Crystal structure of the human prion protein reveals a mechanism for oligomerization

The pathogenesis of transmissible encephalopathies is associated with the conversion of the cellular prion protein, PrP(C), into a conformationally altered oligomeric form, PrP(Sc). Here we report the crystal structure of the human prion protein in dimer form at 2 A resolution. The dimer results from the three-dimensional swapping of the C-terminal helix 3 and rearrangement of the disulfide bond. An interchain two-stranded antiparallel beta-sheet is formed at the dimer interface by residues that are located in helix 2 in the monomeric NMR structures. Familial prion disease mutations map to the regions directly involved in helix swapping. This crystal structure suggests that oligomerization through 3D domain-swapping may constitute an important step on the pathway of the PrP(C) --> PrP(Sc) conversion.

Identification of DNA variants in the SNAP-25 gene and linkage study of these polymorphisms and attention-deficit hyperactivity disorder

The gene for the synaptic vesicle docking fusion protein, synaptosomal-associated protein of 25 kDa (SNAP-25), has been implicated in the etiology of attention-deficit hyperactivity disorder (ADHD) based on the mouse mutant strain coloboma. This neutron-irradiation induced mouse strain is hemizygous for the deletion of the SNAP-25 gene and displays spontaneous hyperactivity that is responsive to dextroamphetamine. Because of these characteristics, this strain has been suggested to be a mouse model for ADHD. We identified using single stranded conformational polymorphism analysis (SSCP) four DNA sequence variants in the 3' untranslated region of the human SNAP-25 gene. We searched for polymorphisms in the 3' untranslated region because the intron/exon structure of this gene has not yet been determined. We tested for linkage of this gene and ADHD using two of the identified polymorphisms that change a restriction enzyme recognition site. We examined the transmission of the alleles of each of these polymorphisms and the haplotypes of both polymorphisms using the transmission disequilibrium test in a sample of 97 small nuclear families consisting of a proband with ADHD, their parents, and affected siblings. We observed biased transmission of the haplotypes of the alleles of these two polymorphisms. Our findings are suggestive of a role of this gene in ADHD.

Hypocalcaemia and vitamin D deficiency: an important, but preventable, cause of life-threatening infant heart failure

BACKGROUND

In recent large paediatric cardiomyopathy population studies from North America and Australia, vitamin D deficiency was not identified as a cause of infant heart failure. However, rickets is resurgent in developed countries.

OBJECTIVE

To review the prevalence of this cardiomyopathy in paediatric cardiology units of southeast England and determine the prognosis.

METHODS AND RESULTS

A retrospective review from 2000 to 2006 in southeast England. Sixteen infants (6 Indian subcontinent, 10 black ethnicity) were identified: median (range) age at presentation was 5.3 months (3 weeks-8 months). All had been breast fed. Ten presented at the end of the British winter (February-May). Median shortening fraction was 10% (range 5-18%) and median left ventricular end diastolic dimension z score was 4.1 (range 3.1-7.0). Six had a cardiac arrest; three infants died. Eight were ventilated, two required mechanical circulatory support and 12 required intravenous inotropic support. Two were referred for cardiac transplantation. Median (range) of biochemical values on admission was: total calcium 1.5 (1.07-1.74) mmol/l; alkaline phosphatase 646 (340-1057) IU/l; 25-hydroxyvitamin D 18.5 (0-46) nmol/l (normal range >35) and parathyroid hormone 34.3 (8.9-102) pmol/l (normal range <6.1). The clinical markers and echocardiographic indices of all survivors have improved. The mean time from diagnosis to achieve normal fractional shortening was 12.4 months.

CONCLUSIONS

Vitamin D deficiency and consequent hypocalcaemia are seen in association with severe and life-threatening infant heart failure. That no infant or mother was receiving the recommended vitamin supplementation highlights the need for adequate provision of vitamin D to ethnic minority populations.

Glutathione in health and disease: pharmacotherapeutic issues

OBJECTIVE

To review the current research and importance of glutathione (GSH) therapy in health and disease and to provide a basic overview of the widespread use and interest in this compound.

DATA IDENTIFICATION

Articles were obtained via a MEDLINE search of the term glutathione in conjunction with specific disease states mentioned, and via extensive review of references found in articles identified by computer search.

