Technical standards for medical devices. Assisted circulation devices

The steep rise in the clinical use of high technology biomedical devices and materials, involving multidisciplinary competencies, points out the problem of mutual standards defining, first of all, functional characteristic and tests able to characterise and qualify devices, materials and minimal safety requirements both for patients and operators. Standards defined by consent of the parties or by law are used to this aim. Fast technical development in specific sectors produces besides lack of rules, which must be quickly filled up. The aim of this paper is both the presentation of the approach to problems related to technical standards for biomedical devices and the presentation of the set up of a technical standard for mechanical heart assist devices.

[Familial periodic ataxia with myokymia sensitive to acetazolamide: a family case]

INTRODUCTION

Acetazolamide responsive hereditary paroxysmal cerebellar ataxia with myokymia is a type of autosomal dominant cerebellar ataxia which locus was found to be linked to the short arm of chromosome 12 and the etiology is unknown.

CLINICAL CASE

A 12 years-old man who suffered from childhood daily episodes of sudden attacks sport induced with giddiness, ataxia and dysarthria for minutes. The familial history shows the same clinical findings in three generations. Intercritical general neurologic evaluation is otherwise normal. The following tests were performed with normal results: Biochemistry, electroencephalogram, cerebral magnetic resonance imaging. The electromyography showed myokymic discharges. The patient's symptoms improve on treatment with acetazolamide immediately.

CONCLUSIONS

Acetazolamide responsive hereditary paroxysmal cerebellar ataxia with myokymia needs to think on it to be diagnosed. No typical complementary test (electromyography exception) induces to base diagnosis in the clinical findings, the familial history and the fast clinical improvement after starting treatment with acetazolamide.

GLP-1 (7-36) amide: effects on glucose transport and metabolism in rat adipose tissue

In rat adipocytes, GLP-1 (7-36) amide induced an increment in 2-deoxy-glucose uptake, which was additive to that of insulin. Furthermore, in rat fat, GLP-1 (7-36) amide provoked a rise in glycogen synthesis, glucose oxidation and utilization and lipogenesis, the increments being lower than those obtained with insulin. These data support the idea that GLP-1 exerts insulin-like effects on glucose metabolism in rat adipose tissue, as it does in rat hepatocytes and skeletal muscle, although with a lower potency than that of insulin.

Preserved GLP-I effects on glycogen synthase a activity and glucose metabolism in isolated hepatocytes and skeletal muscle from diabetic rats

To search if biological effects of GLP-I on glucose metabolism in extrapancreatic tissue are present in diabetic states, we have studied the action of GLP-I and insulin on glycogen-enzyme activity, glycogen synthesis, and glucose metabolism in isolated hepatocytes and soleus muscle from adult streptozotocin (STZ)- and neonatal STZ-treated diabetic rats. This work confirms the previously reported insulin-like effects of GLP-I on glucose metabolism in both muscle and liver tissue from normal rats (control). The present study extends those observations to the muscle and liver tissue of diabetic animals. In both muscle and liver tissue, the metabolism of D-glucose, in the absence of added peptides, was more severely affected in adult STZ (IDDM model) than in neonatal STZ (nSTZ; NIDDM model) rats, and the magnitude of hormonal effect on metabolic variables was lower in diabetic rats than in control rats, as a rule. Nevertheless, in liver and muscle tissue of diabetic rats, GLP-I was able to increase glycogen synthase activity, augment the net rate of D-[U-14C]glucose incorporation into glycogen, and increase D-[5-3H]glucose utilization, D-[U-14C]glucose oxidation, and lactate production. In conclusion, GLP-I exerts insulin-like effects on D-glucose metabolism in both muscle and liver tissue in IDDM or NIDDM animal models, and present observations reinforce the view that GLP-I may represent a most promising tool in the treatment of diabetic patients.

