The clinical and molecular spectrum of the KDM6B-related neurodevelopmental disorder

De novo variants are a leading cause of neurodevelopmental disorders (NDDs), but because every monogenic NDD is different and usually extremely rare, it remains a major challenge to understand the complete phenotype and genotype spectrum of any morbid gene. According to OMIM, heterozygous variants in KDM6B cause "neurodevelopmental disorder with coarse facies and mild distal skeletal abnormalities." Here, by examining the molecular and clinical spectrum of 85 reported individuals with mostly de novo (likely) pathogenic KDM6B variants, we demonstrate that this description is inaccurate and potentially misleading. Cognitive deficits are seen consistently in all individuals, but the overall phenotype is highly variable. Notably, coarse facies and distal skeletal anomalies, as defined by OMIM, are rare in this expanded cohort while other features are unexpectedly common (e.g., hypotonia, psychosis, etc.). Using 3D protein structure analysis and an innovative dual Drosophila gain-of-function assay, we demonstrated a disruptive effect of 11 missense/in-frame indels located in or near the enzymatic JmJC or Zn-containing domain of KDM6B. Consistent with the role of KDM6B in human cognition, we demonstrated a role for the Drosophila KDM6B ortholog in memory and behavior. Taken together, we accurately define the broad clinical spectrum of the KDM6B-related NDD, introduce an innovative functional testing paradigm for the assessment of KDM6B variants, and demonstrate a conserved role for KDM6B in cognition and behavior. Our study demonstrates the critical importance of international collaboration, sharing of clinical data, and rigorous functional analysis of genetic variants to ensure correct disease diagnosis for rare disorders.

Individual with Homozygous TECR Variant Expands Upon the Existing Phenotype for a Hutterite Founder Mutation

Intellectual disability (ID) is ubiquitous across nations affecting roughly 1 percent of the world's population. Improvements in genetic testing methodologies have led to increased understanding about the etiology of ID. However, many cases remain idiopathic. We describe the first individual outside of an existing sibship with a homozygous TECR variant; c.545C>T. Similar to the previously described sibship, this individual is of Hutterite ancestry; suggesting that TECR-related ID is due to a founder mutation. The phenotypic spectrum is expanded to include dolicocephaly and dysgenesis of the corpus callosum. First-tier genetic testing (chromosomal microarray) identified multiple regions of homozygosity (ROH); however, the diagnosis was made by second-tier sequencing in a gene outside of any ROH. The authors advocate for the use of second-tier sequencing in cases of ID in the absence of major congenital anomalies or the presence of consanguinity and/or a limited gene pool. At the very least, sequencing of the TECR gene should be included in the diagnostic workup for individuals with Hutterite ancestry presenting with ID.

Osteochondrosis lesions of the lateral trochlear ridge of the distal femur in four ponies

Lesions of the lateral trochlear ridge (LTR) of the distal femur were investigated in four pony or pony cross horses. The animals were all geldings and were six to 15 months of age. Lesions were bilateral in three ponies and unilateral in one. Femoropatellar joint effusion and lameness were present in two ponies; clinical signs were absent in the others. The proximal LTR was affected in all four animals. The radiographic appearance of the lesions was a subchondral defect containing mineralised bodies. Arthroscopic and postmortem examination findings included an osteochondral flap, a fissured or irregular articular surface and a smooth surface overlying focally thickened cartilage that extended into subchondral bone. Thickened articular cartilage was a histological feature of all the lesions. Among the other histological features, the most common were chondronecrosis, chondrocyte clusters, phenotypically abnormal chondrocytes, horizontal fissures at the osteochondral junction and retained blood vessels. The signalment of the four ponies, their clinical signs and the pathological features of their lesions were consistent with osteochondrosis of the LTR in horses. The use of multiple criteria was considered to be important in making a specific diagnosis.

Osteoarthritis of the talocalcaneal joint in 18 horses

REASONS FOR PERFORMING STUDY

Talocalcaneal osteoarthritis (TO) is an uncommon cause of moderate to severe hindlimb lameness, on which only isolated case reports have been published to date.

OBJECTIVES

To review the clinical features of TO and determine optimal methods for diagnosis, management and prognosis.

METHODS

The case records from 4 referral centres of 18 horses showing hindlimb lameness considered, as a result of clinical investigation, to be caused by TO, were reviewed.

RESULTS

TO affected mature sports and pleasure horses (age 7-16 years) and caused moderate to severe lameness, usually of sudden onset with no obvious inciting cause. There were few localising signs, other than worsening of lameness by hock flexion. Tarsocrural joint analgesia produced improvement in lameness in 6/11 horses (55%) and perineural analgesia of the tibial and fibular nerves complete soundness in 6/14 horses (43%) in which it was performed; 7/14 horses (50%) showed a further substantial improvement. Radiological findings included subchondral bone lysis and sclerosis and irregular joint space width, seen most obviously in a lateromedial view. Nuclear scintigraphy revealed marked uptake of radiopharmaceutical predominantly plantaromedially in the region of the talus in the 7 horses in which it was performed. Fourteen horses were treated conservatively with box- or pasture-rest, with or without intra-articular corticosteroids, hyaluronic acid or polysulphated glycosaminoglycan, and all remained lame. Intra-articular corticosteroids appeared to have no effect in any horse. Of 10 horses receiving conservative management only, 6 were subjected to euthanasia, 3 were retired and 1 remained in light work, but was still lame. Two horses treated by either partial tibial and fibular neurectomy or subchondral forage failed to regain soundness and were retired. Six horses were treated by surgical arthrodesis of the talocalcaneal joint with 2 or three 5.5 mm AO screws introduced obliquely across the joint from the plantarolateral aspect of the calcaneus, which resulted in improvement in lameness in all cases.

CONCLUSIONS

Osteoarthritis of the talocalcaneal joint causes acute onset severe lameness, but clinical findings and diagnostic analgesia often fail to identify precisely the site of pain. Consistent radiographic changes suggested TO was contributing to the lameness and this diagnosis was supported by nuclear scintigraphy. The poor success of conservative treatment (including intra-articular medication) suggests that surgical arthrodesis is the treatment of choice, although the prognosis is still poor for a return to full soundness.

POTENTIAL RELEVANCE

The clinical features described should facilitate more accurate diagnosis and prognosis. A novel surgical treatment is described which appears to offer significant improvement in the lameness. Further work is necessary to determine the causes of this condition and more effective management.