STUDY SELECTION

Emphasis was placed on the most recent research, human research, and in discussing multiple disease states.

DATA EXTRACTION

The literature was reviewed for methodology, quality, and practical aspects of interest to clinical pharmacists.

DATA SYNTHESIS

GSH is a tripeptide of extreme importance as a catalyst, reductant, and reactant. It continues to be investigated in diverse areas such as acute respiratory distress syndrome, toxicology, AIDS, aging, oncology, and liver disease. Despite the widespread clinical interest in GSH, we were not able to identify an in-depth review of this compound in the pharmacy literature.

CONCLUSIONS

The list of potential indications for modulation of GSH is extensive and broad. This review introduces clinicians to what GSH is, its basic chemistry, and some areas of active research.

Haplotype study of three polymorphisms at the dopamine transporter locus confirm linkage to attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is often treated using methylphenidate, a psychostimulant that inhibits the dopamine transporter. This led E.H. Cook and colleagues to consider the dopamine transporter locus (DAT1) as a primary candidate gene for ADHD. That group reported a significant association between ADHD and the 480-base pair (bp) allele of the variable number of tandem repeats (VNTR) polymorphism located in the 3' untranslated region of the DAT1 gene. This association was later replicated in additional studies.

METHODS

The DAT1 gene has additional common polymorphisms in intron 9 and exon 9. We investigated the possibility of linkage of DAT1 and ADHD using the VNTR polymorphism and two additional common polymorphisms in 102 nuclear families with an ADHD proband. Using the transmission disequilibrium test, we examined the transmission of the alleles of each of these polymorphisms, as well as the haplotypes of the polymorphisms.

RESULTS

We did not observe significant evidence for the biased transmission of the alleles of either the VNTR or the additional two polymorphisms when examined individually, although there was a trend for the biased transmission of the 480-bp allele of the VNTR. When we examined the haplotypes of the three polymorphisms we found significant evidence for biased transmission of one of the haplotypes containing the 480-bp VNTR allele. We also genotyped six additional DNA sequence variants of the DAT1 gene. However, these variants were not sufficiently polymorphic in our sample to be informative. Two of the DNA variants that result in an amino acid change, Ala559Val and Glu602Gly, were not observed in our sample.

CONCLUSIONS

Our results support previous findings of an association between the DAT1 gene and ADHD.

Myogenin and MyoD1 expression in paediatric rhabdomyosarcomas

The diagnosis of paediatric solid tumours is often based on small tissue needle biopsies in which many different entities demonstrate a "small round cell tumour" phenotype and in which there may be insufficient tissue to allow the interpretation of diagnostic architectural features, which may be present in larger specimens. Therefore, the extensive use of a panel of immunohistochemical markers is part of the routine handling and investigation of such biopsies to reach a definite diagnosis. However, in some cases the morphological and routine immunohistochemical findings may be insufficient for a precise diagnosis or they may be difficult to interpret in the given clinical context. Although many paediatric tumours exhibit characteristic chromosomal translocations with resultant specific fusion transcripts, these require molecular methods for their detection, usually on fresh tissue samples, which may not always be available. As more immunohistochemical markers become available, more precise diagnosis on such small biopsies may be possible. This review examines the use of the immunohistochemical markers, MyoD1 and myogenin, in the diagnosis of paediatric rhabdomyosarcoma, including its subtypes.

Chromium picolinate toxicity

OBJECTIVE

To describe a case of toxicity secondary to chronic ingestion of 6-12 times the recommended daily allowance of over-the-counter (OTC) chromium picolinate.

CASE SUMMARY

A 33-year-old white woman presented with weight loss, anemia, thrombocytopenia, hemolysis, liver dysfunction (aminotransferase enzymes 15-20 times normal, total bilirubin 3 times normal), and renal failure (serum creatinine 5.3 mg/dL; blood urea nitrogen 152 mg/dL). She had ingested chromium picolinate 1200-2400 microg/d for the previous 4-5 months to enhance weight loss. The patient had chromium plasma concentrations 2-3 times normal. Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome were ruled out by clinical findings, peripheral blood smears, and a bone marrow biopsy. The patient was managed with supportive measures and received blood product transfusions and hemodialysis. Hemolysis stabilized and liver function improved over 6 days. Liver function returned to normal prior to discharge. Renal function began to return on day 12 and her serum creatinine on discharge was 1.3 mg/dL. One year later, all laboratory values were within normal limits.