Exendin-4 agonist and exendin(9-39)amide antagonist of the GLP-1(7-36)amide effects in liver and muscle

The GLP-1 structurally related peptides exendin-4 and exendin(9-39)amide were found to act, in rat liver and skeletal muscle, as agonist and antagonist, respectively, of the GLP-1(7-36)amide effects on glucose metabolism. Thus, like GLP-1(7-36)amide, exendin-4 increased glycogen synthase a activity and glucose incorporation into glycogen in both tissues and also stimulated exogenous D-glucose utilization and oxidation in muscle. These effects of GLP-1(7-36)amide and exendin-4 were inhibited by exendin(9-39)amide. Our findings provide further support to the proposed use of GLP-1, or exendin-4, as a tool in the treatment of diabetes mellitus. Thus, in addition to the well-known insulinotropic action of the peptides, they act both in liver and in muscle in a manner most suitable for restoration of glucose homeostasis, with emphasis on their positive effects upon glycogen synthesis in the two tissues and on the stimulation of exogenous glucose catabolism in muscle.

Neonatal outcome and obstetric complications in women with gestational diabetes: effects of maternal body mass index

OBJECTIVE

To evaluate in a selected population the clinical characteristics (time of diagnosis, different treatment, metabolic parameters, etc.) of gestational diabetes in relation to prepregnancy body mass index (BMI) and the influence of BMI on neonatal outcome.

DESIGN

This study was retrospectively led using a computerized data system for all deliveries that occurred at the Departments of Obstetrics and Gynecology of the University of Pisa (Italy) from 1 January 1987 to 31 December 1992.

SUBJECTS

93 women with GDM and 110 control subjects divided into three groups according to their pre-pregnancy BMI: normal weight (Nw), overweight (Ow) and obese (Ob).

MEASUREMENTS

Time of diagnosis, mode of treatment and metabolic control of GDM; time and mode of delivery, neonatal outcome (macrosomia, respiratory distress syndrome, hyperbilirubinemia, hypoglycemia, polycythemia, hypocalcemia).

RESULTS

GDM was diagnosed earlier in Ow and Ob than in Nw (p < 0.01) and insulin treatment was used in 86% of Ob-GDM, 91% of Ow-GDM and in 77% of Nw-GDM women (p < 0.001). Preterm deliveries and cesarean sections resulted significantly increased in all BMI categories of GDM patients with respect to matched normal controls. Prevalence of neonatal macrosomia was higher in GDM patients (44.6%) compared with normal controls (15.4%) and correlated (p > 0.01) with prepregnancy BMI in both groups. The body weight increase during pregnancy was not associated with neonatal macrosomia.

CONCLUSIONS

The degree of overweight is associated with an earlier diagnosis of GDM; prepregnancy BMI is more predictive of macrosomia than weight gain, both in control and GDM women; GDM seems to play the most important role in increasing the possibility of the occurrence of macrosomia.

Cells retrovirally transfected with fibroblast growth factor-2 isoforms exhibit altered adenylate cyclase activity and G-protein functionality

Basic fibroblast growth factor (FGF-2) is synthesized as different molecular mass isoforms all lacking the signal-peptide sequence. The high molecular-mass isoforms (21-24 kDa) possess a signal sequence directing their nuclear translocation. The role of each isoform is still poorly understood, however, modifications in intracellular signalling pathways could explain some effects of these peptides. In order to evaluate the role of FGF-2 isoforms on the adenylate cyclase (AC) signalling pathway, we retrovirally infected a rat pancreatic cell line (AR4-2J) with point-mutated FGF-2 cDNAs, allowing the expression of the 18 (A5 cells) or 22.5 kDa isoform (A3 cells) at a low level. In membrane preparations of A3 cells, unscheduled expression of the 22.5 kDa FGF-2 isoform induced a 2-fold decrease in both basal and forskolin-stimulated AC activity. Studies carried out on intact cells also showed decreased accumulation of cAMP in A3 cells in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Both FGF-2 peptides also induced functional modifications of G-proteins without affecting their levels. The 22.5 kDa peptide led to enhanced ADP-ribosylation of both alpha(s)-subunits in vitro, whereas the expression of the low molecular-mass 18 kDa peptide resulted in a 2-fold increase in alpha12 and alpha0 ADP-ribosylations. Furthermore, control CAT cells (AR4-2J cells transfected with the retrovirus containing the chloramphenicol acetyltransferase gene) and A5 cells were growth-inhibited by 8-Br-cAMP, in contrast to A3 cells. These data provide evidence that the expression of FGF-2 peptides could play a role in cell functions by modifying the AC signalling pathway. FGF-2 peptides are able to modulate both AC activity and the regulatory G-proteins. Finally FGF-2 expression may interfere with cAMP-regulated cell proliferation.

Expression of two FGF-2 isoforms in pancreatic acinar cells (AR4-2J). Intracellular localization and role in the regulation of the extracellular matrix biosynthesis

Fibroblast growth factor (FGF-2) is a multifunctional growth factor. In cells producing this factor, FGF-2 is synthesized as different molecular weight isoforms lacking the signal peptide sequence for secretion. All forms are highly concentrated in cells. The presence of a nuclearization signal sequence in some isoforms suggests the involvement of these isoforms in cell functions bypassing the cell surface receptors. Our aims were to better define the intracellular localizations of the FGF-2 isoforms by immunocytochemistry and confocal microscopy and to analyze whether these isoforms were involved in the expression of extracellular matrix (ECM) components. We chose the pancreatic acinar cell line AR4-2J since it does not synthesize FGF-2. These cells were retrovirally transfected by point-mutated FGF-2 cDNAs. The cell lines obtained produced either the 18 kDa form (A5 cells) or the 22.5 kDa form (A3 cells). In A5 cells, the 18 kDa form was found in the cytoplasm, on the cell surface reflecting its secretion, and in the nucleoli. Parental AR4-2J cells treated with exogenous FGF-2 exhibited identical localizations, suggesting that in A5 cells the 18 kDa form followed the same translocation pathways than the exogenous FGF-2. By contrast, in A3 cells the 22.5 kDa form was predominantly localized in the nucleoplasm but was undetectable on the cell surface, suggesting its direct translocation to the nucleus. Northern and Western blot analysis showed that cells expressing the high molecular weight form exhibited a decrease of laminin B1 protein level and mRNA stability. In contrast, collagen IV and fibronectin expressions were unmodified either in FGF-2-transfected cells or in parental cells treated by exogenous FGF-2. Thus, these data indicate that: 1) 18 and 22.5 kDa FGF-2 are preferentially localized in different nuclear compartments and 2) the high molecular weight form plays a role on the expression of some ECM components.

Differential regulation of fibroblast growth factor (FGF) receptor-1 mRNA and protein by two molecular forms of basic FGF. Modulation of FGFR-1 mRNA stability

To evaluate possible functional differences between basic fibroblast growth factor (FGF) 2 isoforms we analyzed the effects of the 18-kDa FGF-2 which mainly localizes in the cytosol and that of the nuclear-targeted 22.5-kDa form on FGF receptors (FGFR) expression. These peptides were expressed at low amounts through a retroviral-infection system. Point mutated FGF-2 cDNAs under the control of the beta-actin promoter were used to infect a pancreatic cell line (AR4 2J) which does not produce FGF-2. Saturation and competition binding studies with 125I-FGF-2 revealed a 3-fold increase in both high and low affinity receptors in cells expressing the 22.5-kDa form and a 2-fold increase only in the high affinity receptors in cells producing the 18-kDa form. Kd values and molecular weights of the high affinity receptors were unaffected. Increasing cell densities or cell treatment with exogenous FGF-2 resulted in FGFR down-regulation as in control cells. Neutralizing anti-FGF-2 antibodies and suramin did not affect receptor density in control and in cells producing the 22.5-kDa form but further increased by 60 and 80%, respectively, the receptor level in cells synthesizing the 18-kDa form. These data suggest the involvement of the intracellular stored FGF-2 in FGFR up-regulation. Although all cells expressed FGFR-1, -2, and -3 mRNA only the FGFR-1 transcript was found increased, 6-fold in 22.5-kDa expressing cells and 3-fold in cell producing the shortest secreted isoform. The increase in FGFR-1 mRNA levels in the 22.5-kDa expressing cells was due to enhanced stability of the transcript. Confocal microscopy detected the presence of FGFR-1 at the cell surface whereas secretory isoforms of the receptor were not observed. Reverse transcriptase-polymerase chain reaction did not reveal significant differences in the expression of FGFR-1 variants. In the 22.5-kDa expressing cells exogenous FGF-2 evoked a stronger translocation of the calcium-phospholipid-dependent PKC. These results indicate that the transfected FGF-2 isoforms up-regulated FGFR-1 mRNA and protein. The 22.5-kDa form acted by increasing FGFR-1 mRNA stability enhancing cell responses to exogenous FGF-2.

