Vacuolating toxin gene polymorphism among Helicobacter pylori clinical isolates and its association with m1, m2, or chimeric vacA middle types

BACKGROUND

Helicobacter pylori vacuolating cytotoxin encoded by vacA plays an essential role in H. pylori-related pathogenesis. Specific vacA alleles are believed to be associated with increased virulence. Association among vacA polymorphism, vacA middle genotypes, and various H. pylori-related diseases was thus investigated.

METHODS

Eighty-nine isolates from patients with various gastrointestinal diseases were examined for restriction fragment length polymorphism (RFLP) of the 2.0-kb polymerase chain reaction-amplified vacA middle region. Further genetic heterogeneity was assessed with ureA-ureB RFLP.

RESULTS

Twenty-eight distinct vacA RFLPs were seen among 89 isolates. Each pattern was associated with one specific vacA middle genotype. The association of specific RFLPs with certain clinical manifestations was noted among six common groups. Further RFLP analysis of the 2.4-kb ureA-ureB segment from isolates in four popular vacA RFLPs showed high genetic variation.

CONCLUSIONS

The vacA genetic polymorphism may be associated with different gastrointestinal diseases.

Patterns of HIV-1 evolution in individuals with differing rates of CD4 T cell decline

Evolution of HIV-1 env sequences was studied in 15 seroconverting injection drug users selected for differences in the extent of CD4 T cell decline. The rates of increase of either sequence diversity at a given visit or divergence from the first seropositive visit were both higher in progressors than in nonprogressors. Viral evolution in individuals with rapid or moderate disease progression showed selection favoring nonsynonymous mutations, while nonprogressors with low viral loads selected against the nonsynonymous mutations that might have resulted in viruses with higher levels of replication. For 10 of the 15 subjects no single variant predominated over time. Evolution away from a dominant variant was followed frequently at a later time point by return to dominance of strains closely related to that variant. The observed evolutionary pattern is consistent with either selection against only the predominant virus or independent evolution occurring in different environments within the host. Differences in the level to which CD4 T cells fall in a given time period reflect not only quantitative differences in accumulation of mutations, but differences in the types of mutations that provide the best adaptation to the host environment.

A conserved aspartate is essential for FAD binding and catalysis in the D-amino acid oxidase from Trigonopsis variabilis

To evaluate the possible contribution of Asp206 of Trigonopsis variabilis D-amino acid oxidase (DAO) to its flavin adenine dinucleotide (FAD) binding and catalytic function, six mutant enzymes were constructed by site-directed mutagenesis. Western immunoblot analysis revealed that a protein with an apparent molecular mass of about 39.2 kDa was present in the cell-free extracts of wild-type and mutant strains. Replacement of Asp206 with Leu, Gly, and Asn resulted in the loss of DAO activity and characteristic absorption spectrum for flavoenzyme, while the other mutant DAOs, Asp206Glu, Asp206Ser, and Asp206Ala, exhibited a similar spectral profile to that of wild-type enzyme and retained about 6-90% of the enzyme activity. These results suggested that Asp206 of T. variahilis DAO might play an important role in the binding of FAD.

Characterization of the C-terminal domain of Helicobacter pylori vacuolating toxin and its relationship with extracellular toxin production

Helicobacter pylori vacuolating cytotoxin (VacA) induces gastric epithelial necrosis. Its C-terminal domain is hypothesized to be responsible for extracellular translocation of the mature cytotoxin. In this study, genetic-structural properties of VacA C-terminal domain and the level of cytotoxin secretion were investigated. Sau3AI-HaeIII restriction fragment length polymorphism (RFLP) analysis of the 1.1-kb PCR-amplified vacA fragment revealed 14 distinct combined patterns among 87 clinical isolates. Of the 4 popular groups (A-a, A-b, A-f, and B-a), A-a strains produced a higher level of the VacA protein than A-b strains and than A-f strains (P < 0.05). Sequence analysis and secondary structure prediction supported a beta-barrel structure that might act as a selective export channel like Iga beta-core of IgA proteases. Sequence differences in the predicted beta-barrel were present among strains of different RFLPs.