DISCUSSION

Trivalent chromium is an essential trace element that is considered safe when ingested in normal quantities. Trivalent chromium compounds are used by patients to enhance weight loss, increase lean body mass, and/or improve glycemic control. Information regarding the toxicity of chromium picolinate is limited.

CONCLUSIONS

Chromium supplements may cause serious renal impairment when ingested in excess. Medication histories should include attention to the use of OTC nutritional supplements often regarded as harmless by the public and lay media.

Gastric Bypass and Vertical Banded Gastroplasty- a Prospective Randomized Comparison and 5-Year Follow-up

BACKGROUND: a prospective randomized study was undertaken to compare the outcome of vertical banded gastroplasty (VBG) and gastric bypass (GBP) in patients with clinically severe obesity. METHODS: eligibility criteria included Class IV obesity, < 50 years old and a history of at least one attempt of non-operative weight loss. Patients were managed conservatively for 3 months prior to surgery. Patients were followed post-operatively and monitored for early and late complications and their weight loss outcome for up to 5 years. RESULTS: 44 patients were recruited. Two patients withdrew within 4 weeks and were excluded. Twenty subjects had a GBP and 22 a VBG. There were no significant differences with respect to age, gender, maximum or pre-operative weight between the groups (p > 0.05). Patients who underwent GBP demonstrated significantly greater post-operative weight loss (p < 0.05) which was apparent from 6 months onwards. There were no deaths, pulmonary emboli, post-operative leaks or wound dehiscence. There were no instances of staple-line disruption. Symptomatic ulcer disease, confirmed endoscopically, developed in 25% of GBP patients. Nine patients developed gallstones post-operatively of whom five were in the VBG and four in the GBP group. CONCLUSIONS: weight loss following GBP was maintained, while VBG patients slowly regained.

Infection and sudden unexpected death in infancy: a systematic retrospective case review

BACKGROUND

The cause and mechanism of most cases of sudden unexpected death in infancy (SUDI) remain unknown, despite specialist autopsy examination. We reviewed autopsy results to determine whether infection was a cause of SUDI.

METHODS

We did a systematic retrospective case review of autopsies, done at one specialist centre between 1996 and 2005, of 546 infants (aged 7-365 days) who died suddenly and unexpectedly. Cases of SUDI were categorised as unexplained, explained with histological evidence of bacterial infection, or explained by non-infective causes. Microbial isolates gathered at autopsy were classified as non-pathogens, group 1 pathogens (organisms usually associated with an identifiable focus of infection), or group 2 pathogens (organisms known to cause septicaemia without an obvious focus of infection).

FINDINGS

Of 546 SUDI cases, 39 autopsies were excluded because of viral or pneumocystis infection or secondary bacterial infection after initial collapse and resuscitation. Bacteriological sampling was done in 470 (93%) of the remaining 507 autopsies. 2079 bacteriological samples were taken, of which 571 (27%) were sterile. Positive cultures yielded 2871 separate isolates, 484 (32%) of which showed pure growth and 1024 (68%) mixed growth. Significantly more isolates from infants whose deaths were explained by bacterial infection (78/322, 24%) and from those whose death was unexplained (440/2306, 19%) contained group 2 pathogens than did those from infants whose death was explained by a non-infective cause (27/243, 11%; difference 13.1%, 95% CI 6.9-19.2, p<0.0001 vs bacterial infection; and 8.0%, 3.2-11.8, p=0.001 vs unexplained). Significantly more cultures from infants whose deaths were unexplained contained Staphylococcus aureus (262/1628, 16%) or Escherichia coli (93/1628; 6%) than did those from infants whose deaths were of non-infective cause (S aureus: 19/211, 9%; difference 7.1%, 95% CI 2.2-10.8, p=0.005; E coli: 3/211, 1%, difference 4.3%, 1.5-5.9, p=0.003).