Inositolphosphoglycans and diacyglycerol are possible mediators in the glycogenic effect of GLP-1(7-36)amide in BC3H-1 myocytes

A potent glycogenic effect of GLP-1(7-36)amide has been found in rat hepatocytes and skeletal muscle, and specific receptors for this peptide, which do not seem to be associated with the adenylate cyclase-cAMP system, have been detected in these tissue membranes. On the other hand, inositolphosphoglycan molecules (IPGs) have been implicated as second messengers of the action of insulin. In this work, we have found, in differentiated BC3H-1 myocytes, specific binding of [125I]GLP-1(7-36)amide, and a stimulatory effect of the peptide on glycogen synthesis, confirming the findings in rat skeletal muscle. Also, GLP-1(7-36)amide modulates the cell content of radiolabelled glycosylphosphatidylinositols (GPIs) and increases the production of diacylglycerol (DAG), in the same manner as insulin acts, indicating hydrolysis of GPIs and an immediate and short-lived generation of IPGs. Thus, IPGs and DAG could be mediators in the glycogenic action of GLP-1(7-36)amide in skeletal muscle.

Inositolphosphoglycans are possible mediators of the glucagon-like peptide 1 (7-36)amide action in the liver

A potent glycogenic effect for GLP-1(7-36)amide has been found in rat hepatocytes and skeletal muscle, and the specific receptors detected for GLP-1(7-36)amide in these tissue membranes do not seem to be associated to adenylate cyclase. On the other hand, inositolphosphoglycan molecules (IPGs) have been implicated as second messengers in the action of insulin. In a human hepatoma cell line (HEP G-2), we have observed the presence of [125I]GLP-1(7-36)amide specific binding, and a stimulatory effect of the peptide upon glycogen synthesis, confirming the findings in isolated rat hepatocytes. Also, GLP-1(7-36)amide modulates the cell content of radiolabelled glycosylphosphatidylinositols (GPIs), in the same manner as insulin, indicating hydrolysis of GPIs and an immediate and short-lived generation of IPGs. Thus, IPGs could be mediators in the GLP-1(7-36)amide glycogenic action in the liver.

Physiological effect of glucagon in human isolated adipocytes

In human isolated adipocytes, glucagon induces a dose dependent increment of the glycerol release, which is already observed at physiological concentrations of the hormone. Furthermore, glucagon at 10(-8) M, significantly stimulates the adenylate cyclase activity in both non-solubilized and solubilized fat plasma membranes, and at already 10(-11) M, a significant increment of the adipocyte cAMP content is observed. These data support previous in vivo positive results indicating that glucagon plays a role in human fat metabolism.

