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Background: Racial differences in the predilection to salt sensitivity may arise from different renal growth patterns. To test this idea, we monitored age-dependent telomere attrition rate, reflecting largely the replicative history of somatic cells, in the outer renal cortex and the inner renal medulla of African Americans and Caucasians. Methods: Telomere length, determined by the mean length of the terminal restriction fragments (TRF), was measured in specimens from 58 African-American and 63 Caucasian males, ages 1 day to 71 years. Results: In the outer renal cortex, TRF length attrition rate was significantly slower in African Americans (–0.021 ± 0.0064 kb/year) than in Caucasians (–0.060 ± 0.0094 kb/year) (p = 0.0007). In both ethnic groups the TRF length attrition rate was slower in the inner medulla than in the outer renal cortex, but without significant racial differences. Conclusions: The proximal tubule is the most abundant nephron structure in the outer renal cortex. Less proliferative growth of proximal tubular cells in kidneys from African Americans may be one factor explaining the slower age-dependent telomere attrition rate in the outer renal cortex of African Americans than in Caucasians. Copyright © 2004 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The article presents an abstract of the study "Effect of Large Neutral Amino Acids and Analogues on the Amino Acid Content in the Extracellular Space of the Rat Hippocampus." The study reports that elevation of any of the large neutral amino acid (LNAA) in the extracellular space will result in an exchange of LNAA out of neuronal cells. The research paper would be presented in the 30th Annual Meeting of the American Society for Neurochemistry, on March 14-17, 1999, in New Orleans, Louisiana.

The article presents an abstract of the paper "Role of Glutamine Hydrolysis in Formation of Extracellular Glutamate in the Rat Hippocampus," which will be presented at the 30th Annual Meeting of the American Society for Neurochemistry to be held in New Orleans, Louisiana from March 14-17, 1999. The paper suggests that increased extracellular concentration of glutamate increases after pyramidal cell damage produced by the injection of quinolinic acid.

Introduction/Objective Although the Internet, podcasts and multimedia have become a natural part of our life, these instruments still do not find widespread use in medical education. We aimed to increase the percentage of students benefiting from our lectures during their 6-month principal training period in dermatology by making lectures available online. Methods To establish a baseline, we started to count and calculate the average percentage of students attending face to face classes. For the next semester, with a new student generation, we made recordings of about half of the lectures and made them available online. After this testing period, we informed the next new student population at the beginning of the following semester that all lectures would be recorded and made available online. Students’ attendance was documented during these periods, and in addition, questionnaires were used to assess students’ acceptance and use of the online lectures. Results At the end of the project, 66% of the students ( n = 256) indicated that they had used the online lectures, and 12% of all students stated that they were usually unable to attend lectures due to conflicting obligations, but could now participate thanks to the e-learning programme. An additional 44.9% of all respondents indicated that they welcomed the e-learning programme as a way to view specific lectures. The average attendance of face-to-face lectures did not decrease. Conclusion Online lectures in dermatology were highly welcomed by our students and may be a good means to improve the education of students in dermatology. Conflicts of interest None declared. [ABSTRACT FROM AUTHOR]

Gene expression profiles were assessed in the hippocampus, ento-rhinal cortex, superior-frontal gyrus, and postcentral gyrus across the lifespan of 55 cognitively intact individuals aged 20-99 years. Perspectives on global gene changes that are associated with brain aging emerged, revealing two overarching concepts. First, different regions of the forebrain exhibited substantially different gene profile changes with age. For example, comparing equally powered groups, 5,029 probe sets were significantly altered with age in the superior-frontal gyrus, compared with 1,110 in the entorhinal cortex. Prominent change occurred in the sixth to seventh decades across cortical regions, suggesting that this period is a critical transition point in brain aging, particularly in males. Second, clear gender differences in brain aging were evident, suggesting that the brain undergoes sexually dimorphic changes in gene expression not only in development but also in later life. Globally across all brain regions, males showed more gene change than females. Further, Gene Ontology analysis revealed that different categories of genes were predominantly affected in males vs. females. Notably, the male brain was characterized by global decreased catabolic and anabolic capacity with aging, with down-regulated genes heavily enriched in energy production and protein synthesis/transport categories. Increased immune activation was a prominent feature of aging in both sexes, with proportionally greater activation in the female brain. These data open opportunities to explore age-dependent changes in gene expression that set the balance between neurodegeneration and compensatory mechanisms in the brain and suggest that this balance is set differently in males and females, an intriguing idea. [ABSTRACT FROM AUTHOR]

Several lines of work have shown that astrocytes release glutamate in response to receptor activation, which results in a modulation of local synaptic activity. Astrocytic glutamate release is Ca2+-dependent and occurs in conjunction with exocytosis of glutamate containing vesicles. However, astrocytes contain a millimolar concentration of cytosolic glutamate and express channels permeable to small anions, such as glutamate. Here, we tested the idea that astrocytes respond to receptor stimulation by dynamic changes in cell volume, resulting in volume-sensitive channel activation, and efflux of cytosolic glutamate. Confocal imaging and whole-cell recordings demonstrated that astrocytes exhibited a transient Ca2+-dependent cell volume increase, which activated glutamate permeable channels. HPLC analysis revealed that glutamate was released in conjunction with other amino acid osmolytes. Our observations indicate that volume-sensitive channel may constitute a previously uncharacterized target for modulation of astrocyte-neuronal interactions. [ABSTRACT FROM AUTHOR]