INTERPRETATION

Although many post-mortem bacteriological cultures in SUDI yield organisms, most seem to be unrelated to the cause of death. The high rate of detection of group 2 pathogens, particularly S aureus and E coli, in otherwise unexplained cases of SUDI suggests that these bacteria could be associated with this condition.

Effect of methylphenidate on attention in children with attention deficit hyperactivity disorder (ADHD): ERP evidence

Methylphenidate is the most common treatment for attention deficit hyperactivity disorder (ADHD) and has been shown to improve attention and behaviour. However, the precise nature of methylphenidate on specific aspects of attention at different dose levels remains unclear. We studied methylphenidate effects in ADHD from a neurophysiological perspective, recording event-related potentials (ERPs) during attention task performance in normal controls and children with ADHD under different dose conditions. Twenty children with ADHD and 20 age matched controls were assessed with a continuous performance task requiring subjects to identify repeating alphabetic characters. ERPs and behavioural measures were recorded and analyzed for trials where a correct response was made. The ADHD group was assessed off drug (baseline) and on placebo, low (0.28 mg/kg) and high (0.56 mg/kg) dose levels of methylphenidate. The results showed that the ADHD group at baseline was more impulsive and inattentive than controls and had shorter P2 and N2 latencies and longer P3 latencies. Low dose methylphenidate was associated with reduced impulsivity (fewer false alarms) and decreased P3 latencies, whereas the higher dose level was associated with reduced impulsivity and less inattention (more hits), as well as increased P2 and N2 latencies and decreased P3 latencies. Amplitudes were unaffected and there were no adverse effects of the higher dose for any of the children. These results suggest differential dosage effects and a dissociation between dose levels and aspects of processing.

The serotonin 5-HT1B receptor gene and attention deficit hyperactivity disorder

Recent research has suggested that serotonin, in addition to dopamine, may be involved in the development of attention deficit hyperactivity disorder (ADHD). Serotonin regulates dopaminergic neurotransmission in some areas of the brain via several 5-HT receptors including 5-HT1B. Animal studies have suggested the involvement of the 5-HT1B receptors in locomotor behaviour. For these reasons, we hypothesized that the 5-HT1B receptor gene may be a good candidate for genetic studies of ADHD. We tested for linkage disequilibrium between the 5-HT1B G861C polymorphism and ADHD in 115 families using the transmission disequilibrium test (TDT). We found evidence for a trend towards excess transmission of the 861G allele (chi(2) = 2.91, P = 0.09) that when further analysed for parental allele transmissions exhibited significantly greater paternal transmission of the G allele (chi(2) = 4.80, P = 0.03) to the affected child. Although preliminary, results from this study provide additional evidence that serotonin genes may be important risk factors for the development of ADHD.

Improved outcome for children with hepatoblastoma

Between 1981 and 1993, 41 children were treated for hepatoblastoma. Clinical, radiological and pathological data were reviewed retrospectively, focusing on surgical aspects of treatment and outcome. Fourteen children underwent primary resection of the hepatic tumour. One infant with severe congenital anomalies received only palliative treatment. Of 26 with irresectable disease, pulsed cytotoxic chemotherapy (cisplatin and doxorubicin) enabled subsequent surgical excision in 22 and one child with persistent extensive intrahepatic disease was successfully treated by liver transplantation. Thus, with a policy of selective preoperative chemotherapy, 90 per cent of hepatoblastomas were resectable. There were no perioperative deaths from haemorrhage but one child died from an intraoperative tumour embolus. A total of 28 survivors, 27 of whom are disease-free, were followed for a median of 5 years. The cumulative probability of survival in patients treated with intent to cure was 67 per cent. Analysis of survival data suggested a favourable outcome for those with a pure fetal histological tumour subtype. These results demonstrate significant progress in the treatment of hepatoblastoma.

Langerhans cell histiocytosis: the case for conservative treatment

Fifty eight children with Langerhans cell histiocytosis who were referred to this hospital between 1980 and 1987 were studied. Fourteen had single system disease, and 44 had multisystem disease, of whom 22 had vital organ dysfunction. A conservative approach to treatment was adopted, and when systemic treatment was indicated a short course of prednisolone was used first. Eight of the patients with single system disease required no treatment, while six received local treatment alone. Eight of the patients with multisystem disease did not require systemic treatment, 17 were given prednisolone alone, and 19 were given cytotoxic drugs. Of the 14 with single system disease 13 had no long term after effects. Eight of the patients with multisystem disease died, 24 had long term after effects, and 12 had none. Outcome was related to age and Lahey score. These results compare favourably with other series in which more aggressive approaches were used, and support our conservative approach to treatment.