PCA and clustering reveal alternate mtDNA phylogeny of N and M clades

Phylogenetic trees based on mtDNA polymorphisms are often used to infer the history of recent human migrations. However, there is no consensus on which method to use. Most methods make strong assumptions which may bias the choice of polymorphisms and result in computational complexity which limits the analysis to a few samples/polymorphisms. For example, parsimony minimizes the number of mutations, which biases the results to minimizing homoplasy events. Such biases may miss the global structure of the polymorphisms altogether, with the risk of identifying a "common" polymorphism as ancient without an internal check on whether it either is homoplasic or is identified as ancient because of sampling bias (from oversampling the population with the polymorphism). A signature of this problem is that different methods applied to the same data or the same method applied to different datasets results in different tree topologies. When the results of such analyses are combined, the consensus trees have a low internal branch consensus. We determine human mtDNA phylogeny from 1737 complete sequences using a new, direct method based on principal component analysis (PCA) and unsupervised consensus ensemble clustering. PCA identifies polymorphisms representing robust variations in the data and consensus ensemble clustering creates stable haplogroup clusters. The tree is obtained from the bifurcating network obtained when the data are split into k = 2,3,4,...,kmax clusters, with equal sampling from each haplogroup. Our method assumes only that the data can be clustered into groups based on mutations, is fast, is stable to sample perturbation, uses all significant polymorphisms in the data, works for arbitrary sample sizes, and avoids sample choice and haplogroup size bias. The internal branches of our tree have a 90% consensus accuracy. In conclusion, our tree recreates the standard phylogeny of the N, M, L0/L1, L2, and L3 clades, confirming the African origin of modern humans and showing that the M and N clades arose in almost coincident migrations. However, the N clade haplogroups split along an East-West geographic divide, with a "European R clade" containing the haplogroups H, V, H/V, J, T, and U and a "Eurasian N subclade" including haplogroups B, R5, F, A, N9, I, W, and X. The haplogroup pairs (N9a, N9b) and (M7a, M7b) within N and M are placed in nonnearest locations in agreement with their expected large TMRCA from studies of their migrations into Japan. For comparison, we also construct consensus maximum likelihood, parsimony, neighbor joining, and UPGMA-based trees using the same polymorphisms and show that these methods give consistent results only for the clade tree. For recent branches, the consensus accuracy for these methods is in the range of 1-20%. From a comparison of our haplogroups to two chimp and one bonobo sequences, and assuming a chimp-human coalescent time of 5 million years before present, we find a human mtDNA TMRCA of 206,000 +/- 14,000 years before present.

[New conjugates of antitumor antibiotic doxorubicin with water-soluble galactomannan: synthesis and biological activity]

New water-soluble conjugates in the form of Schiff bases (DGM-1 and DGM-2) were prepared by the interaction of water-soluble periodate-oxidized galactomannan with doxorubicin or N-(L-lysyl)doxorubicin, respectively. The water-soluble galactomannan (DAVANAT a commercial product of Pro-Pharmaceuticals company) was obtained by partial acidic hydrolysis of high-molecular-mass galactomannan from Cyamopsis tetragonoloba (guar gum) seeds. The conjugate stability was studied in aqueous solutions. The DGM-1 antiproliferative activity was comparable with that of doxorubicin on three models: cell lines of murine melanoma B 16-F1, human breast cancer MCF-7 (HTB-22), and human colon cancer HT-29 (HTB-38). DGM-2 was poorly active in all the three tests. DGM- 1 can thus be regarded as a high-molecular-mass depot form of doxorubicin.

A biodistribution of 5-fluorouracil co-administered with and without galactomannan derivative, in athymic mice implanted with COLO 205 human xenografts

12027

Background: The polysaccharide [(1–4)-linked β-D-mannopyranose]17- [(1–6)-linked-α-D-galactopyranose]10 (Davanat [D]), enhances activity of 5-Fluorouracil (5-FU) in 5-FU refractory murine colon tumor models. D binds to surface lectins and promotes transport of 5-FU into the tumor cells. Lectins are present in large amounts on the surface of metastatic tumor cells, and may mediate cell association, apoptosis and metastasis. Method: A preclinical biodistribution study was initiated to evaluate the intravenous (i.v.) administration of 5-FU (36 mg/kg/dose) in the absence and presence of D (60 mg/kg/dose) in female athymic mice with tumors. Forty mice either received 5-FU alone or with D on days 24–27 (Q1d × 4) after tumor implantation. On day 27, a (2-14C) labeled 5-FU was added to the regimen. After the injection, ten mice per time point (0.5, 1.5, 4 and 24 h) were bled, euthanized and then the plasma, tumor and tissues were assayed for radioactivity by a liquid scintillation analyzer. Objectives were to determine the biodistribution of 14C-5-FU in the absence and presence of D in plasma, tumor and tissues. Results: 14C-5-FU disappeared in a bi-phasic manner after i.v. injection both in the presence and absence of D. Addition of D increased the amount of 5-FU exposure as measured by area under the curve (AUC) from 1.5 to 24 hours post-dose. This finding confirms results from a Phase I study where administering escalating doses 30 to 280 mg/m2 D with fixed 500 mg/m2 5-FU also demonstrated an increase in 5-FU systemic exposure as the D dose increased to 280 mg/m2 Conclusions: In mice, 14C-5-FU dosed with D increased the overall exposure of 14C-5-FU during the 1.5 to 24 hr sampling time duration in plasma, tumor and kidneys, when compared to 14C-5-FU dosed alone. These results, and the results obtained from a Phase I study where D was co-administered with 5-, warrants further testing in a Phase II/III clinical trial.

[Table: see text]

Age Influences the Expression of GAP-43 in the Rat Hippocampus following Seizure

BACKGROUND

Normal aging is associated with impairments in learning and memory and motor function. One viable hypothesis is that these changes reflect an age-related decrease in brain plasticity.

OBJECTIVE

The aim of the present study was to identify age-related changes in the time course of expression of the axonal growth associated protein 43 (GAP-43) in a rat model of brain plasticity.

METHODS

We examined by Northern blotting, in situ hybridization, and immunohistochemistry the effects of age on the time course of the expression GAP-43 following pentylenetetrazole-induced seizure in the hippocampus of 3-, 18-, and 28-month-old rats.

RESULTS

In this model of brain plasticity, young rats displayed a decrease in GAP-43 mRNA levels in CA1, CA3, and polymorphic regions, lasting from 10 h to 3 days after seizure. This was followed by recovery, with peak expression between days 10 and 20. The baseline levels of GAP-43 mRNA decreased with age, especially in the CA3 region. Despite lower baseline levels, middle-aged rats showed the same pattern of upregulation of GAP-43 mRNA expression as the young animals. Old rats showed only minimal upregulation, however, and this occurred only in the polymorphic layer. The level GAP-43 protein itself was higher in old control rats than in the other two control groups, a condition that was transiently reversed by seizure activity.