Evidence of cranial artery ectasia in sickle cell disease patients with ectasia of the basilar artery

GOAL

To determine if children with sickle cell disease (SCD) and basilar artery ectasia show evidence of general arterial ectasia.

METHODS

A novel method was used to analyze the base images normally used to reconstruct a magnetic resonance angiogram (MRA). A signal intensity threshold was set empirically to exclude pixels from subcutaneous fat, then base images for each patient were evaluated for the number and relative size of vessel profiles. Data from three SCD patients, imaged before and after transfusion, were analyzed to determine sensitivity of the method to blood flow. We then compared 11 SCD patients with basilar ectasia to 11 age-matched SCD patients with a normal basilar, after excluding patients with clinical stroke.

FINDINGS

Before transfusion, patients have an apparent blood volume 48% higher than after (P<.001). Transfusion reduces apparent blood volume because flow rate is reduced by transfusion and MRA is flow-sensitive. But apparent blood volume was not significantly lower in any individual vessel size class, suggesting that fast flow simply increases vessel conspicuity. Patients with basilar ectasia have an apparent blood volume 62% higher than normal (P<.001). Although this could be due to faster blood flow, apparent blood volume was higher specifically in vessels > or =2 mm in diameter (P<.001), suggesting that small arteries can become generally ectatic in patients with basilar ectasia.

CONCLUSIONS

Basilar ectasia is associated with an increased blood flow rate, generalized arterial ectasia, or both phenomena. This suggests that basilar volume measurements may supplement blood flow velocity measurements as an indicator of stroke risk.

Allergic diseases in preschool children in Taichung City

The occurrence of allergic diseases in preschool children was studied on the basis of a questionnaire sent to the parents of 5,408 kindergarten students, 3 to 6 years of age, in Taichung City. The overall response rate was 81% and included 2311 (52.8%) boys and 2062 (47.2%) girls. Allergic diseases had been recognized in 34.6% of the children. The cumulative (lifetime) prevalence of bronchial asthma (BA), allergic rhinitis (AR), atopic eczema (AE), and urticaria were 9.4%, 26.4%, 6.6% and 6.8%, respectively. The current (past 12 months) prevalence of BA, AR, and AE was 6.7%, 14.8%, and 3.5%, respectively. BA and AR occurred more frequently in boys than in girls (P < 0.001); no significant difference was found between boys and girls in AE (P = 0.328). There were statistically significant relationships between positive family history and BA, AR and AE (P < 0.001). In conclusion, allergic diseases constitutes an important health problem for pre-school students in Taichung City.

Measuring individual differences in change with multidimensional Rasch models

Item response models have been developed to explore change measurement, including those proposed by Fischer and his colleagues (e.g., Fischer & Pazer, 1991; Fischer & Ponocny, 1994), Andersen (1985) and Embretson (1991). In this article, we propose another multidimensional Rasch model, the multidimensional random coefficient multinomial logit (MRCML) model (Adams, Wilson, & Wang, 1997). All these models are briefly reviewed and compared. The MRCML can be applied to not only polytomous items but also investigation of variations in item difficulties. Based on variations in difficulties across occasions and items, five kinds of models are proposed. Some simulation studies were conducted to examine parameter recovery of the MRCML model under various testing situations. All the parameters were recovered very well. A real data set was analyzed to show applications of the MRCML to measuring individual differences in change.

Rasch analysis of distractors in multiple-choice items

In order to apply the Rasch model to multiple-choice items, incorrect responses to distractors are usually aggregated to a single category. In doing so, information of individual distractors disappears. In this paper, a Rasch-type analysis is proposed where one parameter is assigned to each distractor. The information is thus preserved. The proposed distractor model can be applied to investigate the performance of distractors, which is useful for item revision. This model is a necessary condition of the Rasch model, that is, fitting the distractor model will fit the Rasch model, but not vice versa. The results of a small simulation study show that parameter recovery of the distractor model is very satisfactory. A real data set of twenty multiple-choice items was analyzed. Some items were found to fit the Rasch model rather than the distractor model. It is this diagnostic value that makes the distractor model suitable for multiple-choice items.