Objectives. Recurrent hypoxemia has been proposed as an important pathophysiological mechanism underlying sudden infant death syndrome (SIDS). However, conflicting results emerged when xanthines were used as markers for hypoxia. The vascular endothelial growth factor (VEGF) gene is highly sensitive to changes in tissue partial oxygen tension, and changes in genomic and protein expression occur even after changes in oxygenation within the physiologic range. Methods. For determining whether hypoxia precedes SIDS, VEGF levels were measured using an enzyme-linked immunosorbent assay in the cerebrospinal fluid (CSF) of 51 SIDS infants and in 33 additional control infants who died of an identifiable cause. In addition, 6 rats that had a chronically implanted catheter in the lateral ventricle were exposed to a short hypoxic challenge, and VEGF concentrations were measured in CSF at various time points for 24 hours. Another set of 6 rats were killed with a pentobarbital overdose, and VEGF CSF levels were obtained at different time points after death. Results. Mean VEGF concentrations in CSF were 308.2 ± 299.1 pg/dL in the SIDS group and 85.1 ± 82.9 pg/dL in those who died of known causes. Mean postmortem delay averaged 22 hours for both groups. In rat experiments, hypoxic exposures induced time-dependent increases in VEGF, peaking at 12 hours and returning to baseline at 24 hours. Postmortem duration in the animals was associated with gradual increases in VEGF that reached significance only at 36 hours. Conclusions. We conclude that VEGF CSF concentrations are significantly higher in infants who die of SIDS. We postulate that hypoxia is a frequent event that precedes the sudden and unexpected death of these infants. [ABSTRACT FROM AUTHOR]

Brain biospecimen banking requires centralized resources, national networks for referral of donors, trained personnel to interact with grieving families, and scientific staff to process the biospecimens. Process development of quality control standards is needed to meet the specific requirements of emerging genomic and proteomic technologies. Attention has to be paid to agonal factors and postmortem interval, tissue processing, neuropathology review, and long-term storage. Samples of both diseased and unaffected normal tissues are required with age- and gender-matched control tissues. Data management is vital to store and retrieve quality control measures, clinical and pathologic data linked to the biospecimens. Customized solutions for managing the acquisition and long-term storage of high-quality brain and tissue biospecimens is necessary to support neuroscience research programs, biomarker discovery and genome scale technologies. Biorepositories that operate according to best-practice policies and procedures guarantee the final wish of the families who donate tissue to support neuroscience research and discovery science., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Elder neglect is the one of the most pervasive forms of mistreatment, and often the only place outside of the individual's residence to identify and assist neglected individuals is in a medical setting. However, elder neglect cases treated in hospitals do not present with a single diagnosis or clinical sign, but rather involve a complex constellation of clinical signs. Currently, there is a lack of comprehensive guidelines on which clinical signs to use in screening tools for neglect among patients treated in hospitals. Using the DELPHI method, a group of experts developed and tested a scale to be used as a pre-screener that conceptually could be integrated into electronic health record systems so that it could identify potential neglect cases in an automated manner. By applying the scale as a pre-screener for neglect, the tool would reduce the pool of at-risk patients who would benefit from in-depth screening for elder neglect by 95%.

Solid tissues are critical for child-health research. Specimens are commonly obtained at the time of biopsy/surgery or postmortem. Research tissues can also be obtained at the time of organ retrieval for donation or from tissue that would otherwise have been discarded. Navigating the ethics of solid tissue collection from children is challenging, and optimal handling practices are imperative to maximize tissue quality. Fresh biopsy/surgical specimens can be affected by a variety of factors, including age, gender, BMI, relative humidity, freeze/thaw steps, and tissue fixation solutions. Postmortem tissues are also vulnerable to agonal factors, body storage temperature, and postmortem intervals. Nonoptimal tissue handling practices result in nucleotide degradation, decreased protein stability, artificial posttranslational protein modifications, and altered lipid concentrations. Tissue pH and tryptophan levels are 2 methods to judge the quality of solid tissue collected for research purposes; however, the RNA integrity number, together with analyses of housekeeping genes, is the new standard. A comprehensive clinical data set accompanying all tissue samples is imperative. In this review, we examined: the ethical standards relating to solid tissue procurement from children; potential sources of solid tissues; optimal practices for solid tissue processing, handling, and storage; and reliable markers of solid tissue quality., (Copyright © 2016 by the American Academy of Pediatrics.)

Epilepsy is a common chronic neurological disorder characterized by seizures. Mortality is significantly increased in patients with epilepsy. Sudden unexpected death in epilepsy (SUDEP) is the most common seizure-related category of death. A retrospective study of forensic autopsy cases from 2007 to 2009 at the Office of the Chief Medical Examiner (OCME) yielded a total of 104 sudden unexpected deaths directly or indirectly caused by an epilepsy/seizure disorder in the State of Maryland. Of these deaths, 74 cases met a general accepted definition of SUDEP. The age of SUDEP individuals ranged from 14 to 63 with the majority of subjects in the ages between 21 and 50 years (58 cases, 78.4%). