Thymic re-entry of mature activated T cells and increased negative selection in vascularized allograft recipients

Transplantation tolerance is a dynamic state that involves several homeostatic mechanisms intrinsic to the host. One of these mechanisms is activation-induced T cell death (AICD). However, it is unclear where AICD takes place during alloreactive responses. Since activated T cells can re-enter the thymus, we hypothesized that mature T cells activated by an allograft could be deleted upon re-entry into the thymus. To test this hypothesis, we used wild-type or 2C TCR transgenic mice receiving syngeneic or allogeneic heterotopic, vascularized heart grafts. First, we demonstrated that ex vivo CFSE-labelled T cells re-entered the thymus when transferred into allograft recipients but not when transferred into isograft recipients. Next, we compared the changes in cell subset numbers and incidence of apoptosis in the thymi and spleens of allograft or isograft recipients. Seven days after transplantation, at a time in which all the allografts were undergoing rejection, cells expressing donor-MHC class II molecules had migrated to the thymus and to the spleen. In the thymus of allograft recipients, overall cellularity was significantly reduced by 40% and associated with an increase in the number of double negative (CD4-CD8-) thymocytes and a decrease in double positive (CD4+CD8+) thymocytes, consistent with increased negative selection of thymocytes. Additionally, thymi of allograft recipients showed an increase in the number of recently activated, mature T cells (TCRhi, CD25+, CD44+) and a significant increase in the number of apoptotic cells, especially in the thymic medulla, that involved mature T cells as indicated by the TCRhi, CD44+, CD4 or CD8 single positive phenotype. Spleens of allograft recipients were increased in size and cellularity but did not show any of the changes in cell subsets seen in the thymi. Our data show that after allografting there is an increase in apoptotic cell death that is associated with negative selection of developing thymocytes as well as of alloreactive mature T cells that have re-entered the thymus upon activation in the periphery. This may occur upon migration of graft-derived antigen-presenting cells to the thymus.

Hyperhexosemia induced functional and structural changes in the kidneys: role of endothelins

BACKGROUND/AIMS

Glomerular basement membrane (GBM) thickening and mesangial matrix expansion are characteristic features of diabetic nephropathy. The present study investigates the role of endothelins (ETs) in the pathogenesis of such changes in diabetic nephropathy.

METHODS

Diabetic (streptozotocin-induced, 65 mg/kg), galactose-fed (30%) and control animals were followed up for 1 and 6 months. Animal groups also included diabetic and galactose fed animals on dual ET(A)/ET(B) receptor antagonist bosentan (100 mg/kg). A semi-quantitative reverse transcription polymerase chain reaction method was used to quantify mRNA expression of ET-1, ET-3, ET(A), ET(B), fibronectin and collagen alpha2(IV). Histological analyses of the kidneys and ET-1, ET-3 and fibronectin immunohistochemistry were performed. Morphometric assessment of the GBM after 6 months was performed.

RESULTS

Diabetes increased mRNA expression of ET-1, ET-3, ET(A), ET(B), fibronectin and collagen alpha2(IV) after one and six months. In contrast, although increased ET(A) and ET(B) mRNAs were present following galactose feeding both at 1 and 6 months, ET-1, ET-3, fibronectin and collagen alpha2(IV)mRNAs were increased after 6 months. Both diabetes and galactose feeding caused increased GBM thickening. Furthermore, diabetes caused an increase in mesangial matrix production. Bosentan prevented increased fibronectin and collagen alpha2(IV) mRNA expression, increased mesangial matrix deposition and GBM thickening.

CONCLUSION

This study has demonstrated that diabetes and galactose feeding induced functional and structural changes in the kidney are mediated via ETs.

Vocal cord dysfunction presenting as refractory asthma

Vocal cord dysfunction is a rare variety of upper airway obstruction characterized by typical laryngoscopic features and may mimic an acute asthma attack. The case presented in this report pertains to a 15-year-old girl who had repeated acute episodes of dyspnoea and wheezing and remained non-responsive to corticosteroids and inhaled bronchodilators requiring endotracheal intubations for adequate control. Laryngoscopic findings were consistent with vocal cord dysfunction. She was treated with a tracheostomy and psychological support.

Cidofovir as primary pre-emptive therapy for post-transplant cytomegalovirus infections

Pre-emptive antiviral therapy for CMV infection following allogeneic stem cell transplantation is an effective strategy for preventing CMV disease. This entails the logistic difficulty of daily intravenous therapy with ganciclovir or foscarnet to clinically asymptomatic patients. Cidofovir (CDV) is effective against CMV in vitro and has the practical advantage of weekly administration. However, there are limited data on the pre-emptive use of CDV in CMV infections. We carried out a pilot study exploring the efficacy and toxicity of CDV as primary pre-emptive therapy for CMV infections monitored by PCR-based assays. CDV was used at 5 mg/kg with probenecid and hydration, weekly for a maximum of 4 weeks, followed by fortnightly maintenance treatment. Four patients were treated with CDV and two of them responded. Both the non-responders developed CMV disease. There was no renal toxicity noted in any of the patients, but three patients had severe vomiting and one developed uveitis, which precluded maintenance treatment in the two responders. Following failure of CDV, foscarnet was effective in controlling the CMV infection in both patients, although the infection recurred in both. Thus, larger randomised studies are required before CDV can be recommended as a primary pre-emptive therapy for post-transplant CMV infections.

The usefulness of prostate specific antigen density as a screening method for prostatic carcinoma

Prostate specific antigen (PSA) has been used extensively for monitoring the progression of prostatic cancer since its discovery in 1979. Unfortunately the measurement of PSA in serum is not sufficiently specific for early detection of prostatic carcinoma (CaP) as it is secreted by normal as well as hyperplastic or cancerous prostatic tissue. As serum PSA is the reflection of the number of prostatic epithelial cells, a small cancerous prostate gland having increased number of cells per unit volume leaks more PSA in serum than a benign, large gland. Thus the concept of PSA density (PSAD) has been proposed (the quotient of serum PSA divided by the volume of prostate in cubic centimeter) as an indicator for prostatic malignancy. In the present study pre-operative PSAD values of 65 cases of prostatic diseases were calculated [54 cases of benign prostatic hyperplasia (BPH) and 11 cases of C3P]. Serum PSA was measured by enzyme linked immunosorbent assay (ELISA) method and the prostatic volume was measured by transrectal ultrasonography (TRUS). Although 8 cases of BPH (14.8%) had raised PSA level, abnormal PSAD (0.1 or above) was noted in only 3 cases. All cases having PSAD value above 0.2 had carcinoma. The PSAD value above 0.1 in cases of CaP was found to be significant (p<0.001). By using PSAD as screening test the sensitivity increased from 85.1% to 94.4% and positive predictive value increased from 55.5% to 75%, compared to the detection of carcinoma by measuring PSA alone. The present study concludes that PSAD is more useful for prediction of CaP and the need of prostatic biopsy for early detection.

The psychosocial assessment of deliberate self harm: using clinical audit to improve the quality of the service

OBJECTIVES

To determine whether simple service initiatives resulted in an improvement in the quality of the psychosocial assessment of adults presenting with deliberate self harm (DSH) by accident and emergency (A&E) medical staff.

METHOD

The quality of psychosocial assessment of adults presenting to an A&E department after DSH for a 12 month period was examined using an audit instrument developed from the Royal College of Psychiatrists' standards of service provision for the general hospital management of adult DSH. The results were then compared with a similar audit that had been conducted three years previously. A number of service improvements had been implemented after this first audit.

RESULTS

A total of 1359 episodes of adult DSH were identified. When compared with the previous audit, the frequency of information recorded in the case notes was significantly improved in all areas of the psychosocial assessment (p < 0.001) apart from mental state. There were significant changes in treatment between the two audits, with a higher proportion in 1997/8 (362, 26.5%) assessed by a mental health specialist in the department than in 1994/5 (154, 16.5%; chi(2) = 33, p < 0.001). The frequency of recorded information for those who were not admitted directly to medical or surgical wards was significantly higher for all factors (p<0.01) apart from conscious level and medical history.

CONCLUSIONS

A substantial improvement in the quality of the psychosocial assessment of adults presenting with DSH by A&E medical staff was achieved with the introduction of simple service developments. Encouraging staff to use a comprehensive checklist, proved particularly beneficial.

Respiratory virus infections in adult T cell-depleted transplant recipients: the role of cellular immunity

BACKGROUND

Little is known about the role of cellular immunity in respiratory virus infections after bone marrow transplantation.

METHODS

Forty allograft recipients T-cell depleted with Campath antibodies were evaluated for respiratory virus infections in an active surveillance program with early initiation of antiviral therapy.

RESULTS

Eighteen episodes of respiratory virus infection were detected in nine patients (22%) at a median of 95 days, with lower respiratory involvement in 44%. Fourteen episodes were treated with antiviral therapy for 7 to 46 days, with 11% mortality. Respiratory virus infections were more common in patients receiving Campath 100 mg in vivo, but delayed CD4+ recovery was the most significant risk factor.

CONCLUSIONS

Respiratory virus infections are common and often recurrent in patients with severe CD4+ T lymphopenia. However, the mortality was low, which may have been due to early institution of antiviral treatment or reduced inflammatory damage to the lungs due to severe lymphopenia.

No evidence for a new variant of measles-mumps-rubella-induced autism

OBJECTIVE

A link has been postulated between measles-mumps-rubella (MMR) vaccine and a form of autism that is a combination of developmental regression and gastrointestinal symptoms that occur shortly after immunization. This hypothesis has involved 3 separate claims: 1) that there is new phenotype of autism involving regression and gastrointestinal symptoms, 2) that this new variant is responsible for the alleged rise of autism rates, and 3) that this phenotype is associated with biological findings suggestive of the persistence of measles infection. We tested the first of these claims. If this new "autistic enterocolitis" syndrome had some validity, then 1 or several of the following 6 predictions should be supported by empirical data: 1) childhood disintegrative disorder has become more frequent, 2) the mean age of first parental concern for autistic children who are exposed to MMR is closer to the mean immunization age than in children who are not exposed to MMR, 3) regression in the development of children with autism has become more common in MMR-vaccinated children, 4) the age of onset for autistic children with regression clusters around the MMR immunization date and is different from that of autistic children without regression, 5) children with regressive autism have distinct symptom and severity profiles, and 6) regressive autism is associated with gastrointestinal symptoms and/or inflammatory bowel disorder.

METHODS

Three samples were used. Epidemiologic data on 96 children (95 immunized with MMR at a median age of 13.5 months) who were born between 1992 and 1995 and had a pervasive developmental disorder diagnosis as reported in a recent UK survey (post-MMR sample) were compared with data from 2 previous clinical samples (1 pre-MMR [n = 98] and 1 post-MMR [n = 68]) of autistic patients. All patients were assessed with the standardized Autism Diagnostic Interview (ADI), allowing rigorous comparison of age at first parental concerns and rates of regression across samples. Reliability was excellent on ADI scores, age of parental concern, and developmental regression. Furthermore, data on bowel symptoms and disorders were available in the epidemiologic survey from both pediatric and parental sources, and immunization dates were obtained from computerized records.

RESULTS

The prevalence of childhood disintegrative disorder was 0.6/10 000 (95% confidence interval: 0.02-3.6/10 000); this very low rate is consistent with previous estimates and is not suggestive of an increased frequency of this form of pervasive developmental disorder in samples of children who are immunized with MMR. There was no difference in the mean age at first parental concern between the 2 samples exposed to MMR (19.3 and 19.2 months) and the pre-MMR sample (19.5 months). Thus, MMR immunization was not associated with a shift toward an earlier age for first parental concerns. Similarly, the rate of developmental regression reported in the post-MMR sample (15.6%) was not different from that in the pre-MMR sample (18.4%); therefore, there was no suggestion that regression in the developmental course of autism had increased in frequency since MMR was introduced. In the epidemiologic sample, the subset of autistic children with regression had no other developmental or clinical characteristics, which would have argued for a specific, etiologically distinct phenotype. Parents of autistic children with developmental regression detected the first symptoms at a very similar age (19.8 months) to those of autistic children without regression (19.3 months). Moreover, the mean intervals from MMR immunization to parental recognition of autistic symptoms were comparable in autistic children with or without regression (248 vs 272 days; not significant). In the epidemiologic sample, gastrointestinal symptoms were reported in 18.8% of children. Constipation was the most common symptom (9.4%), and no inflammatory bowel disorder was reported. Furthermore, there was no association between developmental regression and gastrointestinal symptoms (odds ratio: 0.63; 95% confidence interval: 0.06-3.2; not significant), and only 2.1% of the sample experienced both problems, a rate that did not exceed chance expectations.

CONCLUSIONS

No evidence was found to support a distinct syndrome of MMR-induced autism or of "autistic enterocolitis." These results add to the recent accumulation of large-scale epidemiologic studies that all failed to support an association between MMR and autism at population level. When combined, the current findings do not argue for changes in current immunization programs and recommendations.

Lipid peroxidation associated protein damage in rat brain crude synaptosomal fraction mediated by iron and ascorbate

In crude synaptosomal fractions from rat brain exposed to iron and ascorbate, enhanced lipid peroxidation (more than 3-fold compared to control), loss of protein thiols up to the extent of 40% compared to control, increased incorporation of carbonyl groups into proteins (more than 4.5-fold compared to control) and non-disulphide covalent cross-linking of membrane proteins have been observed. The phenomena are not inhibited by catalase or hydroxyl radical scavengers like mannitol or dimethyl sulphoxide. However, chain breaking antioxidants like alpha-tocopherol and butylated hydroxytoluene prevent both lipid peroxidation and accompanying protein oxidation. It is suggested that in this system lipid peroxidation propagated by the decomposition of preformed lipid hydroperoxides by iron and ascorbate is the primary event and products of the peroxidation process cause secondary protein damage. In view of high ascorbate content of brain and availability of several transition metals, such ascorbate mediated oxidative damage may be relevant in the aetiopathogenesis of several neurodegenerative disorders as well as ageing of brain.

Pre-emptive oral ribavirin therapy of paramyxovirus infections after haematopoietic stem cell transplantation: a pilot study

Infections with the paramyxoviruses, respiratory syncytial virus (RSV) and parainfluenza virus (PIV) can result in serious morbidity and mortality after haemopoietic stem cell transplant (HSCT). Once pneumonia develops, the outcome of these infections is often poor despite anti-viral therapy. Aerosolised ribavirin has been evaluated as pre-emptive therapy for post-transplant RSV infections with some success. Due to the financial and logistic burden involved with the use of aerosolised ribavirin, we explored the efficacy and toxicity of oral ribavirin for pre-emptive therapy of post-transplant RSV and PIV infections in a dose escalating schedule (15-60 mg/kg/day). Five episodes each of RSV and PIV were treated in seven patients. Five patients were receiving treatment for GVHD and two acquired the infection in the pre-engraftment period. All the episodes of RSV infection improved with oral ribavirin with dose escalation to 30-45 mg/kg in three of them. On the other hand, only two of the five PIV infections improved with oral ribavirin. Of the three non-responders, two infections were acquired in the pre-engraftment period with one death from PIV pneumonia. Reversible anaemia was the only side-effect noted in patients treated for over 2 weeks. Thus, the use of oral ribavirin was well tolerated in the post-transplant period with no untoward toxicities. There was a trend towards better response in RSV infections, which needs to be further explored in controlled studies.

Mapping and monitoring the health and vitality of coral reefs from satellite: a biospheric approach

Biospheric studies of coral reefs require a planetary perspective that only remote sensing from space can provide. This article reviews aspects of monitoring and mapping coral reefs using Landsat and Spot satellite images. It details design considerations for developing a sensor for equatorial orbiting spacecraft, including spectral characteristics of living corals and the spatial resolution required to map coral reef communities. Possible instrumentation choices include computer techniques, filtered imagers, push-broom spectral imagery, and a newly developed hyperspectral imaging scheme using tomographic reconstruction. We compare the salient features of each technique and describe concepts for a payload to conduct planetary-scale coral reef monitoring.

High-glucose-induced metallothionein expression in endothelial cells: an endothelin-mediated mechanism

Vascular endothelial cells are constantly exposed to oxidative stress and must be protected by physiological responses. In diabetes mellitus, endothelial cell permeability is impaired and may be increased by high extracellular glucose concentrations. It has been postulated that metallothionein (MT) can protect endothelial cells from oxidative stress with its increased expression by cytokines, thrombin, and endothelin (ET)-1. In this study, we demonstrate that high glucose concentration can induce MT expression in endothelial cells through a distinct ET-dependent pathway. Exposure of human umbilical vein endothelial cells (HUVEC) to increasing concentrations of glucose resulted in a rapid dose-dependent increase in MT-2 and ET-1 mRNA expression. MT expression may be further augmented with addition of ET-1. Preincubation of the cells with the specific ET(B) antagonist BQ-788 blocked MT-2 mRNA expression more effectively than the ET(A) inhibitor TBC-11251. High glucose also increased immunoreactive MT protein expression and induced translocation of MT into the perinuclear area. Perinuclear localization of MT was related to high-glucose-induced reorganization of F-actin filaments. These results demonstrate that an increase in extracellular glucose in HUVEC can lead to a rapid dose-dependent increase in MT-2 mRNA expression and to perinuclear localization of MT protein with changes to the cytoskeleton. These effects are mediated via the ET receptor-dependent pathway.

Thyroid hormones in treatment of mood disorders

Although lithium carbonate is still the best validated and most preferred drug used for augmenting treatment of depression, T3 is perhaps the next best agent in this regard. Equivocal evidence, clinical skepticism and lack of data with SSRIs have prevented its widespread use. On the basis of whatever evidence is available it appears to be safe and effective. T4 is useful for replacement purpose and in high doses may have a role in augmenting mood stabilizers. Evidence for other therapeutic effects of thyroid hormones seems to be gathering, but they cannot be recommended yet in other situations as a part of routine clinical practice. Further research about the various therapeutic aspects of thyroid hormones is still required, since this is an area that seems to hold much promise.

Culture and schizophrenia and other psychotic disorders

The comparative study of schizophrenia and related disorders across cultures has come a long way since Kraepelin advocated its cause, following his trip to Java at the beginning of the last century. The principal development since then has been the burgeoning of interest in the field, culminating in innovative and ambitious international collaborative research by the WHO. Despite reservations about covert ideology or about the more overt methodologic difficulties, the balance of evidence from these and similar studies suggests that: It is feasible to conduct such research despite the numerous hazards. There is a certain uniformity to the way schizophrenia presents globally; there are equally significant cultural differences. The outcome of schizophrenia appears to be better in developing, than developed cultures; reasons for this are far from clear, nevertheless, it can be safely assumed that culturally-determined processes, whether social or environmental, are partly responsible. Overall, the study of schizophrenia in different cultures has proved useful in establishing the pancultural and the culture-specific properties of this and related disorders.

Attenuation of compensatory right ventricular hypertrophy and heart failure following monocrotaline-induced pulmonary vascular injury by the Na+-H+ exchange inhibitor cariporide

Pulmonary hypertension results in compensatory right ventricular (RV) hypertrophy. We studied the role of the Na+-H+ exchange (NHE) in the latter process by determining the effect of the NHE-1 inhibitor cariporide after monocrotaline-induced pulmonary artery injury. Sprague-Dawley rats received a control or cariporide diet for 7 days, at which time they were administered either monocrotaline (60 mg/kg) or its vehicle. Twenty-one days later, monocrotaline control, but not cariporide-fed animals, demonstrated increased RV weights and cell size of 65 and 52%, respectively. Monocrotaline alone significantly increased RV systolic pressure and end diastolic pressure by 70 and 94%, respectively, whereas corresponding values with cariporide were significantly reduced to 33 and 42%. Central venous pressure increased by 414% in control animals, which was significantly reduced by cariporide. Monocrotaline treatment produced a decrease in cardiac output of 28 and 8% in the absence or presence of cariporide (P < 0.05 between groups), respectively. Although body weights were significantly lower in both monocrotaline-treated groups compared with vehicle treatment, with cariporide the net gain in body weight was twice that seen in the monocrotaline-treated animals without cariporide. Monocrotaline also increased RV NHE-1 and atrial natriuretic peptide mRNA expression, which was abrogated by cariporide. Monocrotaline-induced myocardial necrosis, fibrosis, and mononuclear infiltration was completely prevented by cariporide. Cariporide had no effect on monocrotaline-induced pulmonary intimal wall thickening. Our results demonstrate that cariporide directly attenuates myocardial dysfunction after monocrotaline administration independent of pulmonary vascular effects. NHE-1 inhibition may represent an effective adjunctive therapy that selectively targets myocardial hypertrophic responses in pulmonary vascular injury.

Will mixed chimerism cure autoimmune diseases after a nonmyeloablative stem cell transplant?

BACKGROUND

Mixed chimerism after allogeneic bone marrow transplantation has been shown to cure a number of genetic disorders in both the clinical and experimental settings. Although encouraging results have been reported from animal experiments, the role of mixed chimerism in eliminating autoimmune disorders is not clear.

METHODS

A 50-year-old man with extensive psoriasis received an allogeneic transplant from his brother after nonmyeloablative conditioning with fludarabine, melphalan, and Campath-1H for relapsed non-Hodgkin's lymphoma. The chimerism status and the immunological recovery after the transplant were serially monitored.

RESULTS

Twenty-one months after the transplant, the patient continues to be in complete remission from psoriasis and lymphoma with stable mixed chimerism (30% to 40% donor cells), despite significant recovery of T-cell subsets and antigen-specific response.

CONCLUSIONS

If mixed chimerism can be achieved safely with novel low-intensity conditioning regimens and results in sustained remission of autoimmune diseases, allogeneic transplantation may become a realistic therapy in the management of some patients with autoimmune disease.

Differential interactions of antitumor antibiotics chromomycin A(3) and mithramycin with d(TATGCATA)(2) in presence of Mg(2+)

The antitumor antibiotics chromomycin A(3) (CHR) and mithramycin (MTR) are known to inhibit macromolecular biosynthesis by reversibly binding to double stranded DNA with a GC base specificity via the minor groove in the presence of a divalent cation such as Mg(2+). Earlier reports from our laboratory showed that the antibiotics form two types of complexes with Mg(2+): complex I with 1:1 stoichiometry and complex II with 2:1 stoichiometry in terms of the antibiotic and Mg(2+). The binding potential of an octanucleotide, d(TATGCATA)(2), which contains one potential site of association with the above complexes of the two antibiotics, was examined using spectroscopic techniques such as absorption, fluorescence, and circular dichroism. We also evaluated thermodynamic parameters for the interaction. In spite of the presence of two structural moieties of the antibiotic in complex II, a major characteristic feature was the association of a single ligand molecule per molecule of octameric duplex in all cases. This indicated that the modes of association for the two types of complexes with the oligomeric DNA were different. The association was dependent on the nature of the antibiotics. Spectroscopic characterization along with analysis of binding and thermodynamic parameters showed that differences in the mode of recognition by complexes I and II of the antibiotics with polymeric DNA existed at the oligomeric level. Analysis of the thermodynamic parameters led us to propose a partial accommodation of the ligand in the groove without the displacement of bound water molecules and supported earlier results on the DNA structural transition from B --> A type geometry as an obligatory requirement for the accommodation of the bulkier complex II of the two drugs. The role of the carbohydrate moieties of the antibiotics in the DNA recognition process was indicated when we compared the DNA binding properties with the same type of Mg(2+) complex for the two antibiotics.