T2-weighted MR imaging for hepatic hemangiomas: comparison of breath-hold and non-breath-hold turbo spin-echo pulse sequences with phased-array multicoil

BACKGROUND

We compared T2-weighted and heavily T2-weighted breath-hold turbo spin-echo (TSE) sequences with T2-weighted non-breath-hold TSE sequence to evaluate hepatic hemangiomas on magnetic resonance (MR) with a phased-array multicoil.

METHODS

Twenty-two patients with 27 hemangiomas were studied at 1.0-T scanner by using T2-weighted and heavily T2-weighted breath-hold TSE sequences (18 s each) and non-breath-hold T2-weighted TSE sequences with use of a phased-array multicoil. Images were quantitatively analyzed for tumor-to-liver signal-difference-to-noise ratios (SD/Ns) and tumor-to-liver signal intensity ratios (T/Ls) and qualitatively analyzed for tumor conspicuity and motion-induced image artifacts.

RESULTS

Quantitatively, T2-weighted breath-hold TSE images showed the highest SD/Ns among the three sequences, although the differences from the heavily T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were not statistically significant (p = 0.61 and 0.06, respectively). Heavily T2-weighted breath-hold TSE images showed the highest T/Ls among the three sequences. The differences from the T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were statistically significant (p < 0.001). Qualitatively, breath-hold TSE images were superior to non-breath-hold TSE images in terms of tumor conspicuity (p < 0.01) and motion artifacts (p < 0.01).

CONCLUSION

T2-weighted breath-hold TSE sequence is superior to T2-weighted non-breath-hold TSE sequence in the evaluation of hepatic hemangiomas on MR with a phased-array multicoil.

The serum selenium concentrations in children and young adults: a long-term study during the Finnish selenium fertilization programme

OBJECTIVE

To investigate the effects of the Finnish nationwide selenium (Se) fertilization programme on the Se status of the population.

DESIGN AND SUBJECTS

Serum Se concentrations from 1985-1992 from 1568 healthy children and young adults in southwestern Finland were determined using direct electrothermal atomic absorption spectrometry.

RESULTS

The mean concentration in young adults increased from 1.04 micromol/L in 1985 to 1.59 micromol/L in 1990. Children younger than 15 y had lower concentrations than adults, with an increase from 0.87 micromol/L in 1985 to 1.31 micromol/L in 1990. The younger the children, the lower the Se concentrations tended to be. At the age of about seven months no significant difference was noted between breast-fed and formula-fed infants. From 1991, when the amount of Se added to fertilizers was reduced and less foreign high-Se cereal was imported, the Se concentrations decreased in all age groups.

CONCLUSIONS

The nationwide Se supplementation programme has succeeded in elevating the Se intake and the serum Se concentrations in the Finnish population.

Differential expression and function of L-selectin on CD56bright and CD56dim natural killer cell subsets

NK cells are the first line of defense against foreign cells, virally infected cells, and tumors. The mechanisms whereby NK cells accumulate in extralymphoid sites in response to pathogenic stimuli are not well understood. The L-selectin adhesion molecule (CD62L) plays a primary role in mediating the initial interaction of leukocytes with vascular endothelium, a crucial step in the extravasation of immune effector cells into tissues. In this report, we show L-selectin to be uniquely expressed on a subset of resting human NK cells (CD56bright). Notably, CD56bright NK cells expressed L-selectin at a higher density than all other peripheral blood leukocytes. NK activation by PMA, IL-2, IL-15, or TGF-beta down-regulated L-selectin on the CD56bright subset, while increased L-selectin levels were observed in both the CD56bright and CD56dim NK subsets in response to IL-12, IL-10, or IFN-alpha. Moreover, CD56bright NK cells bound with high efficiency to physiologic L-selectin ligands on peripheral lymph node high endothelial venules (HEV). In sharp contrast, CD56dim NK cells adhered poorly to HEV and were predominantly L-selectin- or expressed L-selectin only at low density. In CD56bright cells and a subpopulation of CD56dim cells, L-selectin ligation by mAb cross-linking activated lymphocyte function-associated Ag 1 (LFA-1), a second adhesion molecule required for leukocyte extravasation. LFA-1 was expressed on both NK subsets, although its density was constitutively higher on CD56dim cells. Taken together, evidence of differential expression of L-selectin and LFA-1 on CD56bright and CD56dim NK subsets strongly suggests unique migratory properties and functions of these cells during the early immune response to foreign pathogens.