Linkage study of catechol-O-methyltransferase and attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder is the most common child psychiatric disorder with a prevalence rate in an Ontario study of 9% in boys and 3% in girls [Szatmari et al., 1989]. This disorder is characterized by problems in the areas of attention, overactivity, impulse control, and distractibility. Strong evidence for a genetic component has been provided from twin, family, and adoption studies [for review see Levy et al., 1998] and molecular genetic studies are in progress by several groups worldwide. The Catechol-O-Methyltransferase (COMT) gene is an interesting candidate for ADHD as it is involved in the breakdown of dopamine and norepinephrine, neurotransmitters strongly implicated in the etiology of ADHD. In addition, children with velo-cardio-facial syndrome, a deletion syndrome of the chromosomal region 22q11 where the COMT gene has been localized, often have symptoms of ADHD suggesting this gene may have an etiological role in ADHD. In this study, we have tested for linkage in ADHD families using the functional polymorphism at codon 158 that determines COMT activity [Lachman et al., 1996] and analyzed the data with the transmission disequilibrium test (TDT). A total of 77 nuclear families collected from Toronto were genotyped. We find no evidence for linkage of this polymorphism and ADHD in our sample. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:710-713, 1999.

Evidence for the serotonin HTR2A receptor gene as a susceptibility factor in attention deficit hyperactivity disorder (ADHD)

A recent study demonstrated that treatment of hyperactive mice with psychostimulants and serotonergic agents produced a calming effect that was dependent on serotonergic neurotransmission and was not associated with any changes in extracellular dopamine levels. The complex interaction between the serotonergic and dopaminergic neurotransmitter systems suggests that a balance between the two systems may be necessary for mediating hyperactive behaviour. Defects in serotonin system genes, therefore, may disrupt normal brain serotonin function causing an imbalance between these neurotransmitter systems leading to the development of attention deficit hyperactivity disorder (ADHD). Using the transmission disequilibrium test (TDT), the current study assesses for linkage disequilibrium between polymorphisms in the serotonin HTR2A receptor gene and ADHD. One hundred and fifteen families with a total of 143 children diagnosed with ADHD (DSM-IV) were genotyped for the His452 Tyr and the T102C polymorphisms in the serotonin HTR2A receptor gene. TDT analysis revealed a preferential transmission of the 452Tyr allele to the affected offspring (P = 0.03), suggesting linkage disequilibrium of this polymorphism with ADHD. This may open a new door in ADHD molecular genetics research, expanding the existing view of a catecholaminergic hypothesis to include a serotonergic hypothesis and should help elucidate the complex interplay among the neurotransmitter systems in the etiology of ADHD.

Cost and outcome analysis of home parenteral and enteral nutrition

BACKGROUND

Previous estimates of the cost of home parenteral and enteral nutrition (HPEN) have excluded hospitalization costs or were conducted abroad and have limited applicability in the United States. Few studies have used validated measures to determine the effect of home nutrition support on quality of life.

METHOD

A cost and clinical outcome analysis was performed by retrospective review of charts of patients receiving HPEN from 1991 to 1996. Questionnaires to determine the influence of therapy on lifestyle (n = 41) and a general health status questionnaire, the short form 36-item survey (n = 39), were mailed to patients.

RESULTS

The annual cost per patient for parenteral solutions was $55,193 +/- 30,596 (mean +/- SD) based on Medicare charges and for enteral tube feedings was $9605 +/- 9327. The annual cost of hospitalization ranged from zero to $140,220 in the parenteral nutrition group and from zero to $39,204 in the enteral nutrition group. The annual number of hospitalizations per patient for patients receiving parenteral nutrition ranged from 0.52 to 1.10, compared with 0 to 0.50 in the enteral nutrition population. The health status of HPEN patients was significantly lower (p < .05) in five of the eight short-form 36 health domains compared with the general population. The areas of lifestyle most frequently affected were travel, sleep, exercise and leisure.