Reproducible and inexpensive probe preparation for oligonucleotide arrays

We present a new protocol for the preparation of nucleic acids for microarray hybridization. DNA is fragmented quantitatively and reproducibly by using a hydroxyl radical-based reaction, which is initiated by hydrogen peroxide, iron(II)-EDTA and ascorbic acid. Following fragmentation, the nucleic acid fragments are densely biotinylated using a biotinylated psoralen analog plus UVA light and hybridized on microarrays. This non-enzymatic protocol circumvents several practical difficulties associated with DNA preparation for microarrays: the lack of reproducible fragmentation patterns associated with enzymatic methods; the large amount of labeled nucleic acids required by some array designs, which is often combined with a limited amount of starting material; and the high cost associated with currently used biotinylation methods. The method is applicable to any form of nucleic acid, but is particularly useful when applying double-stranded DNA on oligonucleotide arrays. Validation of this protocol is demonstrated by hybridizing PCR products with oligonucleotide-coated microspheres and PCR amplified cDNA with Affymetrix Cancer GeneChip microarrays.

Pervasive developmental disorders in preschool children

CONTEXT

Prevalence rates of autism-spectrum disorders are uncertain, and speculation that their incidence is increasing continues to cause concern.

OBJECTIVE

To estimate the prevalence of pervasive developmental disorders (PDDs) in a geographically defined population of preschool children.

DESIGN, SETTING, AND PARTICIPANTS

Survey conducted July 1998 to June 1999 in Staffordshire, England. The area's 15 500 children aged 2.5 to 6.5 years were screened for developmental problems. Children with symptoms suggestive of a PDD were intensively assessed by a multidisciplinary team, which conducted standardized diagnostic interviews and administered psychometric tests.

MAIN OUTCOME MEASURE

Prevalence estimates for subtypes of PDDs.

RESULTS

A total of 97 children (79.4% male) were confirmed to have a PDD. The prevalence of PDDs was estimated to be 62.6 (95% confidence interval, 50.8-76.3) per 10 000 children. Prevalences were 16.8 per 10 000 for autistic disorder and 45.8 per 10 000 for other PDDs. The mean age at diagnosis was 41 months, and 81% were originally referred by health visitors (nurse specialists). Of the 97 children with a PDD, 25.8% had some degree of mental retardation and 9.3% had an associated medical condition.

CONCLUSIONS

Our results suggest that rates of PDD are higher than previously reported. Methodological limitations in existing epidemiological investigations preclude interpretation of recent high rates as indicative of increased incidence of these disorders although this hypothesis requires further rigorous testing. Attention is nevertheless drawn to the important needs of a substantial minority of preschool children.

Accelerated telomere shortening following allogeneic transplantation is independent of the cell source and occurs within the first year post transplant

Telomere shortening has been documented in the blood cells of recipients of allogeneic bone marrow transplants compared with their donors. Allogeneic peripheral blood progenitor cells (PBPCs) have been increasingly used as an alternative to bone marrow. Their advantages include earlier engraftment and immune reconstitution following transplantation. We have measured telomere length of neutrophils and T cells in fully engrafted recipients of allogeneic bone marrow (n = 19) and allogeneic PBPC (n = 17) and also measured sequential telomere length in four patients after transplantation. Overall, significant telomere shortening occurred in recipients in neutrophils (0.3 kb, P < 0.001) and T cells (0.2 kb, P = 0.045). The data demonstrate that first, the degree of shortening was the same for BM and PBPC transplants and was not related to the time taken to engraft neutrophils and platelets and second, telomere shortening occurs in the first year post transplant without further shortening during the period of observation. These data suggest that the superiority of engraftment seen in PBPC transplants is independent of telomere shortening and other mechanisms such as homing or seeding may be more important.

Microsatellite instability in squamous cell carcinoma of head and neck from the Indian patient population

Genomic instability in simple repeated sequences has been observed in several human cancers. We have analyzed 50 squamous cell carcinomas of the head and neck (SCCHN) and 5 pre-malignant severe dysplastic tissues from Indian patient populations for microsatellite instability in 18 different loci spread over eight different chromosomes. Among the tumors analyzed, 45% exhibited instability at two or more loci, and 15% exhibited instability at 40% of the markers tested. Similar analysis of SCCHN tumors from other populations (British, American and French) showed much less frequency of instability. SCCHN tumors in the present study did not show any instability in the mononucleotide repeat sequences. There is also a clear distinction in the nature of the instability in these tumors in comparison with colorectal tumors. These results suggest that the underlying mechanism generating this type of instability is different from those reported for colorectal tumors.