Neuronal ceroid lipofuscinosis genes, CLN2, CLN3 and CLN5 are spatially and temporally co-expressed in a developing mouse brain.

Neuronal ceroid lipofuscinosis (NCL) diseases consist of a group of genetically inherited neurodegenerative disorders that share common symptoms such as seizures, psychomotor retardation, blindness, and premature death. Although gene defects behind the NCL diseases are well characterized, very little is known how these defects affect normal development of the brain and cause the pathology of the disease. To obtain understanding of the development of the cell types that are mostly affected by defective function of CLN proteins, timing of expression of CLN2, CLN3 and CLN5 genes was investigated in developing mouse brain. The relationship between the expression pattern and the developmental stage of the brain showed that these genes are co-expressed spatially and temporally during brain development. Throughout the development strong expression of the three mRNAs was detected in germinal epithelium and in ventricle regions, hippocampus and cerebellum, all representing regions that are known to be associated with the formation of new neurons. More specifically, RT-PCR studies on developing mouse cortices revealed that the CLN genes were temporally co-expressed in the neural progenitor cells together with known stem cell markers. This suggested that CLN2, CLN3 and CLN5 genes may play an important role in early embryonal neurogenesis.

Utility of cystatin C for renal function in amyotrophic lateral sclerosis.

OBJECTIVES: Creatinine (Cr) as a marker of renal function has limited value in amyotrophic lateral sclerosis (ALS) because patients with ALS have reduced muscle mass. Thus, there is a need for alternative methods of assessing renal function. Cystatin C (CysC), which is unaffected by muscle mass, is potentially an ideal biomarker of nephrotoxicity in ALS; however, its utility requires validation. MATERIAL AND METHODS: One hundred and six subjects were recruited for the study: 76 ALS patients and 30 healthy controls. We compared the Cr-based estimated glomerular filtration rate (eGFR) with the CysC-based eGFR in the ALS patients and healthy controls. The results were further analysed according to the severity of ALS in the patients. RESULTS: The mean Cr-based eGFRs were 257.2 ± 383.1 ml/min/1.73 m(2) in the ALS group and 98.1 ± 34.9 in the control group; however, the mean CysC-based eGFRs were not significantly different between both groups. Thus, the Cr-based eGFR in the ALS group was markedly higher than any of the other values. Although serum CysC levels did not correlate with the severity of ALS according to the ALS Functional Rating Scale-Revised, strong simple correlations were observed between serum Cr levels and the severity of ALS (correlation coefficient = 0.734, P < 0.001). CONCLUSIONS: This study demonstrates the potential usefulness of CysC as a biomarker of renal function in ALS patients. Furthermore, its applicability could be extended to other neuromuscular diseases.

Mutations in the core and NS5A region of hepatitis C virus genotype 1b and correlation with response to pegylated-interferon-alpha 2b and ribavirin combination therapy.

Mutations in two regions of hepatitis C virus (HCV) have been implicated in influencing response to interferon (IFN) therapy. Substitutions in the NS5A region of HCV have been associated with response to IFN therapy, and this region has been known as the IFN sensitivity-determining region (ISDR). The mutations in the core region of HCV have also been reported to predict IFN response. The aim of this study was to investigate whether amino acid substitutions in the core region and ISDR among patients with HCV genotype 1b affect the response to IFN therapy. A total of 213 patients who completed IFN treatment were randomly selected. All patients received pegylated-IFN-alpha 2b once each week, plus oral ribavirin daily for 48 weeks. Of the 213 patients, 117 (54.9%) showed early virologic response (EVR), with HCV-negativity, at 12 weeks. Factors related to EVR on multivariate analysis were non-Gln70 and Leu91 in the core region, and ISDR mutant-type. One hundred and two (47.9%) showed a sustained virologic response (SVR). SVR occurred more frequently in patients without Gln70 (55.4%) than in those with Gln70 (21.3%) (P < 0.0001). SVR was achieved in 43.6% of patients with wild-type ISDR and 62.5% of patients with mutant-type (P = 0.0227). Of the 34 patients who simultaneously had non-Gln70 and mutant-type ISDR, 26 (76.5%) achieved SVR. Factors related to SVR on multivariate analysis were non-Gln70 and ISDR mutant-type. In conclusion, amino acid substitutions in the core region and ISDR were useful for predicting the response to IFN in patients with HCV genotype 1b.

The nuclear DICER-circular RNA complex drives the deregulation of the glioblastoma cell microRNAome.

The assortment of cellular microRNAs ("microRNAome") is a vital readout of cellular homeostasis, but the mechanisms that regulate the microRNAome are poorly understood. The microRNAome of glioblastoma is substantially down-regulated in comparison to the normal brain. Here, we find malfunction of the posttranscriptional maturation of the glioblastoma microRNAome and link it to aberrant nuclear localization of DICER, the major enzymatic complex responsible for microRNA maturation. Analysis of DICER's nuclear interactome reveals the presence of an RNA binding protein, RBM3, and of a circular RNA, circ2082, within the complex. Targeting of this complex by knockdown of circ2082 results in the restoration of cytosolic localization of DICER and widespread derepression of the microRNAome, leading to transcriptome-wide rearrangements that mitigate the tumorigenicity of glioblastoma cells in vitro and in vivo with correlation to favorable outcomes in patients with glioblastoma. These findings uncover the mechanistic foundation of microRNAome deregulation in malignant cells.

Novel SACS mutation in a Belgian family with sacsin-related ataxia.

The authors describe the four patients in the first known Belgian family with autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). A novel homozygous missense mutation, NM_014363.3: c.3491T>A in exon 9, of the SACS gene was identified in the present family, which results in an original amino acid of methionine to lysine substitution at amino acid residue 1164 (p.M1164K). Although the cardinal clinical features, i.e., spastic ataxia with peripheral neuropathy, in our patients were similar to those in Quebec patients, our patients exhibited some atypical clinical features, e.g., teenage-onset and absence of retinal hypermyelination. The present family is from Wallonia, and there could be shared ethnicity with the families of Charlevoix-Saguenay.

Molecular subtypes and differentiation programmes of glioma stem cells as determinants of extracellular vesicle profiles and endothelial cell-stimulating activities.

We have previously uncovered the impact of oncogenic and differentiation processes on extracellular vesicles (EVs) in cancer. This is of interested in the context of glioma stem cells (GSC) that are responsible for recurrent nature of glioblastoma multiforme (GBM), while retaining the potential to undergo differentiation and self renewal.  GSCs reside in vascular niches where they interact with endothelial cells through a number of mediators including bioactive cargo of EVs. GSCs can be classified as proneural (PN) or mesenchymal (MES) subtypes on the basis of their gene expression profiles and distinct biological characteristics. In the present study we investigated how GSC diversity and differentiation programmes influence their EV-mediated communication potentials. Indeed, molecular subtypes of GBMs and GSCs differ with respect to their expression of EV-related genes (vesiculome) and GSCs with PN or MES phenotypes produce EVs with markedly different characteristics, marker profiles, proteomes and endothelial stimulating activities. For example, while EVs of PN GSC are largely devoid of exosomal markers their counterparts from MES GSCs express ample CD9, CD63 and CD81 tetraspanins. In both GSC subtypes serum-induced differentiation results in profound, but distinct changes of cellular phenotypes including the enhanced EV production, reconfiguration of their proteomes and the related functional pathways. Notably, the EV uptake was a function of both subtype and differentiation state of donor cells. Thus, while, EVs produced by differentiated MES GSCs were internalized less efficiently than those from undifferentiated cells they exhibited an increased stimulatory potential for human brain endothelial cells. Such stimulating activity was also observed for EVs derived from differentiated PN GSCs, despite their even weaker uptake by endothelial cells. These findings suggest that the role of EVs as biological mediators and biomarkers in GBM may depend on the molecular subtype and functional state of donor cancer cells, including cancer stem cells. Abbreviations: CryoTEM: cryo-transmission electron microscopy; DIFF: differentiated GSCs; EGF: epidermal growth factor; DUC: differential ultracentrifugation; EV: extracellular vesicle; FGF: fibroblast growth factor; GBM: glioblastoma multiforme; GFAP: glial fibrillary acidic protein; GO: gene ontology; GSC: glioma stem cells; HBEC-5i: human brain endothelial cells; MES: mesenchymal cells; MTS - [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; PMT1: proneural-to-mesenchyman transition cell line 1; PN: proneural cells; TEM: transmission electron microscopy; WB: western blotting.

PBK/TOPK, a proliferating neural progenitor-specific mitogen-activated protein kinase kinase.

We performed genomic subtraction coupled to microarray-based gene expression profiling and identified the PDZ (postsynaptic density-95/Discs large/zona occludens-1)-binding kinase/T-LAK (lymphokine-activated killer T cell) cell originating protein kinase (PBK/TOPK) as a gene highly enriched in neural stem cell cultures. Previous studies have identified PBK/TOPK as a mitogen-activated protein kinase (MAPK) kinase that phosphorylated P38 MAPK but with no known expression or function in the nervous system. First, using a novel, bioinformatics-based approach to assess cross-correlation in large microarray datasets, we generated the hypothesis of a cell-cycle-related role for PBK/TOPK in neural cells. We then demonstrated that both PBK/TOPK and P38 are activated in a cell-cycle-dependent manner in neuronal progenitor cells in vitro, and inhibition of this pathway disrupts progenitor proliferation and self-renewal, a core feature of progenitors. In vivo, PBK/TOPK is expressed in rapidly proliferating cells in the adult subependymal zone (SEZ) and early postnatal cerebellar external granular layer. Using an approach based on transgenically targeted ablation and lineage tracing in mice, we show that PBK/TOPK-positive cells in the SEZ are GFAP negative but arise from GFAP-positive neural stem cells during adult neurogenesis. Furthermore, ablation of the adult stem cell population leads to concomitant loss of PBK/TOPK-positive cells in the SEZ. Together, these studies demonstrate that PBK/TOPK is a marker for transiently amplifying neural progenitors in the SEZ. Additionally, they suggest that PBK/TOPK plays an important role in these progenitors, and further implicates the P38 MAPK pathway in general, as an important regulator of progenitor proliferation and self-renewal.

16q-linked autosomal dominant cerebellar ataxia: a clinical and genetic study.

The autosomal dominant cerebellar ataxias (ADCAs) comprise a genetically and clinically heterogenous group of neurodegenerative disorders. Very recently, a C-to-T single nucleotide substitution in the puratrophin-1 gene was found to be strongly associated with a form of ADCA linked to chromosome 16q22.1 (16q-linked ADCA; OMIM 600223). We found the C-to-T substitution in the puratrophin-1 gene in 20 patients with ataxia (16 heterozygotes and four homozygotes) and four asymptomatic carriers in 9 of 24 families with an unknown type of ADCA. We also found two cases with 16q-linked ADCA among 43 sporadic patients with late-onset cortical cerebellar atrophy (LCCA). The mean age at onset in the 22 patients was 61.8 years, and that of homozygous patients was lower than that of heterozygous ones in one family. Neurological examination revealed that the majority of our patients showed exaggerated deep tendon reflexes in addition to the cardinal symptom of cerebellar ataxia (100%), and 37.5% of them had sensorineural hearing impairment, whereas sensory axonal neuropathy was absent. The frequency of 16q-linked ADCA was about 1/10 of our series of 110 ADCA families, making it the third most frequent ADCA in Japan.

Restitution of ischemic injuries in penumbra of cerebral cortex after temporary ischemia.

