Association of gastroduodenal disease phenotype with ABO blood group and Helicobacter pylori virulence-specific serotypes

AIMS

To investigate the prevalence of Helicobacter pylori infection in Lebanon and the association between virulence factors (cytotoxin-associated gene A and vacuolating cytotoxin gene A), ABO blood groups, and disease phenotype.

METHODS

One hundred and thirty symptomatic patients with H. pylori-associated endoscopic findings and 104 healthy male donors (age range 18-55) were evaluated. Both, patients and donors underwent ABO blood typing and Western blot for cytotoxin-associated gene A and vacuolating cytotoxin gene A.

RESULTS

The prevalence of H. pylori infection in healthy donors is 68.3%. Type I (cytotoxin-associated gene A- and vacuolating cytotoxin gene A-positive) was the predominant phenotype in all groups, though significantly less common in the asymptomatic population (46.5%) than in patients with benign disease (71.4%, p<0.01) or malignancy (71.6%, p<0.05). Type II (cytotoxin-associated gene A- and vacuolating cytotoxin gene A-negative) and vacuolating cytotoxin gene A-only strains were more common in the asymptomatic cohort. Overall, 35.2% of asymptomatic individuals and 10.8% of patients with benign disease were cytotoxin-associated gene A-negative (p<0.01). There was no significant association between immunoserotypes, ABO groups or benign gastroduodenal disease. All gastric malignancies (lymphoma and adenocarcinoma) were cytotoxin-associated gene A-positive but this was not significantly different from patients with benign disease. We found a higher prevalence of blood group A in patients with gastric malignancy than in the general population [47.6% versus 25%, p=0.037; RR=2.73 (1.04-7.16; 95% CI)].

CONCLUSIONS

The seroprevalence of H. pylori is moderately high in Lebanon. Phenotypic classification identifies a higher prevalence of Type I in symptomatic patients. A significant relationship between infection with a cytotoxin-associated gene A-positive strain in blood type A patients and the risk of gastric malignancy was noted.

Deterioration of gas exchange in patients with severe thrombotic thrombocytopenic purpura with respiratory failure during therapeutic plasma exchange

Therapeutic plasma exchange (TPE) is a procedure performed on patients suffering from various disorders, including thrombotic thrombocytopenic purpura (TTP). As we noted a frequent transient deterioration in respiratory function when the procedure was performed on intensive care unit (ICU) patients, we studied retrospectively the incidence of respiratory deterioration during and shortly after TPE and looked for a probable correlation with a change in the white blood cell (WBC) counts. Over a period of 10 months six patients with TTP, five of whom had parenchymal lung disease due to different medical reasons, underwent TPE. The oxygen saturation was measured continuously before, during, and after TPE; additionally, the WBC and differential counts were measured pre- and post-TPE. The ratio of the oxygen saturation by pulse oxymetry (SpO2) to the fraction of inspired oxygen (FiO2) was calculated before, during and after TPE. In these five patients with lung disorders, there was a consistent trend of a decreasing SpO2/FiO2 quotient during and within 2 h post TPE compared to the pre-TPE value. The decrease in SpO2/FiO2 range was 0.20-0.89 with an average of 0.56. In the same 5 patients there was an increase in the WBC count in the range of 2.3-19.7 x 10(9)/L with an average increase of 9.3 x 10(9)/L. The percent neutrophils of the total WBC counts also increased following most of the sessions, this increase was in the range of 1-15 % with an average of 7%. The effect of TPE on the SpO2/FiO2 ratio and the correlation to the WBC count and to a possible neutrophil activation has not been previously reported. We postulate that TPE can accentuate respiratory deterioration in patients with TTP who already have acute lung injury. This may be due to the priming and activation of the leukocytes that could lead to the release of cytokines and inflammatory mediators during the procedure. Thus, it is important to be aware of the possible deterioration in respiratory function and gas exchange while administering TPE to patients with pre-existing parenchymal lung injury.

An unusual case of hyperkalaemia-induced cardiac arrest in a paediatric patient during transfusion of a 'fresh' 6-day-old blood unit

A well-recognized complication of the transfusion of red blood cells (RBCs) is hyperkalaemia. This occurs in paediatric or adult patients receiving massive transfusion and can lead to cardiac arrest. Hyperkalaemia may follow the transfusion of 'stored' RBCs and/or haemolysed units, and depends on the quantity and rate of transfusion. We report on an unusual case of hyperkalaemia-induced cardiac arrest during transfusion of a 'fresh' blood unit. A 62-day-old baby girl was scheduled for a construction of a Blalock-Taussig shunt, after the completion of anastomosis, and upon release of vascular control, there was bleeding at the anastomotic site that was controlled with a suture placement. To compensate for the blood loss, a stat order was given for a push of 120 mL of RBCs over 10 min through the inferior vena cava central line. The blood unit was 6 days old and had been gamma-irradiated 48 h earlier. Shortly after the transfusion, the patient's electrocardiogram showed changes typical of hyperkalaemia; she then went into cardiac asystole. The blood unit potassium concentration was 55.3 mmol L-1, which flushed the atrioventricular node during transfusion. This is the first report of a high potassium level found in a 'fresh', less than 7 days old, nonhaemolysed RBC blood unit. The high concentration of potassium in this unit seems to be due to accelerated alterations of the RBC sodium/potassium adenosine triphosphatase pump (Na+/K+ pump), resulting in the release of intracellular potassium. This early and severe alteration of the pump and the unusually high potassium level may be due to as yet unexplained causes, warranting awareness, future investigation and routine saline washing of 'fresh' RBCs for paediatric patients who are candidates for central line transfusion.

Characterization of a novel hepatitis B virus mutant: demonstration of mutation-induced hepatitis B virus surface antigen group specific "a" determinant conformation change and its application in diagnostic assays

We report and characterize a novel mutant of the hepatitis B virus surface antigen (HBsAg). The mutant was isolated from a symptomatic patient who was found to be persistently positive for both HBsAg and anti-hepatitis B surface antibody (anti-HBs) and a long-lasting anti-HBc (core) IgM. Due to the unusual immune serological profile, polymerase chain reaction and sequencing were performed and revealed a genotype D mutant HBV (LBN). Aligned with known HBsAg sequences from GenBank, the LBN variant matched to consensus subtype ayw2 and revealed five mutation positions. Interestingly, none of the mutations was found within the group-specific "a" determinant region (124-147) and, specifically, two of the five mutations, T118K and P120Q, were located only a few amino acids adjacent to the 124-147 region. Using a panel of six monoclonal antibodies and vaccine raised human neutralizing antibodies, the recombinant wild-type HBsAg and the novel variant LBN HBsAg were investigated for their immunological reactivity. Vaccine raised human anti-HBs showed less reactivity to the variant LBN HBsAg than to wild-type HBsAg in enzyme immune assays. Furthermore, our observations demonstrate the influence of adjacent residues on the group-specific "a" determinant structural configuration; this resulted in severe antigenic changes of the immunodominant region as well as in the subtype serology. The importance of the variant LBN lies in the observation that mutations close to the "a" determinant can change the immunodominant region structure and therefore alter the group specific determinant antigenicity even though no mutations are present within this region. Hence, the classical definition of the "a" determinant cluster may need to be extended to cover a broader region to include the requirement of adjacent amino acids to support its conformation. In conclusion, by understanding the HBsAg major immunodominant region structure and by using a combination of antibodies with specificity covering all key mutation locations, maximal anti-HBs-based protection, and highly sensitive diagnostic assays can be achieved.

Thrombotic thrombocytopenic purpura in a case of scleroderma renal crisis treated with twice-daily therapeutic plasma exchange

We report the rare complication of thrombotic thrombocytopenic purpura (TTP) in an elderly patient with the uncommon scleroderma renal crisis (SRC) at the advanced age of 85 years. Initially, she was treated by standard daily one and a half plasma volume therapeutic plasma exchange (TPE), in combination with steroid therapy. Due to an unsatisfactory clinical response, she was consequently, treated by an intensive twice-daily one and a half plasma volume TPE regimen. Although there was an increase in the platelet count, a 7-day course of the intensive regimen did not elicit further propitious laboratory test results or a clinical improvement and the patient expired secondary to the pulmonary and cardiac conditions related to SRC. Intensive TPE administration has been advocated in few specific patients who are refractory to standard daily treatment. The unfavorable outcome in this case may be attributed to the multiple complications associated with her primary disorder. In conclusion, we observed intensive twice-daily TPE to increase temporarily the platelet count, but not to be of benefit in a patient with SRC and multiple organ failure. The two TPE regimens and outcomes are compared and the pathogenesis of TTP and scleroderma are discussed.

Thrombotic thrombocytopenic purpura in a patient with rheumatoid arthritis treated by plasmapheresis

Thrombotic thrombocytopenic purpura (TTP) is a multisystem disorder characterized by consumptive thrombocytopenia, microangiopathic hemolytic anemia, and neurologic symptoms. TTP is associated with many diseases and several therapeutic drugs. We report the rare case of a patient with rheumatoid arthritis who developed TTP that was not associated with drug therapy, 18 months after the onset of rheumatoid arthritis. She recovered from the TTP following daily sessions of therapeutic plasma exchange (TPE) with fresh frozen plasma replacement and glucocorticoid therapy. Recent pathogenic mechanisms are reviewed as they relate to von Willebrand factor. In this report of the rare association of TTP with rheumatoid arthritis, an immediate relationship is likely because both are of an immune nature. Awareness of the possible development of TTP in rheumatoid arthritis is important for early diagnosis and treatment.