CONCLUSIONS

Middle-aged rats are still capable of a sustained, though diminished, response to seizure activity, while old rats lose this ability. Disruption of the temporal and anatomical coordination of expression of GAP-43 may contribute to the general decline in brain plasticity with age.

On the efficacy of piracetam in geriatric patients with acute cerebral ischemia: a clinically controlled double-blind study

Using a randomized, double blind group comparison, the efficacy and tolerance of piracetam as an additional therapy of hydroxyethyl starch, venous infusion and low dose heparin treatment, which are the basis of therapy in our hospital, has been studied in patients displaying acute cerebral ischemia. A total of 56 patients were enrolled, of whom 27 were given piracetam and 29 served as a control during a 28-day period. Using single photon emission computer tomography (SPECT) analysis, we observed that in 23 piracetam-treated patients (85.2%) a reduction in the area of brain regions displaying an impaired flow rate occurred (P < 0.001; Fisher's exact two-sided test). Only six of placebo-treated patients (20.7%) showed an improved flow rate. Analysis of the recorded computer tomography map gave an improvement coefficient >2 (flow rate marginally or better improved) for 23 piracetam patients as compared with 5 placebo patients (P < 0.001, Uleman test).

Accelerated accumulation of N- and C-terminal beta APP fragments and delayed recovery of microtubule-associated protein 1B expression following stroke in aged rats

The age-related decline in plasticity of the brain may be one factor underlying poor functional recovery after stroke. In the present work we tested the hypothesis that the attenuation of neural plasticity in old age could be the result of an altered temporal relationship between factors promoting brain plasticity [microtubule-associated protein 1B (MAP1B)] and neurotoxic factors such as C-terminal betaAPP. Focal cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery in 3- and 20-month-old male Sprague-Dawley rats. The functional outcome was assessed in neurobehavioral tests at 3, 7, 14 and 28 days after surgery. At the indicated timepoints, brains were removed and immunostained for C- and N-terminal betaAPP and MAP1B. At 2 weeks poststroke, we found an age-related increase in the amount of the C-terminal fragment of betaAPP in the peri-infarcted area and the infarct core as well as an early, vigorous incorporation of N-terminal betaAPP into the developing astroglial scar. The recovery of the plasticity-associated protein MAP1B following stroke was delayed in both age groups and became prominent between days 14 and 28. As aged rats showed diminished functional recovery compared with young rats, these results suggest that the accumulation of C-terminal betaAPP, together with the early incorporation of N-terminal betaAPP into the glial scar, may over-ride the beneficial role of plasticity factors such as MAP1B.

Temporal Dynamics of Degenerative and Regenerative Events Associated with Cerebral Ischemia in Aged Rats

BACKGROUND AND PURPOSE

The age-related decline in plasticity of the brain may be one factor underlying the poor functional recovery after stroke. In the present work we tested the hypothesis that the attenuation of neural plasticity could be the result of an age-related REDUCTION in the upregulation of factors promoting brain plasticity (microtubule-associated protein 1B [MAP1B], beta-amyloid precursor protein [betaAPP]), and an age-related INCREASE in glial reactivity and the accumulation of Abeta, a proteolytic cleavage product of betaAPP with neurotoxic properties.

METHODS

Focal cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery in 3- and 20-month-old male Sprague-Dawley rats. The functional outcome was assessed in neurobehavioral tests 3, 7, 14 and 28 days after surgery. At the indicated time points, brains were removed and immunostained for glial cells. Abeta, as well as the markers of brain plasticity, betaAPP and MAP1B.

RESULTS

Histologically, in young rats there was a gradual activation of both microglia and astrocytes that peaked by days 14-28 with the formation of a glial scar. In contrast, aged rats showed an accelerated astrocytic and microglial reaction that peaked in the first week after stroke. The expression patterns of a growth-associated phenotype of betaAPP as well as with MAP1B accumulation in varicosities along axons in cortical areas affected by stroke peaked between days 14 and 28 in young animals. In aged rats their expression was both delayed (28 days) and reduced. In addition the carboxy terminal fragment of betaAPP steadily accumulated over time and reached a maximum by day 14 in aged rats as compared to 28 days in young rats.

CONCLUSIONS

These results suggest that a temporally anomalous gliotic reaction to cerebral ischemia in aged rats in conjunction with a late and limited upregulation of neuronal plasticity proteins as well as a diminished neurogenesis potential lead to the prevalence of scar tissue that impedes functional recovery from stroke.

Accelerated glial reactivity to stroke in aged rats correlates with reduced functional recovery

Following cerebral ischemia, perilesional astrocytes and activated microglia form a glial scar that hinders the genesis of new axons and blood vessels in the infarcted region. Since glial reactivity is chronically augmented in the normal aging brain, the authors hypothesized that postischemic gliosis would be temporally abnormal in aged rats compared to young rats. Focal cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery in 3- and 20-month-old male Sprague Dawley rats. The functional outcome was assessed in neurobehavioral tests at 3, 7, 14, and 28 days after surgery. Brain tissue was immunostained for microglia, astrocytes, oligodendrocytes, and endothelial cells. Behaviorally, aged rats were more severely impaired by stroke and showed diminished functional recovery compared with young rats. Histologically, a gradual activation of both microglia and astrocytes that peaked by days 14 to 28 with the formation of a glial scar was observed in young rats, whereas aged rats showed an accelerated astrocytic and microglial reaction that peaked during the first week after stroke. Oligodendrocytes were strongly activated at early stages of infarct development in all rats, but this activation persisted in aged rats. Therefore, the development of the glial scar was abnormally accelerated in aged rats and coincided with the stagnation of recovery in these animals. These results suggest that a temporally anomalous gliotic reaction to cerebral ischemia in aged rats leads to the premature formation of scar tissue that impedes functional recovery after stroke.

The aging liver: structural and functional changes and their consequences for drug treatment in old age

BACKGROUND/OBJECTIVE

Numerous age-related changes in hepatic structure and function have been described, although liver function seems to be quite well maintained in old age. Few consistent and reproducible observations and a lack of correlation between structural and functional data characterize the present state of our knowledge. In contrast to renal clearance, no equally reliable method exists to estimate hepatic drug clearance. The contribution of age to altered drug clearance in the elderly is difficult to assess as drug interactions, numbers and types of drugs taken at a time, underlying disease and increased interindividual variability are superimposed to the aging process.

