nm channel is reached and because of overall angular response errors. The UV-MFRSR advantages of relatively low cost, unattended operation, automated calibration stability checks using Langley plots, and minimal maintenance make it a unique instrument for column ozone measurement.

Brain tissue oxygenation during hemorrhagic shock, resuscitation, and alterations in ventilation

OBJECTIVES

Recently developed polarographic microelectrodes permit continuous, reliable monitoring of oxygen tension in brain tissue (PbrO2). The aim of this study was to investigate the feasibility and utility of directly monitoring PbrO2 in cerebral tissue during changes in oxygenation or ventilation and during hemorrhagic shock and resuscitation. We also sought to develop a model in which treatment protocols could be evaluated using PbrO2 as an end point.

METHODS

Licox Clark-type polarographic probes were inserted in the brain tissue of 16 swine to monitor PbrO2. In eight swine, changes in PbrO2 were observed over a range of fractional concentrations of inspired O2 (FiO2) as well as during periods of hyperventilation and hypoventilation. In eight other swine, PbrO2 was monitored during a graded hemorrhage of up to 70% estimated blood volume and during the resuscitation period.

RESULTS

When FiO2 was elevated to 100%, PbrO2 increased from a baseline of 15+/-2 mm Hg to 36+/-11 mm Hg. Hyperventilation while breathing 100% oxygen resulted in a 40% decrease in PbrO2 (p < 0.05), whereas hypoventilation increased PbrO2 to 88 mm Hg (p < 0.01). A graded hemorrhage to 50% estimated blood volume significantly reduced PbrO2, mean arterial pressure, and intracranial pressure (p < 0.01). Continued hemorrhage to 70% estimated blood volume resulted in a PbrO2 of 2.9+/-1.5 mm Hg. After resuscitation, PbrO2 was significantly elevated, reaching 65+/-13 mm Hg (p < 0.01), whereas mean arterial pressure and cerebral perfusion pressure simply returned to baseline.

CONCLUSION

Directly measured PbrO2 was highly responsive to changes in FiO2, ventilatory rate, and blood volume in this experimental model. In particular, hypoventilation significantly increased PbrO2, whereas hyperventilation had the opposite effect. The postresuscitation increase in PbrO2 may reflect changes in both O2 delivery and O2 metabolism. These experiments set the stage for future investigations of a variety of resuscitation protocols in both normal and injured brain.

Inhibition of delayed rectifier K+ channels by dexfenfluramine (Redux)

In light of recent reports linking K+ channel modulation with food intake and macronutrient preference, we investigated the effect of anorectic agent dexfenfluramine (d-FF), a 5-HT reuptake inhibitor and releasing agent, on the delayed rectifier K+ (DRK) channels in rat lingual taste cells using the patch-clamp technique in whole-cell configuration. In a concentration-dependent manner, d-FF caused a reduction of the DRK currents in taste cells with an IC50 of 30.5 microM. Other anorectics that promote 5-HT activity such as fenfluramine, sibutramine and m-chlorophenylpiperazine (a specific 5-HT2C receptor agonist) produced inhibition of DRK currents of a similar pattern with a respective IC50 of 69.0, 8.6 and 95.4 microM. The actions of all compounds had rapid onset and were readily reversible. The inhibitory effects were not secondary to their stimulation of 5-HT, because direct application of 5-HT up to 1 mM did not alter DRK current. In addition, d-FF-induced current reduction was not prevented by either the 5-HT synthesis inhibitor p-chlorophenylalanine or 5-HT receptor antagonist metergoline. d-FF was also tested in cardiac ventricular myocytes that are reportedly abundant in DRK channels and was found to depress the DRK currents concentration-dependently with an IC50 of 250.9 microM. These results indicate an important pharmacological role for d-FF as an inhibitor of the DRK channels. The common inhibitory effect on DRK channels in oral taste cells and cardiac cells by this class of compounds might contribute to the anorectic and some of the detrimental cardiovascular effect associated with long-term exposure.

B-cell chronic lymphocytic leukaemia with CD8 expression: report of 10 cases and immunochemical analysis of the CD8 antigen

We report 10 cases of B-cell chronic lymphocytic leukaemia (B-CLL) with expression of the T-cell antigen CD8. The majority of patients had typical B-cell CLL with stable and non-progressive stage A(O) disease except for more common expression of lambda light chain and CD25. Two patients had progressive disease and required therapy, one with atypical morphological and phenotypic features. The incidence of CD8 expression was approximately 0.5% of B-CLL patients from our institutions. Immunoprecipitation of the CD8 antigen from four of these B-CLLs showed identity to the CD8 antigen expressed on T cells with precipitation of CD8alpha bands of molecular weight approximately 34 kD. In view of the known intracellular signalling mechanism of CD8 using the tyrosine kinase p56-lck, we studied p56-lck expression by Western blot and found lack of consistent expression of the CD8 surface antigen, with most lacking p56-lck. Our report indicates that CD8 expression in B-CLL is probably underrecognized but is not a marker of disease progression. The CD8 on the B-CLL surface is immunochemically identical to the antigen on T cells, but is not accompanied by its usual signalling mechanism of p56-lck tyrosine kinase and therefore is unlikely to be a functionally active receptor.

The expression of T cell related costimulatory molecules in multiple myeloma

Presentation of tumour antigen by malignant cells not expressing costimulatory molecules is considered to be a major cause of the failure of the host's immune response against tumours. This study has determined the expression of the B7 family of costimulatory molecules on malignant plasma cells and the expression of the counter receptor molecules, CD28 and CD152 (CTLA-4), on T cells of patients with multiple myeloma. CD28 expression was present on most CD4 cells but was lower on CD8 cells especially from those patients who also showed evidence of expanded T cell clones (median 40%. z=2.4; p<0.02). CD152 expression was increased in 50% (9/18) of patients with myeloma. CD80 (B7-1) expression was present on the plasma cells of only 1 of 27 samples but CD86 (B7-2) expression within the normal range was present on the plasma cells of 14 of 27 samples. Primitive plasma cells (CD38++ CD45++) had a higher expression of CD86 (median 78%) than mature plasma cells (CD38++ CD45-) (median 19%, z=3.7; p<0.01). Thus patients with expanded T cell clones have a downregulated T cell CD28 expression and lack B7-1 expression on their malignant plasma cells. These results are consistent with the concept that engagement of the T cell receptor by tumour antigen on B7-1 deficient malignant plasma cells would result in T cell anergy rather than productive immunity.