CONCLUSIONS

The majority of the cost of therapy was associated with the direct provision of nutrition, although in some patients the hospitalization expenditure exceeded this cost. Home nutrition support had a significant negative impact on a patient's quality of life and lifestyle.

Further evidence from haplotype analysis for linkage of the dopamine D4 receptor gene and attention-deficit hyperactivity disorder

Several studies have suggested a possible association of a polymorphism at the dopamine D4 receptor gene and attention-deficit hyperactivity disorder [LaHoste et al., 1996; Rowe et al., 1998; Smalley et al., 1998; Sunohara et al., submitted; Swanson et al., 1998]. The allele reported to be associated with attention-deficit hyperactivity disorder (ADHD) is the allele with seven copies of the 48 bp repeat in the third exon. We extend our study of the dopamine D4 gene and ADHD by testing for linkage using two additional polymorphisms in the dopamine D4 receptor gene and a polymorphism in the closely linked gene, tyrosine hydroxylase. We also searched for two previously reported deletions, a 13 bp and a 21 bp deletion in the first exon. We examined the haplotypes of three polymorphisms of the D4 receptor gene and observed biased transmission of two of these haplotypes. Our findings further support the role of the dopamine D4 gene in ADHD.

Next Generation DNA Sequencing of Tissues from Infected Diabetic Foot Ulcers

We used next generation DNA sequencing to profile the microbiome of infected Diabetic Foot Ulcers (DFUs). The microbiota was correlated to clinical parameters and treatment outcomes to determine if directed antimicrobial therapy based on conventional microbiological cultures are relevant based on genomic analysis. Patients≥18years presenting with a new Diabetic Foot Infection (DFI) who had not received topical or oral antimicrobials in the two weeks prior to presentation, were eligible for enrolment. Tissue punch biopsies were obtained from infected DFUs for analysis. Demographics, clinical and laboratory data were collected and correlated against microbiota data. Thirty-nine patients with infected DFUs were recruited over twelve-months. Shorter duration DFUs (<six weeks) all had one dominant bacterial species (n=5 of 5, 100%, p<0.001), Staphylococcus aureus in three cases and Streptococcus agalactiae in two. Longer duration DFUs (≥six weeks) were diversely polymicrobial (p<0.01) with an average of 63 (range 19-125) bacterial species. Severe DFIs had complex microbiomes and were distinctly dissimilar to less severe infections (p=0.02), characterised by the presence of low frequency microorganisms. Nineteen patients (49%) during the study period experienced antimicrobial treatment failure, but no overall differences existed in the microbiome of patients who failed therapy and those who experienced treatment success (p=0.2). Our results confirm that short DFUs have a simpler microbiome consisting of pyogenic cocci but chronic DFUs have a highly polymicrobial microbiome. The duration of a DFU may be useful as a guide to directing antimicrobial therapy.

Liver failure associated with mitochondrial DNA depletion

BACKGROUND/AIMS

Liver failure in infancy can result from several disorders of the mitochondrial respiratory chain. In some patients, levels of mitochondrial DNA are markedly reduced, a phenomenon referred to as mitochondrial DNA depletion. To facilitate diagnosis of this condition, we have reviewed the clinical and pathological features in five patients with mitochondrial DNA depletion.

METHODS

Cases were identified by preparing Southern blots of DNA from muscle and liver, hybridising with appropriate probes and quantifying mitochondrial DNA relative to nuclear DNA.

RESULTS

All our patients with mitochondrial DNA depletion died of liver failure. Other problems included hypotonia, hypoglycaemia, neurological abnormalities (including Leigh syndrome) and cataracts. Liver histology showed geographic areas of fatty change, bile duct proliferation, collapse of liver architecture and fibrosis; some cells showed decreased cytochrome oxidase activity. Muscle from three patients showed mitochondrial proliferation, with loss of cytochrome oxidase activity in some fibres but not in others; in these cases, muscle mitochondrial DNA levels were less than 5% of the median control value. The remaining two patients (from a single pedigree) had normal muscle histology and histochemistry associated with less severe depletion of mitochondrial DNA in muscle.