Glucagon-like peptide-1 binding to rat hepatic membranes

We have found [125I]glucagon-like peptide (GLP)-1(7-36)amide specific binding activity in rat liver and isolated hepatocyte plasma membranes, with an M(r) of approximately 63,000, estimated by cross-linking and SDS-PAGE. The specific binding was time- and membrane protein concentration-dependent, and equally displaced by unlabelled GLP-1(7-36)amide and by GLP-1(1-36)amide, achieving its ID50 at 3 x 10(-9) M of the peptides. GLP-1(7-36)amide did not modify the basal or the glucagon (10(-8) M)-stimulated adenylate cyclase in the hepatocyte plasma membranes. These data, together with our previous findings of a potent glycogenic effect of GLP-1(7-36)amide in isolated rat hepatocytes, led us to postulate that the insulin-like effects of this peptide on glucose liver metabolism could be mediated by a type of receptor probably different from that described for GLP-1 in pancreatic B-cells or, alternatively, by the same receptor which, in this tissue as well as in muscle, uses a different transduction system.

Glucagon-like peptide-1 binding to rat skeletal muscle

We have found [125I]glucagon-like peptide-1(7-36)-amide-specific binding activity in rat skeletal muscle plasma membranes, with an estimated M(r) of 63,000 by cross-linking and SDS-PAGE. The specific binding was time and membrane protein concentration dependent, and displaceable by unlabeled GLP-1(7-36)-amide with an ID50 of 3 x 10(-9) M of the peptide; GLP-1(1-36)-amide also competed, whereas glucagon and insulin did not. GLP-1(7-36)-amide did not modify the basal adenylate cyclase activity in skeletal muscle plasma membranes. These data, together with our previous finding of a potent glycogenic effect of GLP-1(7-36)-amide in rat soleus muscle, and also in isolated hepatocytes, which was not accompanied by a rise in the cell cyclic AMP content, lead use to believe that the insulin-like effects of this peptide on glucose metabolism in the muscle could be mediated by a type of receptor somehow different to that described for GLP-1 in pancreatic B cells, where GLP-1 action is mediated by the cyclic AMP-adenylate cyclase system.

Potent glycogenic effect of GLP-1(7-36)amide in rat skeletal muscle

GLP-1(7-36)amide is an intestinal post-translational proglucagon product released mainly after carbohydrate ingestion, the glucose dependent insulinotropic and antidiabetogenic actions of which have been documented. In this work, by exploring whether GLP-1(7-36)amide has any effect on the glucose metabolism of the muscle, we have observed that this peptide, at physiological concentrations, exerts in this tissue an increment of the D-[U-14C]glucose incorporated into glycogen, which is accompanied by an increase in the glycogen synthase a activity; also, it stimulates both glucose oxidation and lactate formation. These data indicate that the skeletal muscle is one of the target tissues for GLP-1(7-36)amide, where its insulin-like effect explains, at least in part, its plasma glucose lowering action; thus, GLP-1(7-36)amide may well be implicated in the physiological control of glucose homeostasis after meals, not only by acting as an incretin, but also by directly promoting glucose disposal.

Glucagon-like peptide 1: a potent glycogenic hormone

GLP-1(7-36)amide is an insulinotropic peptide derived from the intestinal post-translational proglucagon process, the release of which is increased mainly after a carbohydrate meal; also, its anti-diabetogenic effect in normal and diabetic states has been reported. In this study, GLP-1(7-36)amide stimulates the formation of glycogen from glucose in isolated rat hepatocytes, such a glycogenic effect being achieved with physiological concentrations of the peptide. The GLP-1(7-36)amide-induced glycogenesis is abolished by glucagon, and it is accompanied by stimulation of the glycogen synthase alpha activity and by a decrease in the basal and glucagon-stimulated cyclic AMP content. These findings could explain, at least in part, the GLP-1(7-36)amide insulin-independent plasma glucose lowering effect.

