A comparison of antibody testing, permeability testing, and zonulin levels with small-bowel biopsy in celiac disease patients on a gluten-free diet

Active celiac disease is associated with positive endomysial (EMA) and tissue transglutaminase (TTG) antibodies, elevated zonulin levels, and increased intestinal permeability. There is little known about what happens to these immunologic and structural abnormalities in patients on a gluten-free diet and their correlation with small-bowel biopsy changes. Adult patients previously diagnosed with celiac disease and on a gluten-free diet for greater than 1 year were considered for the study. All patients underwent the following: measurement of EMA and TTG antibodies, serum zonulin levels, intestinal permeability (IP) testing with lactulose/mannitol ratios, food diary analysis for gluten ingestion and small- bowel biopsy. A total of 21 patients on a gluten-free diet for a mean of 9.7 years completed the study. There were ten patients who had normalization of intestinal biopsies, IP and TTG, and EM antibodies. Six patients had Marsh type 2 or 3 lesions and all had either abnormal IP (5/6) or TTG antibody (4/6). In patients with Marsh type 3 lesions, there was a correlation between IP and zonulin levels. A subgroup of patients with celiac disease on a gluten-free diet has complete normalization of intestinal biopsies, intestinal permeability defects, and antibody levels. Patients with Marsh type 3 lesions have abnormal TTG antibodies and intestinal permeability with zonulin levels that correlate with IP. These abnormalities may be due to continued gluten ingestion. Further study is needed to determine the clinical utility of TTG antibodies and IP testing in following patients with celiac disease.

The location of constitutional neurofibromatosis 2 (NF2) splice site mutations is associated with the severity of NF2

Neurofibromatosis 2 (NF2) patients with constitutional splice site NF2 mutations have greater variability in disease severity than NF2 patients with other types of mutations; the cause of this variability is unknown. We evaluated genotype-phenotype correlations, with particular focus on the location of splice site mutations, using mutation and clinical information on 831 patients from 528 NF2 families with identified constitutional NF2 mutations. The clinical characteristics examined were age at onset of symptoms of NF2 and number of intracranial meningiomas, which are the primary indices of the severity of NF2. Two regression models were used to analyse genotype-phenotype correlations. People with splice site mutations in exons 1-5 had more severe disease than those with splice site mutations in exons 11-15. This result is compatible with studies showing that exons 2 and 3 are required for self-association of the amino terminal of the NF2 protein in vitro, and that deletions of exons 2 and 3 in transgenic and knockout mouse models of NF2 cause a high prevalence of Schwann cell derived tumours.

Methodological issues in longitudinal studies: vestibular schwannoma growth rates in neurofibromatosis 2

Four longitudinal studies of vestibular schwannoma (VS) growth rates in neurofibromatosis 2 (NF2) have yielded very different results on the relationship of VS growth rates to age. The studies had different patient eligibility criteria, indices of VS growth rates, VS volumetric methods, and sample sizes. We reanalysed data from two of the longitudinal studies and used data from the population based United Kingdom NF2 Registry to determine the most likely reason for the different results and the actual relationship of VS growth rates to age. We found that the eligibility criterion in one study caused selection bias for slower growing VS. The proper interpretation of the results from the four studies is that VS growth rates in NF2 are highly variable but tend to decrease with increasing age. Clinical trials for VS in NF2 should focus on younger patients because VS growth rates tend to decrease with increasing age, and because faster growing VS are more likely to be excised with increasing age than slower growing VS.

Intestinal permeability in long-term follow-up of patients with celiac disease on a gluten-free diet

Intestinal permeability is frequently abnormal in patients with celiac disease. The long-term effect of a gluten-free diet on intestinal permeability and the correlation of intestinal permeability with a gluten-free diet are not known. The objectives of this study were to determine the responses of intestinal permeability and antibody testing to gluten free diet and the degree of correlation of these measurements with gluten ingestion. In this prospective study, patients with celiac disease were divided into three groups based on length of time on a gluten-free diet: Group A, < 1 month; Group B, 1 month-1 year; Group C, > 1 year. Patients in Groups B and C were tested at baseline and at 4-12 weeks later for the following: lactulose/mannitol intestinal permeability, endomysial antibody, and 3-day food record. Permeability tests were also performed in Group A and control subjects. Intestinal permeability was elevated in newly diagnosed celiac disease and in individuals on a gluten-free diet for less than 1 year. Intestinal permeability was normal in 80% at visit 1 and 87% at visit 2 in individuals with celiac disease on a gluten-free diet for more than a year. Trace gluten ingestion was associated with increased intestinal permeability on visit 2 (P = 0.0480). The sensitivity of detecting gluten ingestion as measured by a 3-day food record was higher for permeability testing (29 and 36%) compared with endomysial antibody testing (18 and 18%) for visits 1 and 2, respectively. Intestinal permeability normalizes in the majority of individuals with celiac disease on a gluten-free diet. Gluten ingestion as measured by a 3-day food record correlates with intestinal permeability measurements. The role of permeability testing in the follow-up of patients with celiac disease warrants further investigation.

Primitive roles for inhibitory interneurons in developing frog spinal cord

Understanding the neuronal networks in the mammal spinal cord is hampered by the diversity of neurons and their connections. The simpler networks in developing lower vertebrates may offer insights into basic organization. To investigate the function of spinal inhibitory interneurons in Xenopus tadpoles, paired whole-cell recordings were used. We show directly that one class of interneuron, with distinctive anatomy, produces glycinergic, negative feedback inhibition that can limit firing in motoneurons and interneurons of the central pattern generator during swimming. These same neurons also produce inhibitory gating of sensory pathways during swimming. This discovery raises the possibility that some classes of interneuron, with distinct functions later in development, may differentiate from an earlier class in which these functions are shared. Preliminary evidence suggests that these inhibitory interneurons express the transcription factor engrailed, supporting a probable homology with interneurons in developing zebrafish that also express engrailed and have very similar anatomy and functions.