Vacuolating toxin production in clinical isolates of Helicobacter pylori with different vacA genotypes

A vacuolating cytotoxin encoded by vacA in Helicobacter pylori is known as a potential virulent determinant. The relationship between different vacA alleles, vacuolating ability, and H. pylori-related diseases was investigated. Genetic analysis of 119 isolates from Taiwanese patients revealed that 104 strains were s1a/m2, 13 strains were characterized as the s1a/m1T type, which was more homologous to the s1a/m1 strains, and 2 were characterized as the s1a/m1Tm2 chimeric type. Production of high-grade cytotoxin among 11 strains with s1a/m1T was higher (72.7%) than among 66 strains with s1a/m2 (21.2%) (P < .01). Peptic ulcer occurred in 76.9% of 13 patients with s1a/m1T strains compared with 46.2% of 104 patients with s1a/m2 strains (P < .05). These results suggest that s1a/m1T strains are associated with increased cytotoxic activity and higher ulcer prevalence than are s1a/m2 strains.

Abnormalities of the central nervous system in very young children with sickle cell anemia

OBJECTIVE

To determine whether abnormalities of the CNS are present in very young children with sickle cell anemia.

STUDY DESIGN

Thirty-nine children with hemoglobin SS between the ages of 7 and 48 months were examined with magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). No child had a history of clinical stroke, although 3 had a history of seizures (2 neonatal). Twenty-one patients underwent developmental testing with the Bayley or McCarthy Scales.

RESULTS

The overall prevalence of CNS abnormalities in asymptomatic children was 4 of 36 (11%, confidence interval 3, 26%). One patient had a silent infarct observed on MRI and a stenotic lesion on MRA; 3 other patients had stenotic lesions on MRA. The 3 patients who had a history of seizures all had lesions consistent with infarcts on MRI. Of the asymptomatic patients who had psychometric testing, 1 of 18 was developmentally delayed. One of 3 with a history of seizures had mild developmental delay.

CONCLUSIONS

Very young children with sickle cell anemia (and no history of clinical stroke) have infarction in the brain and/or stenosis of major cerebral arteries, similar to those reported in older children. These findings indicate a need for larger studies to define the incidence of CNS lesions in this age group and to determine the need for early therapeutic intervention to prevent CNS sequelae of sickle cell disease.

Malignant infantile osteopetrosis: otolaryngological complications and management

OBJECTIVES

To inform otolaryngologists about upper airway obstruction requiring tracheotomy and other otolaryngological manifestations of malignant infantile osteopetrosis (MIOP) and to discuss pathophysiological features, management, and new treatment strategies in MIOP.

DESIGN

Ongoing case series combined with a retrospective chart review.

SETTING

International tertiary pediatric hospital.

INTERVENTIONS

Patients with MIOP were initially referred for treatment and routine follow-up. Tracheotomy was performed to manage obstructive sleep apnea. Audiograms were also performed at regular intervals.

RESULTS

The records of 9 patients were examined. The otolaryngological findings of hearing loss, obstructive sleep apnea (sometimes requiring tracheotomy), otitis media, and chronic osteomyelitis with facial fistulas were identified.

CONCLUSIONS

Osteopetrosis is a rare condition caused by a failure of the osteoclast to resorb bone. This results in thickened dense, deformed, and easily fractured bone. As a result, growth failure, anemia, hypoplastic dentition, chronic infections, facial fistulas, blindness, hearing loss, nasal congestion, and upper airway obstruction may occur. The management of otolaryngological problems in a child with osteopetrosis is an important component in comprehensive care. To our knowledge, this study represents the largest case series of MIOP in the otolaryngology literature.

Quantitative MRI of the brain in children with sickle cell disease reveals abnormalities unseen by conventional MRI

Conventional MRI (cMRI) has shown that brain abnormalities without clinical stroke can manifest in patients with sickle cell disease (SCD). We used quantitative MRI (qMRI) and psychometric testing to determine whether brain abnormalities can also be present in patients with SCD who appear normal on cMRI. Patients 4 years of age and older with no clinical evidence of stroke were stratified by cMRI as normal (n = 17) or abnormal (n = 13). Spin-lattice relaxation time (T1) of gray and white matter structures was measured by the precise and accurate inversion recovery (PAIR) qMRI method. Patient cognitive ability was assessed with a standard psychometric instrument (WISC-III or WISC-R). In all 30 patients with SCD, qMRI T1 was lower than in 24 age- and race-matched controls, in cortical gray matter (P < .0006) and caudate (P < .0009), as well as in the ratio of gray-to-white matter T1 (P < .008). In the 17 patients who were shown to be normal by cMRI, qMRI T1 was still lower than in controls, in both cortical gray matter (P < .02) and caudate (P < .004). Histograms of voxel T1 show that the proportion of voxels with T1 values intermediate between gray and white matter (ie, consistent with encephalomalacia) was 9% higher than controls in patients shown to be normal by cMRI (P < .05) and 15% higher than controls in patients shown to be abnormal by cMRI (P < .0005). The full scale intelligence quotient (FSIQ) of all patients with SCD was 75, compared to the FSIQ of 88 in a historical control group of patient siblings (P < .001). The FSIQ of patients shown to be normal by cMRI was 79, significantly lower than the FSIQ of patient siblings (P < .04). The FSIQ of 71 in patients shown to be abnormal by cMRI was significantly lower than both the patient siblings (P < .005) and the patients shown to be normal by cMRI (P < .04). Patients shown to be abnormal by cMRI scored lower than patients shown to be normal by cMRI, specifically on the subtests of vocabulary (P = .003) and information (P = .03). Cognitive impairment is thus significant, even in patients with SCD who were shown to be normal by cMRI, suggesting that cMRI may be insensitive to subtle neurologic damage that can be detected by qMRI. Because cognitive impairment can occur in children normal by cMRI, our findings imply that prophylactic therapy may be needed earlier in the course of SCD to mitigate neurologic damage.

Fever-range hyperthermia enhances L-selectin-dependent adhesion of lymphocytes to vascular endothelium

The L-selectin leukocyte adhesion molecule plays an important role in controlling leukocyte extravasation in peripheral lymph nodes and at sites of tissue injury or infection. Although febrile responses during infection and inflammation are associated with enhanced immune activity, the contribution of fever-range temperatures to controlling lymphocyte recruitment to tissues has not been previously examined. In this report we provide evidence that direct exposure of lymphocytes to fever-range temperatures (38-41 degrees C) in vitro for 9 to 24 h resulted in a >100% increase in L-selectin-dependent adhesion of these cells to lymph node high endothelial venules (HEV). Moreover, culture of lymphocytes under hyperthermia conditions markedly enhanced the ability of these cells to traffic in an L-selectin-dependent manner to peripheral lymph nodes, mesenteric lymph nodes, and Peyer's patches. In contrast, febrile temperatures did not increase LFA-1 function as assessed by measuring lymphocyte adhesion to ICAM-1-3T3 transfectants. Fever-range hyperthermia further did not increase L-selectin surface density on lymphocytes or L-selectin-dependent recognition of soluble carbohydrate substrates; however, a marked increase in ultrastructural immunogold-labeling of L-selectin was observed in response to thermal stimuli. These results suggest that elevated temperatures enhance L-selectin adhesion and/or avidity through the regulation of L-selectin conformation or organization in the plasma membrane. Finally, the observed thermal effects on L-selectin adhesion were attributed to soluble factors in the conditioned medium of heat-treated cells. Taken together, these data provide new insight into the potential physiologic role of the febrile response in enhancing lymphocyte recruitment to tissues through the regulation of L-selectin adhesion.

Thrombopoietin level in young patients is related to megakaryocyte frequency and platelet count

PURPOSE

To examine the relationships among platelet counts, bone marrow megakaryocyte frequency, and circulating thrombopoietin (TPO) levels.

PATIENTS AND METHODS

TPO levels in 17 children and one young adult with chronic or recurrent thrombocytopenia were measured by ELISA and megakaryocyte frequency was analyzed by light microscopy. Three groups of patients were studied: Group I patients had aplastic anemia and absent or decreased megakaryocytes; Group II patients had intermittent periods of chemotherapy-induced thrombocytopenia; and Group III patients had normal or increased megakaryocytes. Controls consisted of 77 healthy adults.

RESULTS

Patients in Group I had markedly increased TPO levels compared to normal controls. Their levels were significantly different (p = 0.03) from those of patients in Group III. The latter had normal or only mildly increased TPO levels except for one patient with myelodysplastic syndrome. Patients in Group II had markedly elevated TPO levels. After their bone marrow and platelet counts recovered from chemotherapy, their TPO levels decreased. In all three groups, a transient increase in platelet count (e.g., after platelet transfusion or anti-D immune globulin therapy) was associated with a moderate decrease in TPO.

CONCLUSIONS

From this study, three conclusions can be made: 1) TPO levels are inversely related to megakaryocyte frequency; 2) platelet counts have a modest influence on TPO level; and 3) TPO levels may have clinical utility in diagnosis and management and further our understanding of the pathobiology of the disorders that cause thrombocytopenia.

Myelodysplastic syndrome in children: differentiation from acute myeloid leukemia with a low blast count

To evaluate diagnostic criteria, disease characteristics, and the clinical course of pediatric myelodysplastic syndrome (MDS), we reviewed 327 consecutive cases diagnosed with de novo acute myeloid leukemia (AML) or MDS at St Jude Children's Research Hospital between February 1980 and January 1993. Among 49 cases with <30% marrow blasts (consistent with FAB criteria and common diagnostic practice for MDS), eight had karyotypes associated with de novo AML (four with t(8;21)(q22;q22) and one each with inv(16)(p13q22), t(11;17)(q23;q21), t(9;11)(p22;q13), and i(1)(ql0)). We termed these cases AML with a low blast count (AML-LBC) and compared their clinical and morphologic features with those of the remaining 41 cases. AML-LBC cases had little or no hematopoietic dysplasia. MDS cases consisted of refractory anemia (RA, n=6), RA with ring sideroblasts (n=2), RA with excess blasts (RAEB, n=4), RAEB in transformation (n=14), and chronic myelomonocytic leukemia (n=15). Most had moderate/severe or multilineage hematopoietic dysplasia, with significantly higher dysplasia scores than AML-LBC cases (P=0.007). Only 30% of patients with MDS achieved complete remission (CR) after two cycles of AML-directed therapy, compared with 88% of patients with AML-LBC (P=0.0001); MDS patients tended to experience prolonged severe cytopenias with chemotherapy. The 4-year survival for MDS patients was 23% +/- 7% (s.e.), vs 50% +/- 18% (s.e.) for AML-LBC (P=0.048). AML-LBC patients frequently had chloromas; none were seen in MDS patients. We conclude that the 30% blast threshold is ineffective for separation of AML and MDS in pediatric patients, and that genetic data should be included in this decision process. AML-LBC, defined by <30% blasts in bone marrow and cyto- (or molecular) genetic abnormalities associated with de novo AML, and characterized by absent or mild marrow dysplasia, is biologically and clinically distinct from MDS and should be treated as de novo AML. Outcome in pediatric MDS remains poor, and new treatment strategies are needed for these patients.

Expression, purification, and characterization of a murine CD4 fragment containing the first two N-terminal domains

CD4 is a membrane glycoprotein on T lymphocytes that binds to the same peptide:major histocompatibility complex (MHC) class II molecules recognized by the antigen-specific T cell receptor (TcR). Recent evidence supports the importance of coaggregation of CD4 and TcR for effective T cell activation. Here, we report that a transfected Chinese hamster ovary (CHO) cell line expressing a murine CD4 fragment containing the first two N-terminal domains secretes both monomeric molecules and disulfide-linked multimers. Elimination of the predicted N-linked glycosylation site at residue 161 that is next to the fourth cysteine does not affect the formation of interchain disulfide bonds. N-Terminal amino acid sequencing of the purified CD4 fragment demonstrates that the leader signal sequence is properly cleaved off the expressed protein. Circular dichroism studies suggest that both monomeric and disulfide-linked proteins are folded as primarily beta-sheet.

Successful newborn sickle cell trait counseling program using health department nurses

Every year more than 50,000 infants with sickle cell trait are identified through newborn screening programs. An infant with trait provides a "genetic window" into a family that may be at risk for having a child with sickle cell disease. No national standards have been established for newborn trait follow-up and family counseling. In the United States, counseling to families having an infant with trait is usually very limited in scope and, in many cases, nonexistent. In West Tennessee, the Mid-South Sickle Cell Center (MSSCC) and the Department of Health have jointly developed an effective, practical, and affordable trait counseling program. A five-step counseling protocol, an accompanying counseling manual, a documentation checklist, and a fact sheet for parents were developed to support trait counselling. By training and using health department nurses, this program has provided counseling to a large percentage of families in which an infant tests positive for sickle cell trait.

Orbital compression syndrome in sickle cell disease

BACKGROUND

Orbital complications are an uncommonly reported finding in sickle cell disease.

METHODS

The authors review the reported orbital manifestations of sickle cell disease and discuss a patient with hemoglobin sickle beta(0) thalassemia in whom rapidly progressive bilateral orbital compression developed.

RESULTS

Computed tomography of the orbits in a patient with fever, headache, orbital swelling, and optic nerve dysfunction displayed bilateral superior subperiosteal cystic masses. Surgical exploration showed bilateral liquefied hematomas, which were evacuated. Recovery was complete 13 days after surgery. A mild recurrence 14 months later resolved with conservative treatment. The literature contains 11 reports of 16 young patients with sickle cell disease (15 sickle cell disease [Hb SS] and 1 hemoglobin sickle cell disease [Hb SC]) with rapidly developing findings ranging from frontal headache, fever, and eyelid edema to bilateral complete orbital compression syndrome. Including our patient, 60% had orbital hemorrhage on computed tomography. Ten of 12 patients tested were found to have orbital bone marrow infarctions. Sixteen of 17 patients had complete recovery; 13 were treated conservatively and 4 surgically. Only 2 of 17 had recurrence.

CONCLUSIONS

Orbital complications in sickle cell disease are unusual manifestations in which a vaso-occlusive process in the marrow space around the orbit results in frontal headache, fever, eyelid edema, and often orbital compression syndrome. Subperiosteal hematomas are common and appear to result from bone marrow infarctions. Appropriate management requires a thorough evaluation to exclude other hemorrhagic, infectious or neoplastic processes, as well as vigilant ophthalmic monitoring. Supportive care is effective, unless optic nerve dysfunction or large hematomas are present, which would indicate that surgical evacuation is warranted to prevent loss of vision and to speed recovery.

Genetic analysis of the cytotoxin-associated gene and the vacuolating toxin gene in Helicobacter pylori strains isolated from Taiwanese patients

OBJECTIVE

Two virulence factors encoded by the cytotoxin-associated (cagA) gene and the vacuolating toxin (vacA) gene of Helicobacter pylori are known to be associated with gastroduodenal pathologic conditions. In this report, nucleotide sequence of cagA and vacA and the serum antibody response to the CagA antigen in H. pylori isolates from Taiwanese patients were studied.

METHOD

cagA and vacA were characterized in 173 H. pylori strains by polymerase chain reaction and DNA hybridization analyses. The presence of serum IgG antibodies against CagA was assessed by Helico-blot Western blot system. Sequence analysis of polymerase chain reaction-amplified vacA and cagA was performed for two strains.

RESULTS

cagA was detected in all the isolates with peptic ulcers and gastric cancer. Of 54 strains with non-ulcer dyspepsia, 51 were found to be cagA+. Serum antibodies to CagA were detected for 99.2% of cagA+ strains compared with 0% of strains lacking cagA. vacA was detected in all isolates. Sequence analysis of vacA and cagA indicated that sequences of two Taiwanese strains were closely related to each other (95.9% and 97% nucleotide identity, respectively) but less homologous to the published strains (90.9% and 91.4% mean nucleotide sequence identity, respectively).

CONCLUSIONS

The strong association (98%) of cagA+ strains with Taiwanese patients suggests that the cagA+ phenotype could not be used as a single marker of high-risk patients in Taiwan. Moreover, sequence analysis indicates that Taiwanese strains contain different genetic sequences from those in other geographic regions.

Recurrent Streptococcus pneumoniae sepsis in children with sickle cell disease

Streptococcus pneumoniae sepsis is the most common invasive infection among patients with sickle cell disease. The risk of a recurrent episode of sepsis and subsequent death in those patients who have had a previous septic event is much higher. Patients with sickle disease who have had pneumococcal sepsis should continue penicillin prophylaxis indefinitely and should not be candidates for out-patient management of febrile episodes.

Nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae in children with sickle cell disease

OBJECTIVE

We studied the prevalence of nasopharyngeal (NP) carriage, antimicrobial susceptibilities, and serotypes of Streptococcus pneumoniae (SP) in children with sickle cell disease (SCD) in the Mid-South. In addition, we examined risk factors for NP carriage of penicillin-resistant SP (PRSP).

STUDY DESIGN

Between July 1994 and December 1995, we obtained NP cultures from 312 children with SCD followed at the Mid-South Sickle Cell Center, 208 (67%) of whom were receiving penicillin prophylaxis.

RESULTS

Among the 312 patients, colonization with SP occurred in 42 (13%), 30 (71%) of whom were receiving penicillin prophylaxis. Twenty-three of the 42 SP isolates (55%) were resistant to penicillin; 5 of the 23 (22%) were highly resistant. PRSP organisms were also resistant to cefotaxime (43%), trimethoprim-sulfamethoxazole (57%), and erythromycin (22%). Serotypes 6A, 6B, 14, 19A, and 23F accounted for 19 (90%) of 21 resistant strains. Children who were treated with antibiotics during the preceding month were more likely to carry PRSP than children who were not treated.

CONCLUSIONS

There is a high prevalence of NP carriage of PRSP in children with SCD in the Mid-South, which raises concerns regarding the continued effectiveness of penicillin prophylaxis in these children. Further studies on the antimicrobial susceptibilities of resistant organisms and the relationship between NP carriage of SP and invasive disease are needed before developing new recommendations for prophylaxis and treatment.

Serotype-specific immunoglobulin G antibody responses to pneumococcal polysaccharide vaccine in children with sickle cell anemia: effects of continued penicillin prophylaxis

OBJECTIVES

(1) To determine serotype-specific IgG antibody responses to reimmunization with pneumococcal polysaccharide vaccine at age 5 years in children with sickle cell anemia and (2) to determine whether continued penicillin prophylaxis had any adverse effects on these responses.

STUDY DESIGN

Children with sickle cell anemia, who had been treated with prophylactic penicillin for at least 2 years before their fifth birthday, were randomly selected at age 5 years to continue penicillin prophylaxis or to receive placebo treatment. These children had been immunized once or twice in early childhood with pneumococcal polysaccharide vaccine and were reimmunized at the time of randomization.

RESULTS

Serotype-specific IgG antibody responses to reimmunization varied according to pneumococcal serotype but in general were mediocre or poor; the poorest response was to serotype 6B. The antibody responses were similar in subjects with continued penicillin prophylaxis or placebo treatment, and in subjects who received one or two pneumococcal vaccinations before reimmunization. The occurrence of pneumococcal bacteremia was associated with low IgG antibody concentrations to the infecting serotype.

CONCLUSIONS

Reimmunization of children with sickle cell anemia who received pneumococcal polysaccharide vaccine at age 5 years induces limited production of serotype-specific IgG antibodies, regardless of previous pneumococcal vaccine history. Continued penicillin prophylaxis does not interfere with serotype-specific IgG antibody responses to reimmunization.