Caerulein and gastrin(2-17 ds) regulate differently synthesis of secretory enzymes, mRNA levels and cell proliferation in pancreatic acinar cells (AR4-2J)

In order to characterize the biological functions coupled to cholecystokinin (CCK) A and B receptors, the effects of gastrin(2-17 ds) and caerulein were compared. An isolated cell model, the pancreatic acinar cell line AR4-2J, was used and the experiments were carried out in serum-free media. Caerulein was found to evoke no mitogenic effects either alone or in the presence of the CCK antagonists L364,718 and CR1409. Gastrin(2-17 ds) increased cell proliferation by 2-fold with an IC50 of 150 pM, corresponding to the occupancy of the CCK B receptors. CR1409, at concentrations that fully occupied CCK B receptors, inhibited the gastrin(2-17 ds) effects. Caerulein enhanced chymotrypsinogen biosynthesis by 100% and the corresponding mRNA level by 75%; amylase biosynthesis and mRNA level were enhanced by 40% only. Half-maximal increases in chymotrypsin activity and mRNA level were recorded in response to caerulein at concentrations of 100 pM and 50 pM respectively. Gastrin(2-17 ds) at 100 nM enhanced chymotrypsinogen biosynthesis by 26% and its mRNA level by 35%; these responses were lower than those evoked by 0.1 nM caerulein. Furthermore, CR1409 completely inhibited caerulein- and gastrin(2-17 ds)-stimulated chymotrypsinogen synthesis, with similar IC50 (4 microM). These results suggest that both peptides induced the synthesis of the secretory enzyme after occupancy of CCK A receptors.

Decreased expression of transforming growth factor alpha during differentiation of human pancreatic cancer cells

The relationship between cell differentiation and transforming growth factor alpha (TGF-alpha) expression in human pancreatic cancer cells was analyzed in Capan 1 cells. These cells differentiate either spontaneously or after butyrate treatment. During differentiation (spontaneous or butyrate induced), TGF-alpha messenger RNA (mRNA) levels decreased, whereas the TGF-beta 1 mRNA levels remained unchanged. TGF-alpha was present in cells as proTGF-alpha, which decreased after butyrate treatment. Secretion of TGF-alpha was not found. Under the two conditions of differentiation, the membrane-bound protein kinase C activity was also reduced. Conversely, long-term phorbol ester treatment increased both membrane-bound protein kinase C activity (260%) and TGF-alpha mRNA level (500%), a not significant increase of TGF-beta 1 mRNA was observed. However, phorbol 12-myristate-13-acetate did not induce TGF-alpha synthesis or secretion. These data suggest that expression of TGF-alpha can be reduced in cancer cells; they also suggest the existence of a relationship between TGF-alpha expression and cell differentiation. In addition, the protein kinase C-induced TGF-alpha mRNA level was not followed by the increase of TGF-alpha biosynthesis, suggesting a translational control. Finally, the expression of TGF-alpha and -beta 1 messengers appears to be differently regulated.

Characterization of trypsinogens 1 and 2 in two human pancreatic adenocarcinoma cell lines; CFPAC-1 and CAPAN-1

Proteins with trypsin-like immunoreactivity (first detected by a specific immunoenzymatic assay) were isolated from CAPAN-1 and CFPAC-1 cell culture-conditioned media by chromatography on an immunoadsorbent prepared with a polyclonal antibody directed against trypsin 1. The adsorbed proteins were devoid of free trypsin activity but trypsin activity was present after enterokinase activation demonstrating that the immunoreactive trypsin present in cell supernatants corresponds to trypsinogens. When characterised by Western blotting using a monoclonal antibody directed against human trypsin 1 two protein bands corresponding to trypsinogen 1 (23 kDa) and trypsinogen 2 (25 kDa) gave a positive reaction. These results demonstrate the presence of trypsinogens 1 and 2 in CAPAN-1 and CFPAC-1 cells and in their culture-conditioned media.

A real-time FFT analyser for monitoring muscle fatigue

The TMS 32010 system for a real-time muscle fatigue monitor is described; it is based on mean frequency shift in the electromyographic signal (EMG). The mean frequency of the EMG is obtained, in real time, from its power spectrum, with a 2 Hz resolution. This is made possible by combining novel hardware and software.