Intrafamilial correlation of clinical manifestations in neurofibromatosis 2 (NF2)

Measuring correlation in clinical traits among relatives is important to our understanding of the causes of variable expressivity in Mendelian diseases. Random effects models are widely used to estimate intrafamilial correlations, but such models have limitations. We incorporated survival techniques into a random effects model so that it can be used to estimate intrafamilial correlations in continuous variables with right censoring, such as age at onset. We also describe a negative-binomial gamma mixture model to determine intrafamilial correlations of discrete (e.g., count) data. We demonstrate the utility of these methods by analyzing intrafamilial correlations among patients with neurofibromatosis 2 (NF2), an autosomal-dominant disease caused by mutations of the NF2 tumor-suppressor gene. We estimated intrafamilial correlations in age at first symptom of NF2, age at onset of hearing loss, and number of intracranial meningiomas in 390 NF2 nonprobands from 153 unrelated families. A significant intrafamilial correlation was observed for each of the three features: age at onset (0.35; 95% confidence interval (CI) 0.23-0.47), age at onset of hearing loss (0.51; 95% CI, 0.35-0.64), and number of meninginomas (0.29; 95% CI, 0.15-0.43). Significant correlations were also observed for age at first symptom within NF2 families with truncating mutations (0.41; 95% CI, 0.06-0.68) or splice-site mutations (0.29; 95% CI, 0.03-0.51), for age at onset of hearing loss within families with missense mutations (0.67; 95% CI, 0.18-0.89), and for number of meningiomas within families with splice-site mutations (0.39; 95% CI, 0.13-0.66). Our findings are consistent with effects of both allelic and nonallelic familial factors on the clinical variability of NF2.

C-nociceptor activation of hypothalamic neurones and the columnar organisation of their projections to the periaqueductal grey in the rat

The induction of Fos protein was used to localise hypothalamic neurones activated by ramps of noxious skin heating delivered at a rate of 2.5 degrees C s(-1) to preferentially activate C-nociceptors. This was combined with retrograde transport of cholera toxin subunit B from identified 'pressor' and 'depressor' sites in the dorsolateral/lateral or the ventrolateral columns of the periaqueductal grey. Fos-positive neurones were found throughout the rostral hypothalamus. Despite this wide distribution, those neurones double labelled retrogradely from the periaqueductal grey were focused in the lateral area of the anterior hypothalamus. More than 20 % of Fos-positive neurones in this region projected to depressor sites in the ventrolateral periaqueductal grey, and 10 % projected to its dorsolateral/lateral sector. These results are discussed in relation to the peripheral inputs to hypothalamic-midbrain pathways and their role in the cardiovascular responses to different components of the pain signal.

Noxious somatic inputs to hypothalamic-midbrain projection neurones: a comparison of the columnar organisation of somatic and visceral inputs to the periaqueductal grey in the rat

The induction of Fos protein was used to localise hypothalamic neurones activated by noxious somatic stimulation. This was combined with retrograde transport of fluorescent latex microspheres from identified 'pressor' and 'depressor' sites in the dorsolateral/lateral or ventrolateral columns of the periaqueductal grey (PAG). Fos-positive neurones were found throughout the rostral hypothalamus. Of those neurones activated by noxious somatic stimuli that projected to the PAG all but one was retrogradely labelled from sites that included the lateral column. Only one neurone was double labelled following injection of tracer at a depressor site in the ventrolateral PAG. This is in marked contrast to visceroresponsive hypothalamic neurones, a larger proportion of which project to the PAG and which, as reported previously, preferentially target depressor sites in the ventrolateral sector. These results are discussed in relation to the roles of the anterior hypothalamus and the different functional columns of the PAG in co-ordinating autonomic and sensory functions in response to nociceptive inputs originating in different peripheral domains.

Intramedullary and spinal canal tumors in patients with neurofibromatosis 2: MR imaging findings and correlation with genotype

PURPOSE

To determine the appearance of spinal tumors on magnetic resonance (MR) images of patients with neurofibromatosis 2 (NF2), to assess the biologic behavior of these tumors, and to determine the correlation between NF2 germline mutations and these tumors.

MATERIALS AND METHODS

Spinal MR images in 49 patients with NF2 were reviewed retrospectively. Intramedullary and intradural extramedullary tumors were counted, and imaging features and growth patterns of intramedullary tumors were determined. Medical records were reviewed for spinal tumor surgery. Data on spinal tumors and NF2 germline mutations in 37 patients from 19 families were analyzed for genotype-phenotype correlation.

RESULTS

Thirty-one patients (63%) had spinal tumors: Twenty-six (53%) had intramedullary tumors, 27 (55%) had intradural extramedullary tumors, and 22 (45%) had at least one tumor of each type. Three (12%) patients with intramedullary tumors versus 16 (59%) with extramedullary tumors had undergone surgery for the respective types of tumors. Compared with patients with all other types of mutations, a higher percentage of patients with nonsense and frameshift mutations had intramedullary tumors (P <.025); these patients also had higher mean numbers of all tumors (P <.001), intramedullary tumors (P <.001), and nerve sheath tumors (NSTs) (P <.001).

CONCLUSION

In patients with NF2 and spinal tumors, extramedullary tumors (predominantly NSTs) were present in higher numbers and were associated with more surgery than were intramedullary tumors. Our data suggest that the association between nonsense and frameshift mutations and severe NF2 may extend to specific categories of spinal tumors.

Chordoma: incidence and survival patterns in the United States, 1973-1995

BACKGROUND

Chordoma, a rare tumor arising from notochordal remnants, has been described to date only by single-institution case series or small population-based surveys.

METHODS

We used data from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute, 1973-1995, to calculate age-adjusted incidence and survival rates for 400 cases of microscopically confirmed chordoma and to derive information regarding case distribution and risk of second cancer.

RESULTS

The age-adjusted chordoma incidence rate (IR) of 0.08 per 100,000 was age-dependent, more common in males (IR 0.10) than females (IR 0.06) and rare among patients aged <40 years and blacks. Within the axial skeleton 32% of cases were cranial, 32.8% spinal and 29.2% sacral. Young age (<26 years; p = 0.0001) and female sex (p = 0.037) were associated with greater likelihood of cranial presentation. There was no overall increased risk for second primary cancers after chordoma. Median survival was 6.29 years; 5- and 10-year relative survival rates were 67.6% and 39.9%, respectively. Comparison with other bone sarcomas revealed racial disparities in incidence for the two developmental tumors, chordoma and Ewing's sarcoma.

CONCLUSIONS

This study provides new data regarding incidence and survival patterns of chordoma in the US. Additional epidemiologic studies are required to elucidate the genetic and environmental determinants underlying this rare, distinctive neoplasm.

The parental origin of new mutations in neurofibromatosis 2

Neurofibromatosis 2 (NF2) is an autosomal dominant disorder characterized by schwannomas and meningiomas that develop after inactivation of both copies of the NF2 gene. Approximately half of all patients with NF2 have unaffected parents and the disease results from new mutations at the NF2 locus. Loss of heterozygosity (LOH) in tumor specimens due to deletions covering the normal NF2 allele can be used to infer the haplotypes surrounding underlying mutations and determine the allelic origin of new mutations. We studied 71 sporadic NF2 patients using both LOH and pedigree analysis and compared the parental origin of the new mutation with the underlying molecular change. In the 45 informative individuals, 31 mutations (69%) were of paternal and 14 (31%) were of maternal origin (P=0.016). Comparison with corresponding constitutional mutations revealed no correlation between parental origin and the type or location of the mutations. However, in 4 of 6 patients with somatic mosaicism the NF2 mutation was of maternal origin. A slight parent of origin effect on severity of disease was found. Further clinical and molecular studies are needed to determine the basis of these unexpected observations.

Chronic hyperlipasemia caused by sarcoidosis

A chronically elevated lipase is a rare biochemical finding and has only previously been described in patients with malignancy and macrolipasemia. We report a case of chronic hyperlipasemia caused by sarcoidosis. The literature on pancreatic sarcoidosis is reviewed and the significance of lipase isoforms is discussed. Sarcoidosis needs to be considered in patients presenting with chronic hyperlipasemia.

Serotonergic transmission in the periaqueductal gray matter in relation to aversive behaviour: morphological evidence for direct modulatory effects on identified output neurons

Intracellular recordings were made from 21 cells in the dorsolateral periaqueductal gray matter in coronal midbrain slices. In the majority (n = 20) bath application of 5-hydroxytryptamine (30 or 150 mM) evoked either hyperpolarizing (n = 11) or depolarizing (n = 9) responses. Reconstructions of 11 neurons in the dorsolateral periaqueductal gray matter after filling with biocytin revealed a population of output neurons whose axons followed a dorsolateral trajectory towards the perimeter of the ipsilateral periaqueductal gray matter. In seven cells, the axon could be followed into the adjacent mesencephalic reticular formation. At the light microscopic level, immunostaining for 5-hydroxytryptamine revealed immunoreactive processes throughout the dorsolateral periaqueductal gray matter but no labelled somata or dendrites. Close associations (i.e. no discernible gap) were observed between serotonergic profiles and the somata and dendrites of biocytin-filled cells. At the ultrastructural level, serial sections through 21 appositions on to biocytin-filled dendrites in three slices revealed 19 true appositions (i.e. having closely parallel plasma membranes with no intervening glial cell profiles) with the biocytin-filled dendrite. Only four of the appositions (21%) showed evidence of synaptic specializations which included aggregations of synaptic vesicles, and some thickening of the apposing membrane. The dense reaction product in the biocytin-filled cells precluded identification of the ultrastructure of postsynaptic elements. However, examination of contacts between 5-hydroxytryptamine-immunoreactive profiles and unlabelled elements in material taken from the contralateral side of the periaqueductal gray matter (i.e. no biocytin present) or in material taken from perfusion-fixed whole brain, in which ultrastructural preservation was superior compared with slices, revealed a similar incidence (21% and 23%, respectively) of synaptic specializations. The data indicate that serotonergic transmission on to output neurons in the dorsolateral periaqueductal gray matter is largely mediated by non-junctional contacts, suggesting that the actions of 5-hydroxytryptamine on these cells are mediated predominantly by volume rather than wiring transmission.

Does jejunal feeding with a polymeric immune-enhancing formula increase pancreatic exocrine output as compared with TPN? A case report

This case report compares the pancreatic output with different feeding regimes in a patient who underwent a partial pancreatectomy for carcinoma of the ampulla of Vater. A postoperative secretin stimulation test demonstrated significant pancreatic reserve. There was no difference in pancreatic exocrine secretion when the patient was fed jejunally with a polymeric immune-enhancing formula or supported with two different formulations of total parenteral nutrition. This result suggests that jejunal infusion of a polymeric immune-enhancing formula may be safe to administer in patients with acute pancreatitis.

Allelic expression of the NF2 gene in neurofibromatosis 2 and schwannomatosis

Neurofibromatosis type 2 (NF2) is a genetic disorder characterized by formation of multiple schwannomas and meningiomas due to inactivating mutations in the NF2 tumor suppressor gene on chromosome 22. We describe a polymorphism in the 3' untranslated region of the NF2 gene that is informative in about one-third of individuals. This polymorphism permitted an assessment of the relative expression of NF2 transcripts in lymphoblastoid cell RNA from 22 unrelated NF2 patients heterozygous for a germline NF2 mutation, along with 6 schwannomatosis patients, and 14 unaffected controls. Unequal allelic expression (1.8- to 20-fold) was detected in 15 of the NF2 cases, but in none of the schwannomatosis or control individuals. Underexpression of the NF2 mutant allele was documented for all 6 nonsense or frameshift mutations, 3 of 6 splice mutations, and 1 of 4 missense mutations, which, unexpectedly, was shown to alter the NF2 transcript and create a premature stop codon. In contrast, equal expression or slight overexpression of NF2 mutant alleles was observed for 2 in-frame deletions, 2 splice alterations, and 3 missense mutations. In the remaining 5 cases, the allele representing the mutant transcript was not known. Thus, truncating NF2 mutations, which are the most frequent alterations in NF2 patients and NF2-associated tumors, were associated with underexpression of the mutant allele, whereas the less common in-frame alterations usually showed normal or slight overexpression of the mutant transcript.

Genetic variation in the 3' untranslated region of the neurofibromatosis 1 gene: application to unequal allelic expression

Neurofibromatosis type 1 (NF1) is a common genetic disorder caused by inactivation of neurofibromin, a protein capable of modulating signal transduction by activating Ras-GTPase activity. We have used cDNA cloning and Northern blot analysis to confirm the NF1 gene produces alternatively polyadenylated mRNAs with 3' untranslated regions (3' UTR) that show striking evolutionary conservation. Scanning of the 3'UTRs for genetic variation revealed three common sequence polymorphisms (> 30% heterozygosity), one less informative polymorphism (approximately 5% heterozygosity) and one rare variant (1/144 chromosomes). These differences were used to examine relative levels of expression of normal and mutant NF1 alleles in lymphoblast cell lines and in one case, autopsy tissue, from patients with NF1. Unequal allelic expression (up to 4-fold) was observed in a subset of both sporadic and familial NF1 cases. Where linkage phase could be determined, the allele segregating with the disorder displayed a relative reduction in expression. However, the magnitude of this effect was variable suggesting the operation of additional, non-genetic factors in determining the degree of relative expression of the mutant allele.

Immunocytochemical localization of GnRH precursor in the hypothalamus of European starlings during sexual maturation and photorefractoriness

Immunocytochemistry with quantitative image analysis, for both GnRH and its precursor proGnRH-GAP, was used in male European starlings (Sturnus vulgaris) to investigate four stages of a photoperiodically-induced reproductive cycle. Four different groups of birds were examined: photosensitive buy sexually immature, sexually mature, undergoing gonadal regression, and after the completion of regression and fully photorefractory. The size of cells staining for GnRH and proGnRH-GAP increased during gonadal maturation. A reduction in the number of cells staining for GnRH and the size of cells staining for both GnRH and proGnRH-GAP occurred during gonadal regression, though staining for GnRH and proGnRH-GAP in the median eminence remained high at this stage. Birds examined after completion of regression showed significantly reduced staining for both GnRH and its precursor. These observations suggest that photorefractoriness is promoted by a reduction in proGnRH-GAP production and in GnRH synthesis, rather than requiring inhibition of release of GnRH at the median eminence.

Transcutaneous bilirubinometry: its role in the assessment of neonatal jaundice

OBJECTIVE

To review the literature on transcutaneous bilirubinometry so that its exact role in the prevention of kernicterus or bilirubin encephalopathy could be determined.

DESIGN AND METHODS

Literature searches were done in Medline and Current Contents.

RESULTS

It is estimated that about 50% of newborns have an episode of jaundice in the first few days of life. Six percent of newborns may develop hyperbilirubinemia (> 220 mumol/L), which can potentially cause bilirubin encephalopathy or kernicterus, a severe neonatal disease. In the past, serum bilirubin (SB) has been the preferred method of detecting hyperbilirubinemia in newborns. The ordering of SB in neonates is based on visual evaluation by either physicians or nursing staff. Skin puncture collection of blood exposes the neonate to trauma and risk of infection. A noninvasive device for predicting serum bilirubin levels in newborns diminishes the need to do skin punctures. One such device that has been very extensively studied is the Minolta AirShields Jaundice Meter. It is a portable light-weight instrument that uses reflectance measurements on the skin to determine the amount of yellow color present in the skin, namely transcutaneous bilirubin (TcB). Although the TcB measurements correlate well with serum bilirubin (SB) levels, they cannot accurately predict serum bilirubin because of error related to a variety of factors.

CONCLUSIONS

TcB cannot be used directly to make decisions about transfusions or phototherapy in neonates. It is a good tool for screening neonates to determine when a laboratory measurement of serum bilirubin is needed. Such a practice requires careful selection of the decision level so that false-negative TcB values do not prevent appropriate serum bilirubin tests from being done.

Clinical impact of transcutaneous bilirubinometry as an adjunctive screen for hyperbilirubinemia

OBJECTIVE

To determine what the clinical impact would be of implementing a jaundice meter for use in a busy neonatal service as an adjunctive screening tool for hyperbilirubinemia.

DESIGN AND METHODS

Test utilization data was collected for a 6-month period to determine how neonatal bilirubin was utilized in this hospital. The jaundice meter was evaluated in a study population of healthy term infants. The performance characteristics of the meter and the test utilization data were used to predict the clinical impact a meter could have on screening for hyperbilirubinemia.

RESULTS

Utilization data indicated that about 60% of all single bilirubin neonatal testing (i.e., bilirubin only ordered) was done by normal nurseries. A jaundice meter cutoff decision reading of 17 was shown to have a sensitivity of 100% and a specificity of 68% for hyperbilirubinemia (> 260 mumol/L) in a study population of healthy term infants. From this data, it was estimated that use of a jaundice meter could eliminate 43% of the single (i.e., not combined with other tests) bilirubin tests done on healthy term neonates with no prior exposure to phototherapy. This constitutes an overall 20% reduction in bilirubin testing in normal nurseries when testing done on babies exposed to phototherapy and combined bilirubin testing are taken into consideration. Additionally, it was shown that there would be an improvement of 9% in the prediction of hyperbilirubinemia without loss of 100% sensitivity.

CONCLUSION

Use of a jaundice meter in normal nurseries as an adjunctive screening tool enhances patient care by reducing the overall blood procurement rate in normal nurseries by 20% and increasing screening efficiency for significant hyperbilirubinemia by 5%.

Multiple schwannomas and meningiomas associated with irradiation in childhood

OBJECTIVE

To determine the pattern of neural tumors (schwannomas, vestibular schwannomas [acoustic neuromas], and meningiomas) that developed in 3013 people who received radiation treatment with x-ray beam therapy for benign conditions of the head and neck area before their 16th birthday.

METHODS

The surgical and pathology reports and pathology slides were reviewed for all neural tumors in the cohort. Patients with more than 1 neural tumor were compared with those with 1 neural tumor and those with no neural tumors.

RESULTS

There were 7 patients with multiple neural tumors and 63 with single neural tumors. The distribution of tumors in these 2 groups differed. The group with multiple tumors had more spinal nerve root schwannomas, while the group with single tumors had more cranial nerve schwannomas. Six of the 7 patients did not meet the diagnostic criteria for neurofibromatosis type 2.

CONCLUSIONS

Our findings suggest that host factors that increase susceptibility to radiation may be involved in the development of the multiple neural tumors. Clinically, patients with multiple neural tumors who do not meet the diagnostic criteria for neurofibromatosis type 2 should be questioned about radiation exposure. If exposure is confirmed, then screening for other radiation-related tumors should be initiated.

Germ-line mutations in the neurofibromatosis 2 gene: correlations with disease severity and retinal abnormalities

Neurofibromatosis 2 (NF2) features bilateral vestibular schwannomas, other benign neural tumors, and cataracts. Patients in some families develop many tumors at an early age and have rapid clinical progression, whereas in other families, patients may not have symptoms until much later and vestibular schwannomas may be the only tumors. The NF2 gene has been cloned from chromosome 22q; most identified germ-line mutations result in a truncated protein and severe NF2. To look for additional mutations and clinical correlations, we used SSCP analysis to screen DNA from 32 unrelated patients. We identified 20 different mutations in 21 patients (66%): 10 nonsense mutations, 2 frameshifts, 7 splice-site mutations, and 1 large in-frame deletion. Clinical information on 47 patients from the 21 families included ages at onset and at diagnosis, numbers of meningiomas, spinal and skin tumors, and presence of cataracts and retinal abnormalities. We compared clinical findings in patients with nonsense or frameshift mutations to those with splice-site mutations. When each patient was considered as an independent random event, the two groups differed (P < or = .05) for nearly every variable. Patients with nonsense or frameshift mutations were younger at onset and at diagnosis and had a higher frequency and mean number of tumors, supporting the correlation between nonsense and frameshift mutations and severe NF2. When each family was considered as an independent random event, statistically significant differences between the two groups were observed only for mean ages at onset and at diagnosis. A larger data set is needed to resolve these discrepancies. We observed retinal hamartomas and/or epiretinal membranes in nine patients from five families with four different nonsense mutations. This finding, which may represent a new genotype-phenotype correlation, merits further study.

A point mutation associated with a severe phenotype of neurofibromatosis 2

Neurofibromatosis 2 (NF2) is an autosomal dominant disease characterized by bilateral vestibular schwannomas and other nonmalignant tumors of the brain, spinal cord, and peripheral nerves. Although the average age of onset of NF2 is 20 years, some individuals may become symptomatic in childhood. We studied 5 unrelated NF2 patients who became symptomatic before age 13. All 5 had multiple tumors in addition to vestibular schwannoma, and none had a positive family history. Sequence analysis of the NF2 gene revealed identical nonsense mutation of exon 6 in 3 patients. Because this mutation destroys a restriction enzyme recognition site, genomic DNA from the 2 other children was directly tested for this change and identical alterations were detected. Although the work of our laboratory and others has not, in general, detected identical mutations in unrelated patients, this mutation seems to occur particularly frequently in the pediatric population and thus may be associated with an especially severe phenotype. Restriction analysis in children with NF2 may be a cost effective way of identifying their mutation. Further work is needed to characterize the effects of this change on the NF2 protein product and its relationship to this severe phenotype.

Glutamatergic projections from the rostral hypothalamus to the periaqueductal grey

Retrograde transport of fluorescent latex microspheres was combined with immunocytochemistry for glutamate to determine the organization of the projections from glutamate-containing neurones in the rostral hypothalamus to the different subdivisions of the periaqueductal grey (PAG). Double-labelled neurones, i.e. neurones immunoreactive for glutamate and projecting to the PAG, were found throughout the rostral hypothalamus. There were no apparent differences, however, in the origins of presumed glutamatergic projections from the rostral hypothalamus to the different subdivisions of the PAG.

Lymphangiosarcoma in late-onset hereditary lymphedema: case report and nosological implications

Hereditary lymphedemas that are not associated with other malformations usually affect the lower limbs and are inherited in an autosomal dominant fashion. These non-syndromic hereditary lymphedemas are categorized by their age of onset, being either congenital (Milroy disease) or having an onset in childhood or around puberty (Meige disease). We describe a family in which three individuals in three generations had unusually late onset of lymphedema in their mid-twenties or thirties. The proband additionally developed a very rare lymphangiosarcoma. This tumor, usually associated with post-mastectomy lymphedema, has not been described in late-onset hereditary lymphedema. Because of an unusually high incidence of multiple primary tumors in association with lymphangiosarcoma in the literature (approximately 10%) and the proband's own familial cancer background, we speculate that an inherited predisposition to malignancy may underlie the development of lymphedema-associated lymphangiosarcoma.

Survival after retinoblastoma: long-term consequences and family history of cancer

Retinoblastoma (Rb) is a rare childhood tumor of the eye. In the heritable form, tumors are often bilateral and survivors have a greatly increased risk both for a second malignancy and for having children with Rb. Familial patterns of both cancer and birth defects are poorly understood in families with a heritable cancer, and little is known of the ways that a heritable cancer affects the lives of long-term survivors. To find out more about these and other issues in the lives of long-term survivors of childhood and adolescent cancer, we interviewed 56 adult survivors of retinoblastoma (15 with the heritable form) and 84 brothers and sisters as controls, who formed part of a large retrospective cohort study. Rb survivors were interviewed between 1980 and 1983, when they were 30 years old on average. Types of employment and health problems did not differ between survivors and controls, regardless of sight, but the income of blind survivors was considerably less than that of partially sighted survivors. Despite similar marriage rates, fewer survivors than controls reported a pregnancy (RR = 0.45; 95% CI; 0.24-0.83 for both sexes combined). Parents of children with heritable Rb seemed more likely to have had cancer than parents in families with nonheritable Rb (P = 0.06), and mothers were more likely than fathers to be affected (P = 0.01). This small series suggests that having retinoblastoma may have many long-term consequences, reaching beyond genetic and physical effects to touch family life and income attainment and the health of other family members. Follow-up of more modern cohorts and the use of molecular tools will clarify the long-term consequences of more recent therapies, and patterns of familiar cancer.

Neurofibromatosis 2 (NF2): clinical characteristics of 63 affected individuals and clinical evidence for heterogeneity

To determine the spectrum of manifestations in neurofibromatosis 2 (NF2) and to assess possible heterogeneity, we evaluated 63 affected individuals from 32 families. Work-up included skin and neurologic examinations, audiometry, a complete ophthalmology examination with slit-lamp biomicroscopy of the lens and fundus, and gadolinium-enhanced MRI of the brain and, in some, of the spine. Mean age-at-onset in 58 individuals was 20.3 years; initial symptoms resulted from vestibular schwannomas (44.4%), other CNS tumors (22.2%), skin tumors (12.7%), and ocular manifestations including cataracts and retinal hamartomas (12.7%). Five asymptomatic individuals were diagnosed through screening. Vestibular schwannomas were documented in 62 individuals (98.4%); other findings included cataracts (81.0%), skin tumors (67.7%), spinal tumors (67.4%), and meningiomas (49.2%). Usually, clinical manifestations and course were similar within families but differed among families. To assess possible heterogeneity, we assigned affected individuals to three proposed subtypes (representing mild, intermediate, and severe NF2) based on age-at-onset, presence or absence of CNS tumors other than vestibular schwannomas, and presence or absence of retinal hamartomas. Comparisons among the three subtypes for many clinical parameters demonstrated that patients in the mild subtype differed from those in the other two subtypes for most parameters, but that none of the parameters distinguished patients in the intermediate subtype from those in the severe subtype. Thus, there are likely two rather than three subtypes of NF2. Classification of patients to subtype may aid in counseling about long-term prognosis and in formulating individualized guidelines for medical surveillance.

In vitro radiosensitivity of fibroblasts from thyroid and skin cancer patients treated with X-rays for tinea capitis

To investigate the hypothesis that persons who developed thyroid or skin cancer subsequent to scalp irradiation for tinea capitis are particularly sensitive to radiation, possibly because of a high frequency of ataxia-telangiectasia, we used an in vitro cell survival assay to evaluate radiosensitivity of their fibroblast cell strains. Study subjects were selected from a cohort of 10,834 Israelis irradiated during childhood for tinea capitis. Skin fibroblasts were obtained from thyroid and skin cancer patients (cases) as well as a sample of subjects who did not have cancer (controls). Fibroblasts were cultured and then loss of colony-forming ability as a result of acute X-irradiation was evaluated. Comparison of survival curve parameters (mean inverse of the slope and the dose needed to reduce colony survival to 10%) between 12 thyroid cancer and 12 control strains showed no differences (P > 0.5). A slightly increased radiation sensitivity of the skin cancer cases compared with their controls was observed. Although based on few subjects (14 cases and 11 controls), the findings were similar whether the mean inverse of the slope (P = 0.06) or the dose needed to reduce colony survival to 10% (P = 0.05) was evaluated. However, because of the small size of the study and potential errors inherent in survival assays, our finding that cell strains derived from patients who developed skin cancer exhibit enhanced radiosensitivity should be viewed as preliminary and interpreted cautiously.

Presymptomatic diagnosis for neurofibromatosis 2 with chromosome 22 markers

Neurofibromatosis 2 (NF2) is a dominantly inherited disorder characterized by multiple tumors of the central nervous system, predominantly bilateral vestibular schwannomas. The gene for NF2 is located in the chromosomal region 22q12 between the loci D22S1 and D22S28. We have performed genetic linkage analysis on 13 NF2 families with a total of nine polymorphic DNA markers, including five which we have recently mapped to this region. Two loci, D22S32 and NEFH, are linked to the NF2 locus at 0% recombination (lod scores of 6.03 and 4.28, respectively). By multipoint linkage analysis, we assign the NF2 gene to an interval of 7 cM, between the loci D22S212 and D22S28. We have used this set of nine markers to construct chromosome 22 haplotypes for the 82 at-risk individuals in this pedigree set. It has been possible to determine, with a high degree of certainty, the carrier status of 70 (85%) of these at-risk individuals. Risk prediction was possible in every case where DNA was available from both parents. Fifty-three of the 70 (76%) informative individuals were assigned decreased risks of being carriers. The use of chromosome 22 probes for risk assessment should result in a greatly reduced number of individuals who require periodic screening for NF2.

Ultrastructural evidence for changes in synaptic input to the hypothalamic luteinizing hormone-releasing hormone neurons in photosensitive and photorefractory starlings

Neural input to the hypothalamic luteinizing hormone-releasing hormone (LHRH) neurons was investigated in male starlings (Sturnus vulgaris) using electron microscopy combined with immunocytochemistry. Birds (4 to 6 in each group) were sampled at four stages of a photoperiodically induced reproductive cycle: (a) sexually immature but photosensitive, under short days; (b) during sexual maturation after 7 to 25 long days; (c) during gonadal regression after 35 to 50 long days; and (d) when fully photorefractory after 11 months exposure to long days. The length of the perikaryal membrane, the number and length of axo-somatic terminals in contact with it and the number and length of synaptic modifications within the terminals were measured for a minimum of six LHRH neurons in each brain. The number of axo-somatic terminals per neuron and the number per unit length of perikaryal membrane did not differ in birds of groups (a), (b) and (c), but was significantly greater (P < 0.05) in the fully refractory birds (group d). Similarly, the number of synaptic modifications was significantly greater (P < 0.05) in group (d) than in the other groups. These results are consistent with increased neural input to the LHRH perikarya in photorefractory birds after prolonged exposure to long days, although there was no indication of a change in input at the time of gonadal regression.

Lens opacities in neurofibromatosis 2: further significant correlations

This prospective study of 96 individuals from 29 families with neurofibromatosis 2, 49 of whom were affected, confirms in an extended series the previously reported association between posterior subcapsular/capsular cataract and neurofibromatosis 2. Posterior subcapsular/capsular cataracts were found in 36 (80%) of the 45 affected individuals (four individuals were excluded from statistical analyses). In addition, the association of peripheral cortical lens opacities with neurofibromatosis 2 was found to be statistically significant. Seventeen of the patients with neurofibromatosis 2 (37.8%) had peripheral cortical cataracts in comparison with none of the unaffected family members (p < 0.0001). In three patients peripheral cortical opacities were present despite the absence of posterior subcapsular/capsular cataracts. These findings support the inclusion of cortical cataracts of early onset, in addition to posterior subcapsular/capsular cataracts, in the diagnostic criteria of neurofibromatosis 2.

A novel moesin-, ezrin-, radixin-like gene is a candidate for the neurofibromatosis 2 tumor suppressor

Neurofibromatosis 2 (NF2) is a dominantly inherited disorder characterized by the occurrence of bilateral vestibular schwannomas and other central nervous system tumors including multiple meningiomas. Genetic linkage studies and investigations of both sporadic and familial tumors suggest that NF2 is caused by inactivation of a tumor suppressor gene in chromosome 22q12. We have identified a candidate gene for the NF2 tumor suppressor that has suffered nonoverlapping deletions in DNA from two independent NF2 families and alterations in meningiomas from two unrelated NF2 patients. The candidate gene encodes a 587 amino acid protein with striking similarity to several members of a family of proteins proposed to link cytoskeletal components with proteins in the cell membrane. The NF2 gene may therefore constitute a novel class of tumor suppressor gene.

Neurofibromatosis type 2 appears to be a genetically homogeneous disease

Neurofibromatosis type 2 (NF2) is an autosomal dominant syndrome characterized by the development of vestibular schwannomas and other tumors of the nervous system, including cranial and spinal meningiomas, schwannomas, and ependymomas. The presence of bilateral vestibular schwannomas is sufficient for the diagnosis. Skin manifestations are less common than in neurofibromatosis type 1 (NF1; von Recklinghausen disease). The apparent clinical distinction between NF1 and NF2 has been confirmed at the level of the gene locus by linkage studies; the gene for NF1 maps to chromosome 17, whereas the gene for NF2 has been assigned (in a single family) to chromosome 22. To increase the precision of the genetic mapping of NF2 and to determine whether additional susceptibility loci exist, we have performed linkage analysis on 12 families with NF2 by using four polymorphic markers from chromosome 22 and a marker at the NF1 locus on chromosome 17. Our results confirm the assignment of the gene for NF2 to chromosome 22 and do not support the hypothesis of genetic heterogeneity. We believe that chromosome 22 markers can now be used for presymptomatic diagnosis in selected families. The NF2 gene is tightly linked to the D22S32 locus (maximum lod score 4.12; recombination fraction 0). A CA-repeat polymorphism at the CRYB2 locus was the most informative marker in our families (lod score 5.99), but because the observed recombination fraction between NF2 and CRYB2 was 10 cM, predictions using this marker will need to be interpreted with caution.

Hexokinase receptors: preferential enzyme binding in normal cells to nonmitochondrial sites and in transformed cells to mitochondrial sites

Hexokinase plays an important role in normal glucose-utilizing tissues like brain and kidney, and an even more important role in highly malignant cancer cells where it is markedly overexpressed. In both cell types, normal and transformed, a significant portion of the total hexokinase activity is bound to particulate material that sediments upon differential centrifugation with the crude "mitochondrial" fraction. In the case of brain, particulate binding may constitute most of the total hexokinase activity of the cell, and in highly malignant tumor cells as much as 80 percent of the total. When a variety of techniques are rigorously applied to better define the particulate location of hexokinase within the crude "mitochondrial fraction," a striking difference is observed between the distribution of hexokinase in normal and transformed cells. Significantly, particulate hexokinase found in rat brain, kidney, or liver consistently distributes with nonmitochondrial membrane markers whereas the particulate hexokinase of highly glycolytic hepatoma cells distributes with outer mitochondrial membrane markers. These studies indicate that within normal tissues hexokinase binds preferentially to nonmitochondrial receptor sites but upon transformation of such cells to yield poorly differentiated, highly malignant tumors, the overexpressed enzyme binds preferentially to outer mitochondrial membrane receptors. These studies, taken together with the well-known observation that, once solubilized, the particulate hexokinase from a normal tissue can bind to isolated mitochondria, are consistent with the presence in normal tissues of at least two different types of particulate receptors for hexokinase with different subcellular locations. A model which explains this unique transformation-dependent shift in the intracellular location of hexokinase is proposed.

Familial occurrence of combined pigment epithelial and retinal hamartomas associated with neurofibromatosis 2

Combined pigment epithelial and retinal hamartomas are rare lesions that usually occur sporadically in individuals without systemic abnormalities. However, they have been reported in isolated patients with neurofibromatosis 1 and 2. No familial cases have been reported. The cases of four patients with unilateral macular lesions from three consecutive generations of a single family are presented: two of the patients also have neurofibromatosis 2. The ophthalmoscopic appearance of their ocular lesions resembles combined pigment epithelial and retinal hamartomas. The morphologic differences in the lesions of these 4 patients, whose ages are 8 months, 5 years, 29 years, and 65 years, may serve to demonstrate the evolution of this type of hamartoma.

