Cerebral microembolism during transcatheter closure of patent foramen ovale

BACKGROUND

Although transcatheter closure of patent foramen ovale (PFO) and atrial septal defect (ASD) has become a commonly performed intervention, the incidence of cerebral embolism with or without neurological deficits during such procedures has not been studied.

METHODS

We monitored the middle cerebral artery in two different depths (48 mm and 53 mm) by continuous transcranial Doppler ultrasound during transcatheter PFO closure in 35 consecutive patients (F/M 20/15, mean age 47 +/- 11 years) and during ASD closure in 8 patients (F/M 7/1, mean age 45 +/- 5 years). All automatically detected high intensity transient signals (HITS) were manually reviewed to eliminate artifacts.

RESULTS

HITS were detected in 33 of 35 patients (96%) with a median rate of 8 (interquartile range 4-19, range 2-29) HITS. The highest rates were observed when the septum was crossed with the guide wire (median 2; IQR 0-12; range 0-25) and when the left atrial disc was deployed (median 2; IQR 1-4; range 0-13). Despite this high rate of cerebral microembolism no clinically apparent neurological or neuropsychological deficit was observed.

CONCLUSIONS

Silent cerebral embolism frequently occurs during transcatheter PFO and ASD closure. The peak of HITS at the time of crossing the septum with the guide wire may support the hypothesis that cerebral emboli in patients with PFO may originate from the septum itself. This may represent an alternative mechanism to the generally assumed paradoxical embolism.

Triflusal vs aspirin for prevention of cerebral infarction

BACKGROUND

Triflusal is an antiplatelet agent that has shown clinical advantages when compared with aspirin in the secondary prevention of vascular events. TAPIRSS (Triflusal versus Aspirin for Prevention of Infarction: a Randomized Stroke Study) explored the efficacy and safety of triflusal in the secondary prevention of stroke in a Latin American homogeneous population with the ultimate aim of preparing for a larger trial in the same setting.

METHODS

A double-blind, multicenter, randomized, pilot trial was conducted in Buenos Aires, Argentina, from October 1996 to November 1999. The study sample was 431 patients, randomized to receive aspirin 325 mg daily or triflusal 600 mg daily for a mean of 586 days. All patients had experienced either an ischemic stroke or TIA within 6 months from enrollment. Data from 429 patients were analyzed.

RESULTS

No differences were observed in the primary endpoint that combined the incidence of vascular death, cerebral ischemic infarction, nonfatal myocardial infarction, or major hemorrhage (aspirin 13.9%, triflusal 12.7%; odds ratio [OR] 1.11, 95% CI 0.64 to 1.94) or in the individual analysis of each component of the primary endpoint. In a post hoc analysis, the overall incidence of major and minor hemorrhagic events was significantly lower in triflusal-treated patients (aspirin 8.3%, triflusal 2.8%; OR 3.13, 95% CI 1.22 to 8.06).

CONCLUSIONS

This pilot trial has not found differences between triflusal and aspirin in the prevention of vascular complications after TIA or ischemic stroke, although given the wide CI, potentially important group differences could not be ruled out. Triflusal may be associated with a lower risk of hemorrhagic complications. A larger, prospective clinical trial is necessary to verify these results.

Interventions for treating hallux valgus (abductovalgus) and bunions

BACKGROUND

Hallux valgus is classified as an abnormal deviation of the great toe (hallux) towards the midline of the foot.

OBJECTIVES

To identify and evaluate the evidence from randomised trials of interventions used to correct hallux valgus.

SEARCH STRATEGY

We searched the Cochrane Musculoskeletal Injuries Group trials register (2003/1), the Cochrane Central Register of Controlled Trials (The Cochrane Library issue 1, 2003), MEDLINE (January 1966 to March 2003) and EMBASE (1980 to January 2003). No language restrictions were applied. Hand searching of specific foot journals was also undertaken. Date of the most recent search: 31st March 2003.

SELECTION CRITERIA

Randomised or quasi-randomised trials of both conservative and surgical treatments of hallux valgus. Excluded were studies comparing areas of surgery not specific to the control of the deformity such as use of anaesthetics or tourniquet placement.

DATA COLLECTION AND ANALYSIS

Methodological quality of trials which met the inclusion criteria was independently assessed by two reviewers. Data extraction was undertaken by two reviewers. The trials were grouped according to the interventions being compared, but the dissimilarity in the comparisons prevented pooling of results.

MAIN RESULTS

The methodological quality of the 21 included trials was generally poor and trial sizes were small. Three trials involving 332 participants evaluated conservative treatments versus no treatment. There was no evidence of a difference in outcomes between treatment and no treatment. One good quality trial involving 140 participants compared surgery to conservative treatment. Evidence was shown of an improvement in all outcomes in patients receiving chevron osteotomy compared with those receiving orthoses. The same trial also compared surgery to no treatment in 140 participants. Evidence was shown of an improvement in all outcomes in patients receiving chevron osteotomy compared with those receiving no treatment. Two trials involving 133 people with hallux valgus compared Keller's arthroplasty with other surgical techniques. In general, there was no advantage or disadvantage using Keller's over the other techniques. When the distal osteotomy was compared to Keller's arthroplasty, the osteotomy showed evidence of improving the intermetatarsal angle and preserving joint range of motion. The arthroplasty was found to have less of an impact on walking ability compared to the arthrodesis. Six trials involving 309 participants compared chevron (and chevron-type) osteotomy with other techniques. The chevron osteotomy offered no advantages in these trials. For some outcomes, other techniques gave better results. Two of these trials (94 participants) compared a type of proximal osteotomy to a proximal chevron osteotomy and found no evidence of a difference in outcomes between techniques. Three trials involving 157 participants compared outcomes between original operations and surgeon's adaptations. There was no advantage found for any of the adaptations. Three trials involving 71 people with hallux valgus compared new methods of fixation to traditional methods. There was no evidence that the new methods of fixation were detrimental to the outcome of the patients. Four trials involving 162 participants evaluated methods of post-operative rehabilitation. The use of continuous passive motion appeared to give an improved range of motion and earlier recovery following surgery. Early weightbearing or the use of a crepe bandage were not found to be detrimental to final outcome.

REVIEWER'S CONCLUSIONS

Only a few studies had considered conservative treatments. The evidence from these suggested that orthoses and night splints did not appear to be any more beneficial in improving outcomes than no treatment. Surgery (chevron osteotomy) was shown to be beneficial compared to orthoses or no treatment, but when compared to other osteotomies, no technique was shown to be superior to any other. Only one trial had compared an osteotomy to an arthroplasty. There was limited evidence to suggest that the osteotomy gat the osteotomy gave the better outcomes. It was notable that the numbers of participants in some trials remaining dissatisfied at follow-up were consistently high (25 to 33%), even when the hallux valgus angle and pain had improved. A few of the more recent trials used assessment scores that combine several aspects of the patients outcomes. These scoring systems are useful to the clinician when comparing techniques but are of dubious relevance to the patient if they do not address their main concern and such scoring systems are frequently unvalidated. Only one study simply asked the patient if they were better than before the treatment. Final outcomes were most frequently measured at one year, with a few trials maintaining follow-up for 3 years. Such time-scales are minimal given that the patients will be on their feet for at least another 20-30 years after treatment. Future research should include patient-focused outcomes, standardised assessment criteria and longer surveillance periods, more usefully in the region of 5-10 years.

Costs of resistance in insect-parasite and insect-parasitoid interactions

Most, if not all, organisms face attack by natural enemies and will be selected to evolve some form of defence. Resistance may have costs as well as its obvious benefits. These costs may be associated with actual defence or with the maintenance of the defensive machinery irrespective of whether a challenge occurs. In this paper, the evidence for costs of resistance in insect-parasite and insect-parasitoid systems is reviewed, with emphasis on two host-parasitoid systems, based on Drosophila melanogaster and pea aphids as hosts. Data from true insect-parasite systems mainly concern the costs of actual defence; evidence for the costs of standing defences is mostly circumstantial. In pea aphids, the costs of standing defences have so far proved elusive. Resistance amongst clones is not correlated with life-time fecundity, whether measured on good or poor quality plants. Successful defence by a D. melanogaster larva results in a reduction in adult size and fecundity and an increased susceptibility to pupal parasitoids. Costs of standing defences are a reduction in larval competitive ability though these costs only become important when food is limited. It is concluded that costs of resistance can play a pivotal role in the evolutionary and population dynamic interactions between hosts and their parasites.

Clonal variation and covariation in aphid resistance to parasitoids and a pathogen

The potential rate of evolution of resistance to natural enemies depends on the genetic variation present in the population and any trade-offs between resistance and other components of fitness. We measured clonal variation and covariation in pea aphids (Acyrthosiphon pisum) for resistance to two parasitoid species (Aphidius ervi and A. eadyi) and a fungal pathogen (Erynia neoaphidis). We found significant clonal variation in resistance to all three natural enemies. We tested the hypothesis that there might be trade-offs (negative covariation) in defensive ability against different natural enemies, but found no evidence for this. All correlations in defensive ability were positive, that between the two parasitoid species significantly so. Defensive ability was not correlated with fecundity. A number of aphid clones were completely resistant to one parasitoid (A. eadyi), but a subset of these failed to reproduce subsequently. We discuss the factors that might maintain clonal variation in natural enemy resistance.

Triflusal vs. Aspirin for the Prevention of Infarction: a Randomized Stroke Study (TAPIRSS)

P208

Background: TAPIRSS is a randomized, double-blind, multicenter pilot trial designed to study the efficacy of triflusal for the prevention of secondary ischemic stroke conducted in Buenos Aires, Argentina. Triflusal is an antiplatelet agent structurally related to aspirin. Methods and Results: From October 1996 to October 1999 patients were randomized to group #1 (aspirin therapy, 325 mg/daily) or group #2 (triflusal, 600 mg/daily). All patients had experienced either an ischemic stroke (80.9%) or a transient ischemic attack within 6 months prior to randomization. Patients were treated for a median of 586 days. Data for 429 patients were analyzed. Primary endpoints were: cardiovascular death 3.7%(#1)/2.3%(#2)[OR=1.6]; cerebral ischemic infarction 7.4%(#1)/8.0%(#2)[OR=0.92]; non-fatal myocardial infarction 2.3%(#1)/1.9%(#2)[OR=1.24];severe hemorrhage any kind 3.2%(#1)/0.5%(#2)[OR=7.1][p=0.068]. Secondary endpoints were: non-vascular death 2.4%(#1)/0.5%(#2)[OR=5.02]; non-severe hemorrhage 6.0%(#1)/2.3%(#2)[OR=2.66][p=0.058]; systemic thromboembolism 0.9%(#1)/1.4%(#2)[OR=0.65]. Aggregate analysis of primary endpoints showed no significant differences between aspirin and triflusal. Aggregate analysis of secondary enpoints showed a significant difference in favor of triflusal [p=0.038]. Analysis of the combination severe and non-severe hemorrhage showed a significantly reduced incidence of hemorrhagic events with triflusal [8.3%(#1)/2.8%(#2), p=0.013]. Dyspepsia and gastrointestinal discomfort were the most common adverse events in the triflusal group. Conclusions: Triflusal shows a protective effect similar to aspirin in the prevention of secondary ischemic stroke with a lesser risk of hemorrhagic complications. Also, triflusal may be safe for the primary prevention of ischemic stroke.

Benzophenone glycosides from Gnidia involucrata

Six compounds have been isolated from the methanol extract of the aerial parts of Gnidia involucrata (Thymelaeaceae). They were identified as 2,3,4',5,6-pentahydroxybenzophenone-4-C-glucoside and 2,4',6-trihydroxy-4-methoxybenzophenone-2-O-glucoside, together with mangiferin, kaempferol-3-O-glucoside, yuankanin and manniflavanone by chemical and spectroscopic means. The structures of three additional C-glycosyl flavones--vitexin, isovitexin and isoorientin--were determined on-line by LC/UV/APCI-MSn analysis of the crude extract.

Interventions for treating hallux valgus (abductovalgus) and bunions

BACKGROUND

Hallux valgus is classified as an abnormal deviation of the great toe (hallux) towards the midline of the foot.

OBJECTIVES

To identify and evaluate the evidence from randomised trials of interventions used to correct hallux valgus.

SEARCH STRATEGY

Medline (1966-October 1998), Embase (1980-1998), Cinahl (1982-1998), Amed (1993-1998), the Cochrane Controlled Trials Register, the Cochrane Musculoskeletal Injuries Trials Register and bibliographies of identified trials were searched. Hand searching of podiatry journals was undertaken. Date of the most recent search: October 1998.

SELECTION CRITERIA

Randomised or quasi-randomised trials of both conservative and surgical treatments of hallux valgus. Excluded were studies comparing areas of surgery not specific to the control of the deformity such as use of anaesthetics or tourniquet placement.

DATA COLLECTION AND ANALYSIS

Methodological quality of trials which met the inclusion criteria was independently assessed by two reviewers. Data extraction was undertaken by one reviewer and confirmed by another. The trials were grouped according to the interventions being compared, but the dissimilarity in the comparisons prevented pooling of results.

MAIN RESULTS

The methodological quality of the 12 included trials was poor and trial sizes were small. Two trials involving 150 patients evaluated conservative treatments. There was no difference in outcomes between treatment and no treatment. Two trials involving 133 patients compared Keller's arthroplasty with other surgical techniques. In general, there was no advantage in using Keller's over the other techniques, particularly in terms of range of motion and intermetatarsal angle. Three trials involving 205 patients compared chevron (and chevron-type) osteotomy with other techniques. The chevron osteotomy offered no advantages in these trials. For some outcomes, other techniques gave better results. Three trials involving 157 patients compared outcomes between original operations and surgeon's adaptations. There was no advantage found for any of the adaptations. Two trials involving 95 patients evaluated methods of post-operative rehabilitation. The use of continuous passive motion appeared to give an improved range of motion and earlier recovery following surgery; early weightbearing was not found to be detrimental to final outcome.

REVIEWER'S CONCLUSIONS

There is insufficient evidence from randomised trials to determine which methods of either conservative, operative or post-operative treatment are the most appropriate for the hallux valgus. It is notable that the numbers of patients remaining dissatisfied at follow-up were consistently high (25 to 33%), even when the hallux valgus angle and pain had improved. Assessment of future research should focus on evaluating basic intervention types in eligible patients with similar degrees of deformity. Future research should include patient-focused outcomes, standardised assessment criteria and longer surveillance periods.

Sialidase gene transfection enhances epidermal growth factor receptor activity in an epidermoid carcinoma cell line, A431

Glycosphingolipids expressed in cancer cells have been implicated in the modulation of tumor cell growth through their interaction with transmembrane signaling molecules such as growth factor receptors. For glycosphingolipids to interact with growth factor receptors, the presence of sialic acid seems to be essential. Stable transfection of a gene encoding a soluble Mr 42,000 sialidase into a human epidermoid carcinoma cell line (A431) provided an approach by which the level of terminal lipid-bound sialic acid on the cell surface could be altered. In the sialidase-positive clones, the level of ganglioside GM3 was diminished, and little change was observed in protein sialylation. Sialidase-transfected cells grew faster than control cells. Sialidase expression did not modify the binding of epidermal growth factor (EGF) to its receptor but enhanced EGF receptor (EGFR) tyrosine autophosphorylation as compared to that of parental cells or cells transfected with the vector (pcDNA3) alone. Moreover, the phosphorylation of the EGFR, as well as other protein substrates, was observed at low EGF concentrations, suggesting an increase in the receptor kinase sensitivity. These data provided evidence that changes in ganglioside expression in cancer cells by appropriate gene transfection can dramatically affect EGFR kinase activity. Hence, the modulation of ganglioside expression may represent an approach to alter tumor cell growth.

Chinese hamster ovary cells with constitutively expressed sialidase antisense RNA produce recombinant DNase in batch culture with increased sialic acid

Under some cell culture conditions, recombinant glycoprotein therapeutics expressed in Chinese hamster ovary (CHO) cells lose sialic acid during the course of the culture (Sliwkowski et al., 1992; Munzert et al., 1996). A soluble sialidase of CHO cell origin degrades the expressed recombinant protein and has been shown to be released into the culture fluid as the viability of the cells decreases. To reduce the levels of the sialidase and to prevent desialylation of recombinant protein, a CHO cell line has been developed that constitutively expresses sialidase antisense RNA. Several antisense expression vectors were prepared using different regions of the sialidase gene. Co-transfection of the antisense constructs with a vector conferring puromycin resistance gave rise to over 40 puromycin resistant clones that were screened for sialidase activity. A 5' 474 bp coding segment of the sialidase cDNA, in the inverted orientation in an SV 40-based expression vector, gave maximal reduction of the sialidase activity to about 40% wild-type values. To test if this level of sialidase would lead to increased sialic acid content of an expressed recombinant protein, the 474 antisense clone was employed as a host for expression of human DNase as a model glycoprotein. The sialic acid content of the DNase produced in the antisense cultures was compared with material made in the wild-type parental cell line. About 20-37% increase in sialic acid content, or 0.6-1.1 mole of additional sialic acid out of a total of 3.0 mole on the product, was found on the DNase made in the antisense cell lines.

Anisotropic speckle patterns in the light scattered by rough cylindrical surfaces

Speckle patterns in the light field scattered from the rough surface of a cylindrical object are experimentally studied. The light speckles are elongated in the direction normal to the cylinder axis. A theoretical model explains the main features of the scattered light field. The dimensions of light speckles depend on both the surface roughness and the surface curvature.

Optical-fiber diameter determination by scattering at oblique incidence

A new nondestructive method for determination of the outer diameter of optical fibers is described. The principle of this technique is based on observing interference maxima in the scattered light from a fiber that is side illuminated by a laser beam at oblique incidence. This technique is easy to implement and can be applied to a fiber with an inhomogeneous and large core.

Cloning and expression of a soluble sialidase from Chinese hamster ovary cells: sequence alignment similarities to bacterial sialidases

A cDNA encoding a soluble sialidase from Chinese hamster ovary (CHO) cells has been cloned and expressed. Completely degenerate oligonucleotide primers, which were based on the amino acid sequence of peptides obtained from the purified sialidase (Warner et al., Glycobiology, 3, 455-463, 1993), and the polymerase chain reaction, with single-stranded cDNA template, were employed to generate a unique oligonucleotide probe. The unique probe of 93 bp was used for screening a lambda gt 10 CHO cell cDNA library. A single clone, which contained a 1.4 kb insert, was isolated after screening 450,000 recombinants. The complete coding region of the protein, 1137 nucleotides, was contained in the isolated clone and it predicted a protein of 379 amino acids. The insert had a 186 bp 5' non-coding leader sequence and a 40 bp 3' non-coding region. No signal peptide was identified in the insert, suggesting a cytosolic localization for the protein. No significant primary sequence identities were observed when the deduced amino acid sequence of the CHO cell sialidase was compared with other mammalian proteins or microbial sialidases. However, the protein had significant sequence alignment similarity with several bacterial sialidases. Two 'Asp box' motifs in the CHO cell sialidase had a remarkable alignment positioning in the protein sequence with the similar motifs of the Salmonella LT2 and Clostridium perfringens sialidases. High levels of the enzyme were expressed in Spodoptera frugiperda cells infected with a modified Autographa californica nuclear polyhedrosis virus harbouring the sialidase cDNA.

Isolation and properties of a soluble sialidase from the culture fluid of Chinese hamster ovary cells

A soluble sialidase that can degrade recombinant glycoproteins expressed in Chinese hamster ovary (CHO) cells has been isolated and purified to near homogeneity from the cell culture fluid of this host. Purification of approximately 34,000-fold was carried out using conventional purification techniques including sequential DEAE-Sepharose and S-Sepharose ion-exchange chromatography, followed by hydrophobic interaction chromatography with Phenyl-Toyopearl. Final purification was achieved by heparin-agarose and chromatofocusing chromatography. The minimum molecular weight of the sialidase on SDS-PAGE was approximately 43,000 Da. When the final preparation was examined under non-denaturing conditions, two major (pI = 6.8 and 7.0) and five minor electrophoretic forms with different isoelectric points were identified. The basis for the electrophoretic heterogeneity is not known, but it was not due to carbohydrate diversity since no carbohydrates were detected on the purified protein. The enzyme degraded a variety of sialyl-conjugate substrates, at a pH optimum of 5.9, including intact glycoproteins, oligosaccharides and gangliosides with a 4-fold preference for 2,3- versus 2,6-linked sialic acid residues. With ganglioside substrates, internally linked sialic acid residues were not cleaved by the enzyme. Delineation of this enzyme from the lysosomal and plasma membrane sialidases was made using inhibition studies with C-9 substituted 5-acetamido-2,6-anhydro-3,5-dideoxy-D-glycero-D-galacto-non-2- enonic acid derivatives. The enzyme was identified in several CHO cell lines by immunoblotting using antiserum raised against a synthetic peptide based on amino acid sequence of a fragment derived by trypsin digestion of the purified sialidase.(ABSTRACT TRUNCATED AT 250 WORDS)

Synergistic influence of epidermal growth factor, insulin and transferrin on human fetal kidney in culture

In human fetal kidneys (15-21 weeks of gestation) maintained in serum-free organ culture, protein synthesis remained relatively constant, but DNA synthesis decreased dramatically after 2 days. The addition of transferrin alone had no influence, but insulin and epidermal growth factor (EGF) both significantly stimulated DNA and protein synthesis. When supplemented in combination, transferrin strongly potentiated the insulin effect and after 5 days of culture DNA synthesis was practically restored to values observed in control uncultured renal explants (day 0). When EGF, a potent mitogen, was added as a third factor, the stimulating effectiveness of the (insulin plus transferrin) combination was significantly reduced. However, EGF had no such inhibiting influence on protein synthesis. Differentiation of brush border membranes, as evaluated by hydrolase activities, was not importantly induced nor retarded by any of the three factors supplemented either alone or in combination. The present results indicate that the individual effects of the three factors are not additive, but suggest that they rather act synergistically through a complex mechanism of receptor cross-talk. In our laboratory, there is convincing indication that the response of fetal organs varies according to age, proliferative state of tissues as well as stage of differentiation.

Insulin and transferrin restore important cellular functions of human fetal kidney in serum-free organ culture

A model previously developed in our laboratory to culture human fetal kidneys in serum-free chemically defined medium was used to evaluate the direct influence of potential regulators on nephrogenesis. The aim of the present work was to verify the effects of insulin and transferrin, two hormones considered as essential in other serum-free culture systems. Explants of renal cortex from human fetuses (15-21 weeks) were cultured for 2 and 5 days in serum-free Leibovitz's L-15 medium (37 degrees C, 95% air - 5% CO2). The addition of transferrin (5 micrograms/mL) had no effect, but insulin (30, 60, and 125 mU/mL) increased DNA and protein syntheses in a dose-dependent manner. The influence of insulin (125 mU/mL) was potentiated by the addition of transferrin and the combination of the two stimulated DNA synthesis by threefold on day 2 when compared with controls and by sixfold on day 5 of culture. After 5 days, synthesis was restored to values observed at day 0. Transferrin did not modify the insulin effect on protein synthesis, since the latter was already maximally stimulated as early as day 2 of culture and at levels well above that of uncultured explants (day 0). The activities of four hydrolases considered as markers of brush border differentiation were not importantly changed by any of the hormones, supplemented alone or in combination. The results indicate that proliferation rather than differentiation is the parameter mostly influenced by these two hormones. The combination of insulin plus transferrin restores cellular functions of human fetal kidney explants cultured in serum-free medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal mouse kidney maturation in vitro: coordinated influences of epidermal growth factor, transferrin and hydrocortisone

We have investigated the individual and combined actions of epidermal growth factor (EGF), transferrin and hydrocortisone on the maturation of whole fetal mouse metanephroi maintained in serum-free conditions for up to 5 days. The presence of EGF (100 ng/ml) resulted in elevated levels of [3H]-thymidine incorporation when compared to controls; autoradiograms showed that the proliferation of mesenchymal cells in the nephrogenic zone is particularly enhanced as verified by cell counting. Brush border hydrolase activities (alkaline phosphatase and gamma-glutamyltransferase), on the other hand, were significantly diminished. Transferrin (5 micrograms/ml) slightly stimulated DNA synthesis and potentiated EGF mitogenic action. The activation of DNA replication by the growth factor seems to be mediated through the protein kinase C pathway. When added alone, hydrocortisone (10(-6) M) strongly inhibited DNA synthesis, stimulated hydrolase activities and exerted a positive effect on brush border differentiation. When combined with EGF or to EGF + transferrin, hydrocortisone counteracted the effects of these latter peptides on DNA synthesis and enzyme activities. Considering the earlier observation of a reciprocal relation between proliferation and differentiation during the neotubulogenic phase of kidney development, the results described in the current study suggest that synergistic and synarchic actions of these heterologous factors are involved in the regulation of tubulogenesis.

Mouse fetal kidneys in serum-free organ culture: effects of epidermal growth factor and hydrocortisone

1. The present study was undertaken to determine whether epidermal growth factor (EGF, 100 ng/ml) or hydrocortisone (HC, 10(-8)-10(-5) M) directly influence proliferation and differentiation of mouse fetal kidney maturing in serum-free organ culture. 2. Addition of EGF to the medium significantly stimulated DNA synthesis after 2 and 5 days of culture. Labelled nuclei were mainly localized in the mesenchymal tissue. Protein synthesis remained unchanged. Activities of three hydrolases, markers of brush border differentiation, were reduced. 3. Hydrocortisone (HC), at all concentrations used, significantly inhibited DNA synthesis. Labelled nuclei were distributed in various cell populations of both control and treated explants. Protein synthesis was stimulated by 10(-7) M after 5 days of culture. Hydrolase activities were slightly modified by HC treatment. 4. The present results indicate that EGF stimulates whereas HC decreases proliferation. Both factors have regulatory effects on brush border maturation. 5. Thus, this culture model is a valuable tool for the study of nephrogenesis.

Developmental profile of DNA synthesis and hydrolase activities in human fetal kidney

This study provides original data on human fetal kidney developing during the 13th to 18th week of gestation. The parameters evaluated were DNA synthesis and the activities of 5 hydrolases which are considered as good markers of the brush border membrane differentiation. The conclusions are that DNA synthesis decreased slightly from the 16th to 18th week. The activities of maltase, trehalase, alkaline phosphatase and leucylnapthylamidase remained nearly stable during the studied period. Only the gamma-glutamyltransferase activity decreased significantly between the 15th and 16th week, then it returned close to the 13th week value. The current results suggest that during the 13-18 week period of gestation, cell proliferation is slowed down while maturation of some enzymic activities of the brush border are not importantly modified. The present basic data might be used as reference standards by investigators in the field of human nephrogenesis.

Epidermal growth factor (EGF) influences DNA synthesis in human fetal kidneys maturing in serum-free organ culture

Human fetal kidney explants (13-17 weeks of gestation) were maintained in serum-free organ culture. The influence of epidermal growth factor (EGF) was determined after 2 and 5 days by evaluating DNA and protein synthesis as well as the activities of five brush border hydrolases. During the studied period the overall morphology was preserved and the analysed parameters remained constant. Only DNA synthesis decreased after 2 days. The addition of EGF to the medium did not change any of the cell activities, except DNA synthesis. In fact, the incorporation of [3H]thymidine was significantly stimulated by 105% in 5-day explants cultured in the presence of the growth factor. These results indicate that EGF directly influences proliferation but not maturation of brush border enzymes in fetal human kidneys in culture.

On the presence of intermediate cells in the small intestine

In the small intestine, the presence of transitional cells or cells intermediate between Paneth cells and goblet cells has been reported frequently for 100 years. Light microscopy and, more recently, fine structural studies have indicated that secretory granules observed in intermediate cells share some morphologic characteristics with those of granular goblet cells and of Paneth cells. In order to verify if intermediate cells in the jejunum and ileum of the adult mouse have functional similarities with either granular goblet or Paneth cells, we have studied the incorporation of sulfur-35 by radioautography and the localization of lysozyme by immunocytochemistry. After radioautography, goblet cells and, to a lesser extent, granular goblet cells had incorporated sulfur-35, whereas Paneth cells and intermediate cells were completely negative. Immunolocalization of lysozyme was done by using rabbit anti-rat lysozyme and protein A-peroxidase. After demonstration of peroxidase activity, only Paneth cells were stained and intermediate cells were negative. Therefore, intermediate cells do not contain sulfomucin or lysozyme, and they are functionally different from goblet and Paneth cells. Their function remains unknown.

Comparison between mouse kidneys of pre- and postnatal ages maturing in vivo and in serum-free organ culture

1. To evaluate the influence of age, DNA synthesis and brush border hydrolase activities were determined in mouse kidneys maturing in vivo and in serum-free organ culture. 2. DNA synthesis decreased with advancing age. 3. The protein content and leucylnaphthylamidase, maltase, trehalase, alkaline phosphatase and gamma-glutamyltransferase activities increased with aging. 4. The differences due to age were reproduced in kidneys maturing in culture. 5. These results show that age has a significant effect on the parameters determined, but apparently has no influence on the viability of the kidney explants in culture.

Adrenergic regulation of distention-induced gastrin release in humans

To investigate the possible role of adrenergic nerves in neurally mediated gastrin release, we evaluated the effect of selective adrenergic blockade on the serum gastrin response to gastric distention in healthy human subjects. On separate days, 2 mg of propranolol (beta-adrenergic antagonist), 5 mg of phentolamine (alpha-adrenergic antagonist), or saline (control) was injected intravenously just before distending the stomach with 700 ml of isotonic saline. For 30 min following distention, intragastric pH was kept constant at 5.0 by in vivo titration. Propranolol reduced distention-induced gastrin release by approximately 90% (p less than 0.02), whereas phentolamine had no significant effect on the gastrin response to distention. In additional experiments, we evaluated the effect of the same doses of propranolol or phentolamine on the exaggerated gastrin response to gastric distention that occurred during cholinergic blockade with atropine. In the presence of atropine (2.3 microgram/kg i.v.), propranolol significantly (p less than 0.01) reduced distention-induced gastrin release, whereas phentolamine significantly enhanced the gastrin response to distention (p less than 0.01). We conclude that: (1) distention-induced gastrin release was reduced by propranolol, suggesting that gastric distention releases gastrin by a beta-adrenergic mechanism and (2) distention-induced gastrin release was enhanced by phentolamine, but only in the presence of atropine. Thus, adrenergic nerves appear to regulate the gastrin response to gastric distention in humans: beta-adrenergic pathways stimulate gastrin release, and alpha-adrenergic pathways may inhibit gastrin release under certain circumstances.

Bombesin stimulates human gastric function by gastrin-dependent and independent mechanisms

Studies were performed in six men to determine the relationship between serum gastrin concentration and gastric function during exogenous and endogenous stimulation of gastrin release. When the intragastric pH was maintained at 5.0, there were dose-related increases in gastric acid secretion with increasing serum gastrin concentrations produced either by stepwise increasing doses of intravenous gastrin or bombesin, or by intragastric perfusion with peptone. When intragastric pH was maintained at 2.5, or when intravenous atropine was given hourly, sensitivity to both exogenous and endogenously released gastrin were similarly decreased. Gastric emptying was inhibited in a dose-dependent manner by both bombesin and peptone but not by exogenous gastrin. These results suggest that bombesin and peptone stimulate gastric acid secretion through release of circulating gastrin but inhibit gastric emptying by another mechanism.