Regulation of amylase and chymotrypsinogen expression by dexamethasone and caerulein in serum-free-cultured pancreatic acinar AR4-2J cells. Influence of glucose

The direct effects of dexamethasone and caerulein on two pancreatic enzymes, amylase and chymotrypsin, were determined in AR4-2J cells cultured under serum-free conditions at two glucose concentrations (1.0 and 4.5 g/l). In the absence of any hormone, the higher glucose concentration resulted in a 1.6-1.8-fold increase in the basal levels of amylase and chymotrypsinogen. Dexamethasone (50 nM) increased the biosynthesis and mRNA levels of both enzymes at both glucose concentrations. However, dexamethasone had a more pronounced effect on amylase biosynthesis (5-fold induction) than on chymotrypsinogen biosynthesis (1.8-fold induction). The parallel increases in mRNA and protein indicated the existence of pre-translational regulation. This is in contrast with what was observed in serum-containing media, where a translational regulation of amylase biosynthesis took place, probably under the control of both glucose and some serum factors. By contrast, caerulein (10 nM) exerted a more specific action on chymotrypsinogen. The increases in chymotrypsinogen mRNA were 2.2- and 2.1-fold, and increases in chymotrypsin activity were 1.6- and 2.9-fold at 1.0 and 4.5 g of glucose/litre respectively. Thus the regulation by caerulein occurred mainly through the enhancement of chymotrypsinogen transcription and/or mRNA stabilization.

Lipid-dependent proliferation of pancreatic cancer cell lines

Capan 1, a human pancreatic cancer cell line, is routinely grown in 10% fetal calf serum (FCS). In order to characterize the factors needed for its proliferation, FCS was replaced by a synthetic serum (Ultroser G). For Capan 1 proliferation we found that Ultroser G was as efficient as FCS. A subfraction of Ultroser G containing insulin, transferrin, and lipids was found to be responsible for that response since a combination of these compounds reproduced the growth observed with 10% FCS. Lipids stimulated cell proliferation even in the absence of other factors. Other human (MIA PaCa 2, AsPC1, Panc 1) or rat (AR4-2J) pancreatic cancer cell lines tested proliferated in the reconstituted medium containing insulin (100 ng/ml), transferrin (100 micrograms/ml), fatty acid-free albumin (1 mg/ml), and bovine serum lipids (0.7%), as in 10% FCS. Furthermore, the growth of nonpancreatic cell lines (HT29, A431, CREF) was not enhanced by lipids. Lipoproteins were found to be involved in the mitogenic response of pancreatic cells to lipids, whereas phosphatidylcholine and fatty acids were either inefficient or inhibitors (MIA PaCa2 and AR4-2J). Alkaline phosphatase and amylase content, differentiation markers for Capan 1 and AR4-2J cells, respectively, were not modified by the reconstituted medium. These data suggest that lipids, insulin, and transferrin are the essential factors for the proliferation of pancreatic cancer cell lines, reproducing the growth effect of 10% FCS. Moreover, in the absence of most of the seric growth factors, pancreatic cells remained differentiated.

Interstitial 15q deletion without a classic Prader-Willi phenotype

We report on a newborn boy with pronounced hypotonia, cryptorchidism, minor facial anomalies, congenital heart defect, neurologic anomaly, deafness, renal anomaly, and bifid uvula. The patient has a de novo proximal interstitial deletion of chromosome 15 reaching to band q14, larger than that usually seen in Prader-Willi and Angelman syndromes.

A flexible FFT algorithm for processing biomedical signals using a personal computer

The aim was to demonstrate the possibility of using personal computer PC-DOS (or generally MS-DOS) for real-time (or quasi real-time) biomedical signal processing by adding a simple A/D conversion card and the mathematical coprocessor XXX87. We have realized an assembly written fast Fourier transform (FFT) routine derived from a radix-4 algorithm, which is autogenerated, i.e. an algorithm modified by another algorithm running off-line according to the number of FFT points. The program is implemented as a subroutine to be called upon by high-level language in different procedures. This approach reduces the computational time, which is particularly useful when many Fourier transforms on different data arrays are required. Reported here are two different applications of the routine as applied to the spectral analysis of Doppler ultrasound velocimetry and surface electromyography.