We investigated, at both light and ultrastructural levels, the fate of swollen astrocytes and remodeling of neurites connected to disseminated, dying neurons in the ischemic neocortical penumbra. Specimens from left cerebral cortex were cut coronally at the infundibulum and observed by light and electron microscopy. We measured synapses and spines, and the thickness of neuritic trunks in the neuropil on electron microscopy photos. We also determined percent volume of axon terminals and spines by Weibel's point-counting method. Astrocytic swelling gradually subsided from day 4 after the ischemic insult, with increases in cytoplasmic glial fibrils and GFAP-positive astrocytes. Disseminated dying electron-dense neurons were fragmented by invading astrocytic cell processes and accumulated as granular pieces. The number of synapses and spines and total percent volume of axon terminals and spines decreased with an increasing sparsity of synaptic vesicles until day 4. One to 12 weeks after the ischemic insult, these values increased to or exceeded control values, and sprouting and increased synaptic vesicles were seen. Axons that had been attached to the dying neurons appeared to have shifted their connections to the spines and the neurites of the surviving neurons, increasing their thickness. Astrocytic restitution and neuronal remodeling processes started at 4 days continuing until 12 weeks after ischemic insult.

SHP-2-upregulated ZEB1 is important for PDGFRα-driven glioma epithelial-mesenchymal transition and invasion in mice and humans.

Gliomas are highly malignant brain tumors that are highly invasive and resistant to conventional therapy. Receptor tyrosine kinases (RTKs) such as PDGFRα (platelet-derived growth factor receptor-α), which show frequent aberrant activation in gliomas, are associated with a process of epithelial-mesenchymal transition (EMT), a cellular alteration that confers a more invasive and drug-resistant phenotype. Although this phenomenon is well documented in human cancers, the processes by which RTKs including PDGFRα mediate EMT are largely unknown. Here, we report that SHP-2 (encoded by PTPN11) upregulates an EMT inducer, ZEB1, to mediate PDGFRα-driven glioma EMT, invasion and growth in glioma cell lines and patient-derived glioma stem cells (GSCs) using cell culture and orthotopic xenograft models. ZEB1 and activated PDGFRα were coexpressed in invasive regions of mouse glioma xenografts and clinical glioma specimens. Glioma patients with high levels of both phospho-PDGFRα (p-PDGFRα) and ZEB1 had significantly shorter overall survival compared with those with low expression of p-PDGFRα and ZEB1. Knockdown of ZEB1 inhibited PDGFA/PDGFRα-stimulated glioma EMT, tumor growth and invasion in glioma cell lines and patient-derived GSCs. PDGFRα mutant deficient of SHP2 binding (PDGFRα-F720) or phosphoinositide 3-kinase (PI3K) binding (PDGFRα-F731/42), knockdown of SHP2 or treatments of pharmacological inhibitor for PDGFRα-signaling effectors attenuated PDGFA/PDGFRα-stimulated ZEB1 expression, cell migration and GSC proliferation. Importantly, SHP-2 acts together with PI3K/AKT to regulate a ZEB1-miR-200 feedback loop in PDGFRα-driven gliomas. Taken together, our findings uncover a new pathway in which ZEB1 functions as a key regulator for PDGFRα-driven glioma EMT, invasiveness and growth, suggesting that ZEB1 is a promising therapeutic target for treating gliomas with high PDGFRα activation.

The LIM-only transcription factor LMO2 determines tumorigenic and angiogenic traits in glioma stem cells.

Glioblastomas (GBMs) maintain their cellular heterogeneity with glioma stem cells (GSCs) producing a variety of tumor cell types. Here we interrogated the oncogenic roles of Lim domain only 2 (LMO2) in GBM and GSCs in mice and human. High expression of LMO2 was found in human patient-derived GSCs compared with the differentiated progeny cells. LMO2 is required for GSC proliferation both in vitro and in vivo, as shRNA-mediated LMO2 silencing attenuated tumor growth derived from human GSCs. Further, LMO2 is sufficient to induce stem cell characteristics (stemness) in mouse premalignant astrocytes, as forced LMO2 expression facilitated in vitro and in vivo growth of astrocytes derived from Ink4a/Arf null mice and acquisition of GSC phenotypes. A subset of mouse and human GSCs converted into vascular endothelial-like tumor cells both in vitro and in vivo, which phenotype was attenuated by LMO2 silencing and promoted by LMO2 overexpression. Mechanistically, the action of LMO2 for induction of glioma stemness is mediated by transcriptional regulation of Jagged1 resulting in activation of the Notch pathway, whereas LMO2 directly occupies the promoter regions of the VE-cadherin gene for a gain of endothelial cellular phenotype. Subsequently, selective ablation of human GSC-derived VE-cadherin-expressing cells attenuated vascular formation in mouse intracranial tumors, thereby significantly prolonging mouse survival. Clinically, LMO2 expression was elevated in GBM tissues and inversely correlated with prognosis of GBM patients. Taken together, our findings describe novel dual roles of LMO2 to induce tumorigenesis and angiogenesis, and provide potential therapeutic targets in GBMs.