Relationship between head circumference and height in normal adults and in the nevoid basal cell carcinoma syndrome and neurofibromatosis type I

Occipitofrontal circumference (OFC) was strongly correlated with height in 72 normal Caucasian men (r = 0.28, P = 0.018) and 78 women (r = 0.53, P less than 0.0001). OFC:height ratios were approximately normally distributed in each sex with a mean of 0.326 (standard deviation [sd] = 0.0139) in males and 0.335 (sd = 0.0177) in females. Relative macrocephaly (an OFC greater than the 95th centile for height) was seen in seven of nine probands with the nevoid basal cell carcinoma syndrome (NBCC), eight of 32 non-probands with NBCC, three of four neurofibromatosis type 1 (NF1) probands, and six of nine non-probands with NF1. Thirty-one percent of the non-proband NBCC cases had OFC less than the 50th centile for height, while none of the NF1 cases had this finding. Head size appears to be related to proband status in NBCC, while the evidence suggests that NF1 is a true macrocephaly syndrome. Objective detection of relative abnormalities in head size may aid in syndrome delineation and diagnosis.

NIH conference. Neurofibromatosis 1 (Recklinghausen disease) and neurofibromatosis 2 (bilateral acoustic neurofibromatosis). An update

The neurofibromatoses comprise at least two autosomal dominant disorders affecting an estimated 100,000 Americans with clinical manifestations that may require care from every type of clinician. Neurofibromatosis 1 and neurofibromatosis 2 have in common the occurrence of many neurofibromas but are distinctly different clinical disorders. The disease genes are on different chromosomes. Magnetic resonance imaging, particularly with gadolinium enhancement, has generally supplanted other techniques for visualizing brain, spinal, and other neural tumors in both disorders. The technique has rekindled the controversy over the nature and frequency of optic pathway tumors in patients with neurofibromatosis 1 and has revealed, throughout the brains of young patients, bright lesions that have uncertain clinical consequences and unknown pathologic bases. In patients with neurofibromatosis 2, small acoustic neuromas can be seen, leading to the possibility of excision with preservation of hearing and facial nerve function. Abnormal hearing may occur to excess in patients with neurofibromatosis 1, but acoustic neuroma has never been documented. In patients with neurofibromatosis 2, a battery of audiologic tests has a high positive predictive power. Lisch nodules or iris hamartomas, probably a universal sign in adults with the neurofibromatosis 1 gene, cause no problem with vision. Posterior capsular lens opacity in patients with neurofibromatosis 2 is a helpful diagnostic sign and a potential source of additional handicap in persons at risk for impaired hearing. Progress in the clinical delineation of the disorders has been matched with considerable research into the still obscure pathogenesis of the disorders. Such rapid advances may necessitate reconsideration of the conclusions of the National Institutes of Health Consensus Development Conference on Neurofibromatosis, especially those on the categories of persons in which a neurofibromatosis should be considered and the need for caution in recommending surgery. Watchful waiting may often be the best management for acoustic neuromas in neurofibromatosis 2.

Glucose catabolism in brain. Intracellular localization of hexokinase

A major energy source in brain is glucose, which is committed to metabolism by hexokinase (Type I isozyme), an enzyme usually considered to be bound to the outer mitochondrial membrane. In this study, the subcellular location of hexokinase in brain has been rigorously investigated. Mitochondrial fractions containing hexokinase (greater than 500 milliunits/mg protein) were prepared by two different procedures, and then subjected to density gradient centrifugation before and after loading with barium phosphate, a technique designed to increase the density of the mitochondria. The gradient distribution patterns of both unloaded and loaded preparations show that brain hexokinase does not distribute exclusively with mitochondrial marker enzymes. This is particularly evident in the loaded preparations where there is a clear distinction between the peak activities of hexokinase and mitochondrial markers. The same observation was made when the mitochondrial fraction of either untreated or barium phosphate-loaded mitochondria was subjected to titration with digitonin. In fact, at concentrations of digitonin, which almost completely solubilize marker enzymes for both the inner and outer mitochondrial membranes, a significant fraction of the total hexokinase remains particulate bound. Electron microscopy confirmed that particulate material is still present under these conditions. Significantly, hexokinase is released from particulate material only at high concentrations of digitonin which solubilize the associated microsomal marker NADPH-cytochrome c reductase. Glucose 6-phosphate, which is known to release hexokinase from the brain "mitochondrial fraction" also releases hexokinase from this unidentified particulate component. These results on brain, a normal glucose utilizing tissue, differ from those obtained previously on highly glycolytic tumor cells where identical subfractionation procedures revealed a strictly outer mitochondrial membrane location for particulate hexokinase (Parry, D. M., and Pedersen, P. L. (1983) J. Biol. Chem. 258, 10904-10912). It is concluded that in brain, hexokinase has a greater propensity to localize at nonmitochondrial receptor sites than to those known to be associated with the outer mitochondrial membrane.

Sites of [3H]taurine Uptake in the Rat Substantia Nigra in Relation to the Release of Taurine from the Striatonigral Pathway

The autoradiographic localization of radiolabelled taurine taken up in the rat substantia nigra in vivo together with conditions of release of the [3H]taurine taken up into brain slices were studied to determine whether they are consistent with the hypothesis that taurine may act as a neurotransmitter in the striatonigral pathway. At the light microscopic level the main cellular elements that became radiolabelled following the injection of [3H]taurine into the substantia nigra could be identified as glial cells. Electron microscope autoradiography confirmed that a subpopulation of glial cells including astrocytes, pericytes, and oligodendrocytes were radiolabelled and that neuronal perikarya were not radiolabelled. In addition, axonal elements including both terminal and preterminal boutons were found to have silver grains overlying them and were thus considered to be radiolabelled. This was supported by a quantitative analysis of the distribution of the silver grains; whereas glial elements had a significantly higher number of grains associated with them than with any other structure, axonal elements had a significantly greater number of grains than dendritic structures. Release of the preloaded [3H]taurine from superfused slices of substantia nigra occurred in response to veratridine, was calcium-dependent and was sensitive to inhibition by high magnesium concentrations or tetrodotoxin. Following the destruction of neurons in the striatum by ibotenic acid injections, although the weight of the ipsilateral substantia nigra was reduced, the uptake of [3H]taurine was not altered. In contrast to this, the veratridine-stimulated release was markedly attenuated, implying that the destruction of striatal neurons causes the loss of sites in the substantia nigra from which exogenous taurine is released. These results add further support to previous suggestions that taurine might act as a neurotransmitter or neuromodulator in the striatonigral pathway.