CONCLUSIONS

Liver failure is common in patients with mitochondrial DNA depletion. Associated clinical features often include neuromuscular disease. Liver and muscle histology can be helpful in making the diagnosis. Mitochondrial DNA levels should be measured whenever liver failure is thought to have resulted from respiratory chain disease.

Clinicopathological features of paediatric deaths due to myocarditis: an autopsy series

INTRODUCTION

Myocarditis is a recognised cause of cardiac failure in childhood but the frequency of myocarditis as a cause of sudden unexpected death across the paediatric age range is uncertain.

METHODS

A structured review of the results of all autopsies carried out in a single paediatric centre over a 10-year period, including the results of all investigations performed as part of the centre's policy for the post-mortem investigation of paediatric deaths.

RESULTS

During the study period there were 1516 autopsies of children aged 0-18 years. Histologically proven myocarditis was present in 28 cases (1.8%, age range 10 days to 16 years, median age 10 months), of which 16 (57%) presented as sudden death. More than half of all cases (54%) occurred in infants less than 1 year of age, accounting for 2% of infant deaths referred for autopsy, compared with around 5% of childhood deaths over the age of 5 years. In almost 40% of cases there were no macroscopic cardiac abnormalities, the diagnosis being entirely dependent on routine histological examination of the heart, and post-mortem heart weight was normal in the majority of cases. Virus was detected in nine (36%) of the 25 cases in whom virological analyses were performed. The histological features were similar in all cases, with an interstitial inflammatory cell infiltrate, predominantly lymphocytic, with focal myocyte necrosis and interstitial oedema.

CONCLUSIONS

Myocarditis is a rare cause of death in infancy and childhood, and the majority of cases present as sudden unexpected deaths, which require routine histological sampling of the heart for its detection.

The histiocytoses of childhood

The histiocytoses of childhood include Langerhans' cell histiocytosis, haemophagocytic syndrome (familial and reactive), sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease), juvenile xanthogranuloma and malignant histiocytosis. These disorders show wide variation in their clinical presentation, prognosis and genetic implications. All are characterized by localized or generalized proliferation of histiocytes, but they differ in their morphology, histochemical and immunochemical staining patterns and electronmicroscopical features. On the basis of a comprehensive clinical history and critical interpretation of morphology and immunocytochemistry using an appropriately selected panel of antibodies, a diagnosis can be reached in the majority of cases.

The SNAP25 gene as a susceptibility gene contributing to attention-deficit hyperactivity disorder

The synaptosomal-associated protein of 25 kDa gene (SNAP25) has been suggested as a genetic susceptibility factor in attention-deficit hyperactivity disorder (ADHD) based on the mouse strain coloboma. This strain is hemizygous for the SNAP25 gene and displays hyperactivity that responds to dextroamphetamine, but not to methylphenidate. Previously, we reported association of SNAP25 and ADHD using two polymorphisms. To further investigate this gene, we screened the exons for DNA variation and genotyped ten additional polymorphisms in an expanded sample of families from Toronto and a second sample of families collected in Irvine, CA. Significant results were observed in the Toronto sample for four markers, although not in the Irvine sample. The paper discusses the possible influence of the selection criteria on these differential results. The Irvine sample selected subjects that met the DSM-IV combined subtype diagnosis, whereas the Toronto sample included all subtypes. Analysis of the DSM-IV subtypes in the Toronto sample indicated that the differential results were not attributable to ADHD subtype. Differences in ethnicity, differential medication response, and other clinical characteristics of the samples cannot be ruled out at this time. Quantitative analysis of the dimensions of hyperactivity/impulsivity and inattention in the Toronto sample found that both behavioral traits were associated with SNAP25. Our findings continue to support SNAP25 in the susceptibility to ADHD.