Survivin as a therapeutic target in Sonic hedgehog-driven medulloblastoma.

Medulloblastoma (MB) is a highly malignant brain tumor that occurs primarily in children. Although surgery, radiation and high-dose chemotherapy have led to increased survival, many MB patients still die from their disease, and patients who survive suffer severe long-term side effects as a consequence of treatment. Thus, more effective and less toxic therapies for MB are critically important. Development of such therapies depends in part on identification of genes that are necessary for growth and survival of tumor cells. Survivin is an inhibitor of apoptosis protein that regulates cell cycle progression and resistance to apoptosis, is frequently expressed in human MB and when expressed at high levels predicts poor clinical outcome. Therefore, we hypothesized that Survivin may have a critical role in growth and survival of MB cells and that targeting it may enhance MB therapy. Here we show that Survivin is overexpressed in tumors from patched (Ptch) mutant mice, a model of Sonic hedgehog (SHH)-driven MB. Genetic deletion of survivin in Ptch mutant tumor cells significantly inhibits proliferation and causes cell cycle arrest. Treatment with small-molecule antagonists of Survivin impairs proliferation and survival of both murine and human MB cells. Finally, Survivin antagonists impede growth of MB cells in vivo. These studies highlight the importance of Survivin in SHH-driven MB, and suggest that it may represent a novel therapeutic target in patients with this disease.

Behavioral recovery in 6-hydroxydopamine-lesioned rats by cotransduction of striatum with tyrosine hydroxylase and aromatic L-amino acid decarboxylase genes using two separate adeno-associated virus vectors.

Parkinson's disease (PD) is characterized by the progressive loss of the dopaminergic neurons in the substantia nigra and a severe decrease in dopamine in the striatum. A promising approach to the gene therapy of PD is intrastriatal expression of enzymes in the biosynthetic pathway for dopamine. Tyrosine hydroxylase (TH) catalyzes the synthesis of L-dopa, which must be converted to dopamine by aromatic L-amino acid decarboxylase (AADC). Since the endogenous AADC activity in the striatum is considered to be low, coexpression of both TH and AADC in the same striatal cells would increase the dopamine production and thereby augment the therapeutic effects. In the present study, the TH gene and also the AADC gene were simultaneously transduced into rat striatal cells, using two separate adeno-associated virus (AAV) vectors, AAV-TH and AAV-AADC. Immunostaining showed that TH and AADC were coexpressed efficiently in the same striatal cells in vitro and in vivo. Moreover, cotransduction with these two AAV vectors resulted in more effective dopamine production and more remarkable behavioral recovery in 6-hydroxydopamine (6-OHDA)-lesioned rats, compared with rats receiving AAV-TH alone (p < 0.01). These findings suggest an alternative strategy for gene therapy of PD and indicate that the simultaneous transduction with two AAV vectors can extend their utility for potential gene therapy applications.

Triple transduction with adeno-associated virus vectors expressing tyrosine hydroxylase, aromatic-L-amino-acid decarboxylase, and GTP cyclohydrolase I for gene therapy of Parkinson's disease.