METHODS

A comprehensive computer-assisted search of the literature.

RESULTS

A decline in liver volume and blood flow and a reduction in in vitro and in vivo metabolic capacity have been shown in older subjects, and the physiologic basis of reduced hepatic drug clearance in this age group.

CONCLUSIONS

After decades of research into the matter, the old and well-known aphorism "start lower--go slower" is valid more than ever in the field of geriatric prescribing. Not only renally excreted drugs but also substances which are metabolized and excreted by the liver should be used at a starting dose which is 30-40% smaller than the average dose used in middle-aged adults.

Bovine Staphylococcus aureus mastitis: strain recognition and dynamics of infection

Restriction enzyme fragmentation pattern (REFP) analysis was used to recognise Staphylococcus aureus strain variation in naturally occurring bovine subclinical mastitis. Multiple colony REFP analysis identified eight distinct strains of S. aureus in addition to the original strains A and B that were infused via the intramammary route, indicating that individual quarters of the udder may be colonised simultaneously by more than one strain of S. aureus. Examination of multiple colonies per milk sample may benefit bacterial strain recognition as an epidemiological tool in mastitis investigations. The dynamics of intramammary infection were determined using a novel double crossover experimental challenge. Quarters remained persistently infected for several weeks following challenge in all four cows, irrespective of the challenge strain. This indicated that no alteration of the original subclinical infection, including the possible induction of clearance of the quarters infected with S. aureus, or replacement of the original strain by the infused strain was induced by challenge. The persistent subclinical infection in all four animals supports previous reports on the chronicity of S. aureus intramammary infection in dairy cows.

Age-associated changes in integral cholesterol and cholesterol sulfate concentrations in human scalp hair and finger nail clippings

In contrast to surface lipids originating from the sebaceous glands, membrane-forming integral lipids occur in keratinized tissues of skin, and skin appendages like fingernail plates or scalp hair. After removal of lipids of sebaceous origin by exhaustive solvent extraction, lyophilizing and hydrolyzing fingernail plate and scalp hair samples, fractions of integral cholesterol (CH) and cholesterol sulfate (CS) were quantified using gas chromatography. We studied these bound lipids and the serum lipids of 70 healthy subjects, aged 20.1 to 92.0 years. We observed higher amounts of CS in hair clippings of men than of women (775+/-241 vs 662+/-239 nmol/g hair, respectively). The highest amounts of CS were found in men with serum LDL-CH > 4.14 mmol/L; this subgroup also showed the highest CH values in fingernail clippings (2293+/-621 nmol/g nail). However, analysis of integral lipids of hair and fingernail plate clippings had little significance in detecting hypercholesterolemia in normal persons. An increase in integral CH levels in fingernail clippings with donor age was noted, independently of variations in serum CH or LDL-CH. This correlation proved to be significant in men (R=0.43), but not in women (R=0.38). In contrast, in women but not in men we found donor age correlated with internal CH of hair samples (R=0.43) and with CS of nail plates (R=-0.59), independently of serum CH or LDL-CH variations. This age-dependent decrease in CS levels might explain the previously observed higher incidence of brittle nails in women. Obviously, the metabolism of internal lipids CH and CS in fingernail and scalp hair differs between genders, and shows age-associated changes.

Determination of cefditoren (ME 1206) in the plasma of elderly patients with multiple diseases using high-performance liquid chromatography

In the present study we developed a new sensitive and selective HPLC-assay for the determination of cefditoren (ME 1206) in the plasma. The column switching technique was used to regenerate the pre-column and the analytical column separately. This method is suitable for pharmacokinetic studies and for drug monitoring. Thus, we measured plasma samples of 15 elderly patients (age range: 67-88 years), receiving cefditoren-pivoxil therapy because of infections of the respiratory tract. In addition, these patients were treated with several co-medications because of further diseases. With our HPLC-method no interfering peaks could be detected at the retention time of cefditoren (10.67 min) or of the internal standard (16.62 min). The lowest plasma concentration of cefditoren to be quantified was 25 ng/ml (R.S.D.= 15.5%, n = 5).

Brain plasticity: to what extent do aged animals retain the capacity to coordinate gene activity in response to acute challenges

The ability of the rodent brain to support plasticity-related phenomena declines with increasing age. A decreased coordination of genes implicated in brain plasticity may be one factor contributing to this decline. Synaptic rearrangement that occurs after seizure activity is regarded as a model of brain plasticity. In a rat model of seizure-related brain plasticity, we found that the induction of immediate-early genes, as exemplified by c-fos and tissue plasminogen activator (TPA) is not impaired in the aged rat brain. However, the aged rat brain responded more slowly to chemically induced seizure and the levels of c-fos and TPA mRNAs induction are decreased in the cortex and in the hippocampus of 30-month-old rats, as compared to the levels expressed by 3-month-old rats. In addition, at the peak induction the TPA transcripts were restricted to certain cortical layers of the older rats. Surprisingly, in applying the same experimental paradigm to late genes we found that there was a shift toward earlier times in the maximum expression of growth-related molecule, the microtubule-associated protein 1B (MAP1B) mRNA, which was very evident in 18-month-old rats. Aberrant immunolabeling of MAP1B occurred in cortical layer VI of the aged rats where, unlike in young rats, there was heavy staining of neuronal somata. These results suggest that (i) one consequence of aging, besides decreases in the levels of mRNA, is a progressive loss of coordination in gene activity following the administration of a stimulus; (ii) since c-fos, TPA and MAP1B have been implicated in neuronal plasticity, these findings could explain, in part, the limited plasticity of the aging brain.

The emergence of pattern discovery techniques in computational biology

In the past few years, pattern discovery has been emerging as a generic tool of choice for tackling problems from the computational biology domain. In this presentation, and after defining the problem in its generality, we review some of the algorithms that have appeared in the literature and describe several applications of pattern discovery to problems from computational biology.

Delayed and blunted induction of mRNA for tissue plasminogen activator in the brain of old rats following pentylenetetrazole-induced seizure activity

The ability of the rodent brain to support plasticity-related phenomena declines with increasing age. Here we investigated the extent to which old rats retain the capacity to initiate transcription for immediate early genes, particularly as it relates to brain plasticity, in response to a strong stimulus. The intraperitoneal administration of pentylenetetrazole (PTZ) to rats of various ages evoked tonic-clonic seizures. Using an RNA gel-blot and in situ hybridization analysis, we found that 1 hour after the onset of seizure, messenger RNA (mRNA) for tissue plasminogen activator (TPA) was increased approximately 3.7-fold in the hippocampi of 3-month-old rats. The levels of TPA mRNA in the hippocampi and cortices of 3-month-old rats returned to control levels by 3 hours after PTZ administration. The levels of TPA mRNA increased 2.5-fold in the hippocampi of 18-month-old rats and 1.8-fold in the brains of the 28-month-old-rats at 3 hours and returned to basal levels by 15 hours following PTZ treatment. Quantitatively similar increases were calculated for the cortex. At peak induction the transcripts were localized throughout the cortical layers of the 3-month-old rats, whereas the TPA mRNA expression was restricted to cortical layer V of the older rats. Our results suggest that although the aging brain retains the capacity to respond to chemically induced seizures, the induction of TPA mRNA is temporarily delayed and the levels are diminished with increasing age. Because TPA has been implicated in neuronal plasticity, this finding suggests that immediate early genes are important factors in the limited plasticity of the aging brain.

Effect of borage oil consumption on fatty acid metabolism, transepidermal water loss and skin parameters in elderly people

Human skin is not able to biosynthesize gamma-linolenic acid (GLA, 18:3omega6) from the precursor linoleic acid (LA), or arachidonic acid (AA) from dihomo-gamma-linolenic acid (DHGLA). Dietary supplementation with GLA-rich seed oil of borage skips the step of hepatic 6-desaturation of fatty acids (FA) and, therefore, compensates the lack of these essential FA in conditions with impaired activity of delta 6-desaturase. Twenty-nine healthy elderly people (mean age 68.6 years), received a daily dose of 360 or 720 mg GLA for 2 months, using Borage oil in gelatine capsules (Quintesal 180, manufacturer Galderma Laboratorium GmbH, Freiburg, Germany). The effects of fatty acids derived from ingested borage oil capsules on skin barrier function were assessed by measurement of transepidermal water loss (TEWL). The consumption of borage oil induced a statistically significant improvement of cutaneous barrier function in the elderly people, as reflected in a mean decrease of 10.8% in the transepidermal water loss. Thirty-four percent of the people noted itch before borage oil consumption and 0% afterwards. Dry skin was claimed to be reduced from 42 to 14%, but no significant alteration of skin hydration was measured. The FA-composition of erythrocyte membrane phospholipids demonstrated an increase of GLA (+70%) and DHGLA (+18%) and a reduction of saturated and monounsaturated FA. There was no significant alteration in nervonic acid or in AA content, but an increase in the DHGLA/AA ratio (+23%). Thus, the consumption of borage oil by elderly people lead to alteration of FA metabolism and improved skin function.

Proton translocating ATPase mediated fungicidal activity of a novel complex carbohydrate: CAN-296

CAN-296 is a complex carbohydrate (approximately 4300 Da) isolated from the cell wall of Mucor rouxii. It exhibits excellent in vitro fungicidal activity against a wide spectrum of pathogenic yeasts, including isolates resistant to azoles and polyenes. The rapid irreversible action of CAN-296 on intact fungal cells and protoplasts suggested a membrane-located target for its action. The proton translocating ATPase (H+-ATPase) of fungi is an essential enzyme required for the regulation of intracellular pH and nutrient transport. Inhibition of H+-ATPase leads to intracellular acidification and cell death. We therefore investigated the effect of CAN-296 on H+-ATPase-mediated proton pumping by intact cells of Candida and Saccharomyces species by measuring the glucose-induced acidification of external medium. CAN-296 inhibited proton pumping of Candida albicans, Candida glabrata, Candida krusei, Candida guilliermondii and Saccharomyces cerevisiae at low concentrations (0.078-1.25 mg/l). Other commonly used antifungal agents such as amphotericin B, itraconazole and fluconazole had no effect on H+-ATPase-mediated proton pumping. A clinical isolate of C. glabrata with reduced in vitro susceptibility (MIC = 10 mg/l) to CAN-296 also showed resistance to CAN-296 inhibition of proton pumping. Purified membrane fractions rich in H+-ATPase activity were not inhibited by CAN-296 suggesting that the effect on the H+-ATPase-mediated proton pumping in intact yeast cells is an indirect effect, perhaps mediated by local or global disruption of the plasma membrane. These results suggest that the inhibition of fungal H+-ATPase is at least partly responsible for the antifungal activity of CAN-296.

Anomalous expression of microtubule-associated protein 1B in the hippocampus and cortex of aged rats treated with pentylenetetrazole

The aim of the present study was to assess the age-dependent response of microtubule-associated protein 1B, a plasticity-associated protein deriving from a late gene, following administration of an epileptogenic stimulus. The effect of a single administration of the convulsant pentylenetetrazole on microtubule-associated protein 1B expression in the hippocampal formation and cortex of three-, 18- and 28-month-old rats was assessed using northern blot analysis, in situ hybridization and immunohistochemistry. In three-month-old rats, we detected initial increases in microtubule-associated protein 1B messenger RNA at 15 h following pentylenetetrazole administration in the granule cells of the dentate gyrus, in the CA3 region of the hippocampus and in layers II/III of the entorhinal cortex, and these reached a maximum at 44 h. However, in the hippocampus and cortex of 18-month-old rats, the peak occurred at 15 h, and in the brains of 28-month-old rats a blunted peak was reached at 3 h. Pentylenetetrazole treatment in young rats resulted in a robust induction of microtubule-associated protein 1B immunoreactivity in the granule cells of the dentate gyrus and in layers II/III of the entorhinal cortex, but also produced a large decrease in the retrosplenial cortex. However, following pentylenetetrazole treatment in older rats, the granule cells of the dentate gyrus were nearly devoid of microtubule-associated protein 1B immunoreactivity, whereas the retrosplenial cortex showed no changes at all, and the entorhinal cortex had an expression pattern similar to that of young rats. Aberrant immunolabeling of microtubule-associated protein 1B occurred in cortical layer VI of the aged rats where, unlike in young rats, there was heavy staining of neuronal somata. These results suggest that the regulation of the plasticity-associated protein microtubule-associated protein 1B is altered in the ageing rat brain, with the peak of expression shifted to earlier times in 18-month-old rats and blunted, variable increases at even earlier times in 28-month-old rats.

Age-dependent changes of the kidneys: pharmacological implications

About 40% of the intoxications after drug administration occur in the elderly. A significant proportion of the disease states in elderly patients is related to adverse reactions to prescribed drugs. Declining renal function, a reduction in both renal blood flow and glomerular filtration rate, is a major contributor to drug toxicity in the elderly. Therefore, a review (based on newer papers from Medline) of age-dependent changes of the kidneys and their consequences for drug therapy in geriatric patients is presented. Renal changes that occur with aging are: a decrease of renal weight, a thickening of the intrarenal vascular intima, sclerogenous changes of the glomeruli, and infiltration of chronic inflammatory cells and fibrosis in the stroma. Altered renal tubular function, including impaired handling of water, sodium, acid, and glucose, is also frequently present in old age. Impaired 'endocrinologic' functioning manifested by changes of the renin-angiotensin system, vitamin D metabolism, and antidiuretic hormone responsiveness has been reported. The aging kidney is constantly exposed to the effects of a variety of potential toxic processes, i.e., drugs and chronic illnesses including hypertension, diabetes, and atherosclerotic disease. Renal changes that occur with aging also consist of impairment in the ability to concentrate urine and to conserve sodium and water. These physiological changes increase the risks of volume depletion and prerenal type of acute renal failure. A frequent cause of acute renal failure in the elderly is drug-induced nephropathy. Nonsteroidal anti-inflammatory drugs, antibiotics, and diuretics are most often involved. Due to the age-dependent decline of renal function, the pharmacokinetics of many drugs are altered in elderly patients. Therefore, the most important renal function to monitor with aging is the creatinine clearance. Changes in pharmacokinetics of many drugs and most decisions on drug dosage can be based on this information alone, as tubular functions of the kidney decrease at rates paralleling the age-dependent decrease in glomerular filtration rate (which is approximately measured by the creatinine clearance). As a conclusion, age-dependent changes of renal function are not only responsible for changes in pharmacokinetics and pharmacodynamics. In many cases, the kidneys are the target organ of adverse drug reactions too.

Involvement of calcium inhibitable binding to the cell wall in the fungicidal activity of CAN-296

CAN-296 is a heat stable, complex carbohydrate (molecular mass 4300 Da) isolated from the cell wall of the filamentous fungus Mucor rouxii. It possesses potent in-vitro fungicidal activity against a wide spectrum of pathogenic yeasts, including azole-resistant isolates of Candida albicans and Candida glabrata. As a preliminary step in the study of the mode of action of this novel antifungal agent, we investigated the effect of various cations on the antifungal activity as well as the binding of CAN-296 to intact cells and cell-wall fractions of C. albicans. The antifungal activity of CAN-296 was inhibited by low concentrations of calcium, magnesium and lithium and by high concentrations of barium, cobalt and manganese, but not by potassium and copper. The calcium-mediated inhibition of the antifungal activity of CAN-296 was readily reversible by the removal of calcium by dialysis, and the fungicidal activity of the inhibited compound was fully restored. The uptake/binding of CAN-296 to intact cells and to the cell-wall fraction of C. albicans was time and concentration dependent. Maximum uptake/binding was obtained at 5 mg/L within 60 min and was associated with the aggregation of intact cells. Washing intact cells and the cell-wall fraction preincubated with radiolabelled CAN-296 with 150-fold excess of unlabelled compound failed to remove CAN-296 associated with the intact cells and the cell-wall fraction, suggesting that the binding of CAN-296 to C. albicans is tight. The uptake/binding of CAN-296 and the drug-mediated aggregation of intact cells were inhibited by calcium in a concentration-dependent manner. The fact that CAN-296 is a fungicidal agent that binds to intact cells and the cell-wall fraction of C. albicans very tightly, together with the observation that calcium was able to inhibit the fungicidal activity as well as the uptake/binding of CAN-296, suggests that the mode of action of this novel antifungal agent may involve interaction with the cell wall of C. albicans.

Installing PACS--lessons learned

In 1997, Carson-Tahoe Hospital in Carson City, Nev., looked into the possibility of installing its own PACS system. Increased productivity was the main business goal the hospital hoped a PACS system would meet. Only two of three chosen vendors seriously considered the request to bid because of the small number of films produced by the hospital. After installation, the hospital identified the referring physicians who used the most film and then directed its marketing efforts to them. Lessons learned include the tremendous need for training of staff, referring physicians and radiologists. Expect everyone to be slow the first week the new system is running. Map out all processes to prepare for contingencies. Make plans for archiving and be flexible in assigning tasks--next week things may change. Consider bringing in an outside consultant to measure people's expectations and fears. After nearly a year, neither the technologists nor physicians express any regrets about the installation of PACS at Carson-Tahoe.

The biological significance of plasmalogens in defense against oxidative damage

The phospholipid class of plasmalogens is ubiquitously found in considerable amounts as a constituent of mammalian cell membranes and of plasma lipoproteins. Plasmalogens are more susceptible to oxidative reactions compared to their fatty acid ester analogues, due to the reactivity of their enolether function. Studies on plasmalogen-deficient cell lines lead to the proposal that these ether lipids serve as endogenous antioxidants. No clear conclusions regarding the antioxidative effects of plasmalogens could be drawn from studies in patients of different ages with peroxisomal deficiency disorders. A defective peroxisomal plasmalogen synthesis is not necessarily associated with other defects in the metabolism of peroxisomes, as has been established in a cell line recently. In different mammalian tissues a decrease of plasmalogens with age was described. Moreover, an accumulation of plasmalogen oxidation products was measured in brain of old cattle compared to young ones. In pathologic conditions associated with oxidative stress like in spinal cord ischemia and reperfusion, plasmalogen levels varied inversely according to the oxidative burden. Oxidation products of plasmalogens increased with time of ischemia in infarcted porcine heart tissue. Enrichment of lipoproteins with plasmalogens increased their oxidative resistance, which was diminished in the case of LDL particles in patients with coronary arteriosclerosis. In red cell membranes plasmalogens were reduced with donor age and in hyperlipidemia. Under lipid lowering therapy with lovastatin an increase was observed, indicating a possible antioxidative impact of this treatment. Taken together, there is good evidence that plasmalogens are effective as endogenous antioxidants. However, more experimental approaches not confounded by other lipolytic processes are needed to establish this role of plasmalogens.

Altered expression of microtubule-associated protein 1B in cerebral cortical structures of pentylenetetrazole-treated rats

Using Northern blot, immunoblotting, immunocytochemistry, and in situ hybridization, we show that a single administration of the convulsant pentylenetetrazole leads to robust, long-term changes in microtubule-associated protein 1B and its mRNA, in the adult rat brain. The first increases in MAP1B mRNA were detected at 15 hr following pentylenetetrazole administration in the temporal (Te2) and perirhinal cortex followed by increases in microtubule-associated protein 1B immunoreactivity at 72 hr postseizure. In contrast, the levels of microtubule-associated protein 1B mRNA and protein in layers I-II of the retrosplenial and parietal cortex (Par2) declined visibly by 24 hr and 72 h, respectively, post-seizure. The changes included loss of staining in layers I-II and development of structures resembling "strings-of-beads" along the fibers of projection neurons of layer V. The levels of microtubule-associated protein 1B mRNA in the entorhinal cortex peaked at later times (72 h), especially in layers II-III, and returned to control levels by 10 days. Whereas the levels of microtubule-associated protein 1B immunoreactivity in the retrosplenial and parietal cortex recovered by 5-10 days, it persisted at high levels through day 35 in layer V of the temporal cortex (Te2), layers II-III of the perirhinal cortex and layers I-II of the lateral entorhinal cortex. These results indicate that seizure activity leads to long-term upregulation of genes coding for structural elements that are characteristic of the immature brain such as microtubule-associated protein 1B.

Ageing of equine articular cartilage: structure and composition of aggrecan and decorin

In order to identify the pathological processes involved in the destruction of articular cartilage in arthritic diseases, it is first necessary to characterise the normal homeostasis of cartilage in a healthy joint. In particular, normal age-related changes in the biochemistry of cartilage complicate any comparisons that are made between diseased and healthy tissue. There are, however, no reports in the literature detailing the influence of ageing on the biochemistry of proteoglycans in equine articular cartilage. This study addresses the absence of such information by investigating the structure of aggrecan and decorin extracted from a wide age-range of full thickness equine tissue. The total glycosaminoglycan content of articular cartilage from the metacarpophalangeal joint remained relatively constant throughout life. In contrast, specific components such as hyaluronan increased in concentration with advancing age as did the content of a structural epitope present on keratan sulphate chains. There were also significant age-related changes in the sulphation pattern of chondroitin sulphate chains. The structure of the large aggregating proteoglycan (aggrecan) became more heterogeneous in size with increasing age and each of the subspecies of aggrecan identified in the extracts was shown to carry a hyaluronan binding region (G1) domain. All subspecies of aggrecan also expressed specific epitopes to keratan sulphate, chondroitin-4-sulphate and chondroitin-6-sulphate glycosaminoglycan chains. The structure of the small nonaggregating proteoglycan decorin and the aggrecan stabilising molecule link protein were demonstrated to be similar in size and charge to that reported for other species.

In vitro antifungal activity of CAN-296: a naturally occurring complex carbohydrate

The in vitro activity of a naturally occurring complex carbohydrate, CAN-296, was evaluated by testing 132 clinical and ATCC isolates of yeast and Aspergillus fumigatus, many of which were azole-resistant. The in vitro susceptibility tests were performed by standardized broth micro- and macrodilution methods and results were compared with those obtained for amphotericin B, fluconazole, ketoconazole, flucytosine and the pneumocandin L-733,560. All tested Candida species showed highly uniform susceptibility to CAN-296 at concentrations of 0.078 to 0.312 microgram/ml; non-albicans Candida were as susceptible to CAN-296 as the Candida albicans strains. Multi-azole-resistant Candida species were highly sensitive to CAN-296. Minimum inhibitory concentration measurements did not differ from minimum lethal concentrations by more than two-fold for all tested Candida species. Aspergillus fumigatus, on the other hand, showed only moderate susceptibility to CAN-296. The kinetics of the anti-Candida activity of CAN-296 was investigated by kill-curve experiments using C. albicans and C. glabrata and the results were compared with those obtain for amphotericin B. CAN-296 was found to be rapidly fungicidal in concentrations ranging from 4-16 fold the mean MIC value. The broad spectrum of anti-Candida activity together with the rapid fungicidal effect make this complex carbohydrate a promising agent for clinical use.

Increased expression of microtubule-associated protein 1B in the hippocampus, subiculum, and perforant path of rats treated with a high dose of pentylenetetrazole

A single administration of the convulsant pentylenetetrazole (PTZ) initiates a complex pattern of long-term changes in microtubule-associated protein 1B (MAP1B) expression across the hippocampal formation. Using Northern blot and in situ hybridization we show that the first increases in MAP1B mRNA were detected at 15 h following PTZ administration in the granule cells of the dentate gyrus and CA3 region of the hippocampus and reached a maximum at 44 h. The levels of MAP1B mRNA in the subiculum peaked at later times (5 days). At 72 h MAP1B immunoreactivity was mainly localized in the granule-cell bodies and dentate inner and midmolecular layer as well as in neuronal cell bodies and the stratum lucidum, including the mossy fiber pathway of the CA3 region. By 5-10 days the levels of MAP1B in the pyramidal cells in the CA3 region decreased to very low levels; rather, heavy staining of interneuron-like cells and "strings-of-bead" structures all over the hippocampus and at the stratum oriens/alveus border were seen. The levels of MAP1B in the hippocampus returned to control levels by 20 days after PTZ administration. MAP1B immunoreactivity in the alvear path was also evident at 5 days postinjection at the CA1/alveus border. The intensity of MAP1B staining increased gradually in the perforant path starting at 72 h and persisted at high levels until day 35. Our studies show that (i) MAP1B is a temporal and regional marker for rapid and acute epileptic seizures and (ii) long-term increases in MAP1B in the perforant path might play a role in PTZ-induced seizures.

IL-1 beta induces the degradation of equine articular cartilage by a mechanism that is not mediated by nitric oxide

Proteoglycan degradation was induced in young equine articular cartilage explants cultured for eight days in the presence of 50 ng/ml recombinant human interleukin-1 beta. Degradation was initiated after 6 hours of exposure to the cytokine. This was accompanied by an induction of nitric oxide synthesis and a decrease in the incorporation of [36S]sulphate into the glycosaminoglycan chains of proteoglycans. The addition of 1mM N-iminoethyl-L-ornithine (an inhibitor of nitric oxide synthase) to the explant cultures in the presence of rhIL-1 beta suppressed the synthesis of NO and restored proteoglycan synthesis to control levels. However, treatment of explants with LNIO did not overcome proteoglycan degradation. These results indicate that although IL1 beta regulates both proteoglycan synthesis and degradation in equine cartilage explants, only the inhibition of proteoglycan synthesis is mediated by nitric oxide.

Influence of age and treadmill running on motor performance in rats

The influence of treadmill running on age-dependent changes of motor performance was investigated in differently old female Sprague-Dawley rats. Following 12 months of exercise training a test battery including gait analysis, spontaneous motor activity, and three more motor tasks of different complexity was performed. The influence of age on motor performance depended on the complexity of the motor requirement. Simple tests were less affected by age than more complex ones. Treadmill running induced positive effects on the age-dependent impairment of various motor functions in middle-aged (14-18 months old) and aged (23-27 months old) rats. The positive influence of exercise training is explained by benefits of endurance training to the cardiovascular, neuromuscular, and central nervous systems.