Linkage of the dopamine receptor D1 gene to attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) has a strong genetic basis, and evidence from human and animal studies suggests the dopamine receptor D1 gene, DRD1, to be a good candidate for involvement. Here, we tested for linkage of DRD1 to ADHD by examining the inheritance of four biallelic DRD1 polymorphisms [D1P.5 (-1251HaeIII), D1P.6 (-800HaeIII), D1.1 (-48DdeI) and D1.7 (+1403Bsp1286I)] in a sample of 156 ADHD families. Owing to linkage disequilibrium between alleles at the four markers, only three haplotypes are common in our sample. Using the transmission/disequilibrium test (TDT), we observed a strong bias for transmission of Haplotype 3 (1.1.1.2) from heterozygous parents to their affected children (P=0.008). Furthermore, using quantitative trait TDT analyses, we found significant and positive relationships between Haplotype 3 transmission and the inattentive symptoms, but not the hyperactive/impulsive symptoms, of ADHD. These findings support the proposed involvement of DRD1 in ADHD, and implicate Haplotype 3, in particular, as containing a potential risk factor for the inattentive symptom dimension of the disorder. Since none of the four marker alleles comprising Haplotype 3 is predicted to alter DRD1 function, we hypothesize that a functional DRD1 variant, conferring susceptibility to ADHD, is on this haplotype. To search for such a variant we screened the DRD1 coding region, by sequencing, focusing on the children who showed preferential transmission of Haplotype 3. DNA from 41 children was analysed, and no sequence variations were identified, indicating that the putative DRD1 risk variant for ADHD resides outside of the coding region of the gene.

Pulmonary involvement by Niemann-Pick disease. A report of six cases

AIMS

Although pulmonary involvement is a known cause of morbidity in Niemann-Pick disease, histological features in the lung are not well characterized. The purpose of this study is to document the histological features seen in pulmonary involvement by types B and C Niemann-Pick disease and to correlate them with clinical and imaging data.

METHODS AND RESULTS

Surgical lung biopsies from six patients (four with type B and two with type C disease) were reviewed and all showed diffuse endogenous lipid pneumonia, with lesser involvement of the interstitium by fibrosis and foamy macrophage accumulation. In type B disease only, there was also fine cytoplasmic vacuolation within the cytoplasm of ciliated epithelial cells. Neither disease showed foamy changes within pneumocytes. One patient had a bronchial cast removed on whole lung lavage. Electron microscopy showed abnormal lamellar inclusions within lysosomes of affected cells in type B disease. In patients with type C disease, biopsies were undertaken as part of investigations into acute respiratory failure in the context of multiorgan systemic presentation. Three patients with type B disease had clinical disease limited to the lung, all adults (mean age of 40 years) with unexplained diffuse parenchymal lung disease and mainly ground-glass shadowing on high-resolution computed tomography.

CONCLUSIONS

Niemann-Pick disease should be considered for any patient with unexplained diffuse endogenous lipid pneumonia, even when disease is limited to the lungs and presentation is during adulthood.

Molecular and particulate depositions for regional myocardial flows in sheep

The deposition of microspheres in small tissue regions is not strictly flow dependent. In comparison with the soluble flow marker 2-iododesmethylimipramine (IDMI), deposition of 16.5-microns microspheres was mildly but systematically biased into high flow regions of rabbit hearts (Bassingthwaighte JB, Malone MA, Moffett T-C, King RB, Little SE, Link JM, Krohn KA. Am J Physiol 1987;253 (Heart Circ Physiol 22):H184-H193). To examine the possibility of bias in larger hearts, a similar study was undertaken in sheep. 141Ce- and 103Ru-labeled 16.5-microns microspheres in one syringe and 125I- and 131I-DMI in another syringe were injected simultaneously into the left atrium of five open-chest sheep while obtaining reference blood samples from the femoral artery. In six other sheep, one microsphere type and one IDMI were used. Hearts were removed 1 minute after injection, cut into approximately 254 pieces averaging 217 mg, and regional deposition densities calculated for each tracer from the isotopic counts. Correlations in the five animals between the two differently labeled IDMIs and between the two microspheres were both greater than or equal to 0.98. In all 11 sheep, scatter plots of microsphere deposition densities versus IDMI densities showed that differences between microspheres and IDMI had substantially more scatter (0.84 less than r less than 0.98) but were not random. Microsphere depositions tended to be lower than IDMI depositions in low flow regions and higher in high flow regions, in accord with the expected bias that at a bifurcation a microsphere is most likely to enter the branch with higher flow. There was less bias ascribable to endomyocardial/epicardial maldistribution. Thus, while microsphere depositions appear to err systematically with respect to flow when the regions of interest are small enough that the diameters of their arterioles are only a few times those of the microspheres, microspheres are, in sheep as in rabbits, adequate for estimating regional flows.