Parkinson's disease (PD), a neurological disease suited to gene therapy, is biochemically characterized by a severe decrease in the dopamine content of the striatum. One current strategy for gene therapy of PD involves local production of dopamine in the striatum achieved by inducing the expression of enzymes involved in the biosynthetic pathway for dopamine. We previously showed that the coexpression of tyrosine hydroxylase (TH) and aromatic-L-amino-acid decarboxylase (AADC), using two separate adeno-associated virus (AAV) vectors, resulted in more effective dopamine production and more remarkable behavioral recovery in 6-hydroxydopamine-lesioned parkinsonian rats, compared with the expression of TH alone. Not only levels of TH and AADC but also levels of tetrahydrobiopterin (BH4), a cofactor of TH, and GTP cyclohydrolase I (GCH), a rate-limiting enzymes for BH4 biosynthesis, are reduced in parkinsonian striatum. In the present study, we investigated whether transduction with separate AAV vectors expressing TH, AADC, and GCH was effective for gene therapy of PD. In vitro experiments showed that triple transduction with AAV-TH, AAV-AADC, and AAV-GCH resulted in greater dopamine production than double transduction with AAV-TH and AAV-AADC in 293 cells. Furthermore, triple transduction enhanced BH4 and dopamine production in denervated striatum of parkinsonian rats and improved the rotational behavior of the rats more efficiently than did double transduction. Behavioral recovery persisted for at least 12 months after stereotaxic intrastriatal injection. These results suggest that GCH, in addition to TH and AADC, is important for effective gene therapy of PD.

Atrophic cell processes of large motor neurons in the anterior horn in amyotrophic lateral sclerosis: observation with silver impregnation method.

Investigation of silver-stained lumbar anterior horns in four autopsied cases of sporadic amyotrophic lateral sclerosis (ALS) revealed frequent extremely small cell processes originating from large motor neurons. Their perikarya were usually smaller in size than those of normal-looking ones and almost invariably had central chromatolysis-like changes, suggesting an intimate pathomorphological relationship between the perikarya and their processes. Although it was difficult to determine whether these small processes were atrophic dendrites or shrunken axons, some were recognized as dendrites from their multiple branchings and some were identified as axons from their tapering configuration followed by widening of the distal portion. Aggregates of lipofuscin were almost always present in the perikaryal portion from which an atrophic process arose. In addition, the somewhat argentophilic slender cytoplasm which in normal neurons separates lipofuscin from the cell surface and merges with the proximal part of a process, was prominently attenuated. The small processes were more frequently observed in cases with many spheroids and chromatolytic neurons. The change in the proximal portion of the processes may implicate some disturbance of functional connection between the soma and the cell processes in ALS.

Fine structural observations of neurofilamentous changes in amyotrophic lateral sclerosis.

Twenty-two of 32 sporadic cases of amyotrophic lateral sclerosis had argyrophilic spheroids, 20 micrometers or larger, in the anterior horns of the spinal cords. The fine structure of these spherical bodies was characterized by interwoven, small bundles of 10 nm neurofilaments. Scattered mitochondria, vesicles and fragments of smooth endoplasmic reticulum were commonly found among the bundles of neurofilaments. The spheroids were present not only in the myelinated axons, but also in the perikarya of the anterior horn cells. In anterior horn neurons occasional fragments of rough endoplasmic reticulum, lipofuscin and even nuclei were found among the neurofilaments, in addition to the other components. Rarely, some filamentous accumulations contained unusual features such as paracrystalline arrays, polyglucosan bodies and honeycomb-like structures. Linear densities, associated with ribosome-like particles, were found scattered within focal collections of randomly arranged neurofilaments in some perikarya of two cases. Occasional mitochondria with regularly arranged short protrusions on the outer membrane were observed in the myelinated axons in one case.

Fine structural study of neurofibrillary changes in a family with amyotrophic lateral sclerosis.

Lewy body-like hyaline inclusions in the soma and swollen, cord-like cell processes are characteristic alterations of the anterior horn cells in familial amyotrophic lateral sclerosis (ALS) with posterior column and spinocerebellar tract involvement. A fine structural analysis of these two structures has been performed in two brothers from a family ("C" family) previously described by Kurland and Mulder in 1955. The perikaryal hyaline inclusions consisted of accumulations of randomly oriented neurofilaments interspersed with thick linear densities associated with granular material. Some of the accumulations showed a central condensation. Cord-like, swollen neuronal processes were composed, for the most part, of numerous neurofilaments arranged parallel to the long axes. Dense structures were sometimes observed within the large bundles of filaments. They were composed of ill-defined dense, granular and fibrillar material associated with scattered vesicles and mitochondria. These dense areas were sometimes surrounded by various amounts of fine filaments, approximately 5 nm in diameter.

Role of secretin in basal and fat-stimulated pancreatic secretion in conscious rats.

The role of endogenous secretin in basal and fat-stimulated pancreatic exocrine secretion was investigated in conscious rats. Rats were prepared with chronic fistulas draining bile and pancreatic juice, which was collected and returned to the duodenum at all times. Six days postoperative rats were fasted overnight, and pancreatic protein and fluid secretion were monitored for 3 h under basal conditions (0.15 M NaCl, intraduodenally) and during 2 h of intraduodenal infusion of a 20% triglyceride emulsion (Liposyn). Solutions were infused at 4.6 ml/h. Rats received a single bolus injection of 0.1 ml antisecretin serum or normal rabbit serum starting in the second hour of the basal period, and the effect on basal and fat-stimulated pancreatic protein and fluid secretion was determined. Antisecretin serum significantly inhibited basal interdigestive pancreatic protein and fluid secretion by 43% and 36%, respectively. Infusion of 20% fat emulsion stimulated a 2.1-fold increase in pancreatic protein and fluid secretion. The stimulation of both protein and fluid secretion was significantly inhibited by 60% by antisecretin serum. Plasma secretin after 2 h of fat infusion was 17.7 +/- 1.8 pM and was greatly reduced by the presence of secretin antiserum. The results support the hypothesis that secretin released by fatty acids is an important mediator of the pancreatic protein and fluid secretory response to dietary fat in the rat.

Clinical comparison of Alzheimer's disease in pedigrees with the codon 717 Val-->Ile mutation in the amyloid precursor protein gene.

Alzheimer's disease (AD) is the most common cause of dementia (32). Although the majority of cases of AD are sporadic, the most consistent risk factor detected in several epidemiological studies has been a positive family history of the disease (14,21). In addition, many large pedigrees have been described in which AD appears to be inherited as an autosomal dominant disorder. In one such pedigree (F23) a point mutation within the beta-amyloid precursor protein (APP) gene at codon 717 was identified and hypothesized to be pathogenic (10). The mutation results in a valine to isoleucine change in APP (APP717 Val-->Ile). Subsequent screening has revealed four other pedigrees, detailed in this study, in which this mutation co-segregates with AD (13,26,37). In addition, one other pedigree (Tor3) with this mutation has been described (15) and detailed clinical, neuropsychological, and neuropathological data are reported. Tor3 is discussed below in comparison to the findings in the families in this study. The five families we report with the mutation were identified in Britain (1 family), the United States (1 family), and Japan (3 families). The mutation has not been reported in the general population of any of these countries (3,13,26,33). On this basis alone it seems this mutation is pathogenic. Other APP codon 717 mutations have been identified which co-segregate with the disease (4,25). Also, a double mutation in APP at codons 670/671 has been shown to cosegregate with the disease in two large Swedish pedigrees (22). In all cases, there is complete co-segregation of the APP mutation with early onset AD, providing overwhelming statistical evidence that these mutations are pathogenic. We present the clinical features and limited neuropathology of AD in these families with the APP 717 Val-->Ile mutation.

Plasma cholecystokinin and pancreatic polypeptide responses after ingestion of a liquid test meal rich in medium-chain fatty acids in patients with chronic pancreatitis.

Plasma cholecystokinin (CCK) and human pancreatic polypeptide (hPP) responses after ingestion of a liquid test meal rich in medium-chain fatty acids (MCFA) were studied in patients with chronic pancreatitis with or without diabetes mellitus (DM). Integrated response of plasma CCK was significantly lower in patients with chronic pancreatitis and DM than in the two other groups. There was no statistically significant difference between the healthy control subjects and the patients with chronic pancreatitis without DM in the integrated responses of hPP and plasma CCK. These results indicate that diabetic patients with a greatly destroyed pancreas do not release as much CCK as do nondiabetic patients with a mildly impaired pancreas. An MCFA meal is therefore considered safe in patients with a mildly impaired pancreas. For diabetic patients, however, care should be taken not to exacerbate the DM.