The relationship between endothelin-1, event-related P300 potentials, and prognosis in cerebral arteriosclerosis

OBJECTIVES

To search for a potential role of endothelin-1 (ET-1), a potent vasoconstrictor and presumably neurotoxic 21-amino acid peptide, for dysfunction of brain signal processing and cerebrovascular morbidity in nondemented patients with cerebral arteriosclerosis.

DESIGN

Cross-sectional study with longitudinal follow-up.

SETTING

University-affiliated teaching hospital.

PARTICIPANTS

A total of 106 nondemented patients with significant stenosis of either the internal carotid (cAD, cases; n = 63, mean age +/- SD, 62 +/- 7 years) or peripheral arteries (pAD, disease controls; n = 43, 60 +/- 11 years) were investigated before carotid endarterectomy and bypass surgery, respectively. After a mean follow-up of about 19 months, cerebrovascular morbidity of the cAD and pAD patients was evaluated by phone.

MEASUREMENTS

Brain signal processing functions by event-related visual P300 potentials; cerebrovascular events by a structured telephone interview; the extent of arteriosclerosis by venous ET-1 concentration.

RESULTS

Venous ET-1 levels were elevated in both cAD and pAD patient groups, but to the same degree. In these patients, ET-1 concentration was correlated slightly with diastolic blood pressure (r = .334, P = .0326, stepwise regression). Only in cAD patients with ET-1 levels above the 75th percentile were P300 latencies markedly prolonged compared with their lower ET-1 level counterparts. Furthermore, the P300 latencies of the cAD patients, but not of the pAD patients, correlated positively with venous ET-1 concentration and inversely with pack years of smoking (r = .728, P = .0002; stepwise regression). In contrast to base-line P300 abnormalities and classical risk factors (e.g., hypertension), high ET-1 levels predicted an increased cerebrovascular morbidity of cAD, but not of pAD, patients (P = .0044; Mantel Cox test).

CONCLUSIONS

In nondemented patients with cerebral arteriosclerosis, endothelin-1 is associated with P300 abnormalities reflecting subclinical dysfunction of brain signal processing. In the long-term, high venous ET-1 levels also appear to predict a higher cerebrovascular morbidity of cAD patients even after carotid endarterectomy.

Chronic tenosynovitis of the carpal extensor tendon sheaths in 15 horses

The history, clinical features, radiological findings, treatment and outcome of 15 horses with chronic tenosynovitis of the carpal extensor tendon sheaths are reported. The condition was seen most commonly in horses used for jumping and penetration of the tendon sheaths by thorns was the most common aetiology. Treatment involved surgical resection of the hyperplastic synovial membrane, and adhesions within the tendon sheath, with primary closure. When combined with early postoperative physiotherapy this was found to be an effective method of treatment. All horses in this series were not lame at follow-up, with 14 horse returning to their former level of athletic performance.

Proteoglycan metabolism of equine articular chondrocytes cultured in alginate beads

Equine chondrocytes were cultured in vitro for 30 days in ionically gelled alginate beads. The alginate polymerises into a stable gel in the presence of divalent cations (calcium), and rapid depolymerisation in the presence of a calcium chelator releases the viable chondrocytes. The chondrocytes maintained a spherical appearance for 30 days in culture, in marked contrast to monolayer cultures, which develop a dedifferentiated fibroblastic morphology. The major proteoglycan molecule produced by the encapsulated chondrocytes was aggrecan, of similar hydrodynamic size to aggrecan molecules present in the matrix of the articular cartilage from which the cells were harvested. Link protein, keratan sulphate and chondroitin sulphate were also synthesised by the chondrocytes, as demonstrated by immunohistochemistry. The proteoglycan secreted by the chondrocytes consisted of at least two pools, one remaining adjacent to the cell and forming a dense, cell-associated matrix, and another migrating more peripherally into the intercellular compartment. Newly synthesised proteoglycans extracted from the pericellular matrix and the intercellular matrix were similar in hydrodynamic size and aggregated in the presence of exogenous hyaluronan.

V+ fibronectin mRNA is increased in the brains of aged rats: effect of food restriction

Food restriction increases life-span in rodents. With regard to the central nervous system, underfeeding has been shown to have beneficial effects on synaptic transmission in old rats. However, the molecular events underlying functional changes in the brains of food-restricted rats are largely unknown. In the present study the levels of fibronectin mRNA containing the alternatively spliced segment V (FN-V+) as well as the levels of FN mRNA containing the alternatively spliced segment EIIIB (FN-EIIIB+), were examined by RNA gel blot hybridization in the brains of 3-day-old, 24-day-old, 10-month-old, 18-month-old, 30-month-old ad libitum (AL) fed, 30-month-old food-restricted (FR), and 35-37-month-old, FR rats. The hybridization signal for the FN-EIIIB+ mRNA was relatively abundant at early postnatal stages but very few transcripts were detected in the brains of adult, AL rats. The transcripts coding for FN-V+ mRNA were moderately expressed in the brains of 3-day-old, 24-day-old, 10-month-old, and 18-month-old rats. However, the FN-V+ mRNA signal was then prominently increased (approx. 3-fold) in the brains of the 30-month-old, AL rats vs. 10-month-old, AL rats, and further increased (approx. 2-fold) in the brains of 30-month-old, FR, as compared to 30-month-old, AL rats. However, the levels of FN-V+ mRNA were slightly decreased in the brains of very old (35-37-month) FR rats vs. 30-month-old FR rats. The distribution of fibronectin messenger RNA and protein was also investigated by non-radioactive in situ hybridization and immunohistochemistry, respectively. The most prominent expression of FN-V+ messenger RNA was seen in neurons of the hippocampus, including the granule cells of the dentate gyrus, and in layers III and V of the cortex of 30-month-old, FR rats. FN immunostaining closely paralleled the distribution of FN mRNA and was confined to the neuronal cell periphery. The upregulation of fibronectin gene expression upon exposure to glucocorticoids is well documented. Prolonged food restriction, acting as a stress factor, combined with decreased plasticity of glucocorticoid regulatory responses in the aged rats could cause an increase in the levels of FN mRNA and protein in the brains of old, FR rats. Since FN has been shown to provide an adhesive substrate for extending neurites, we conclude that food restriction may potentiate synaptic plasticity, via glucocorticoid receptor binding elements of the FN gene, in the brains of old rats.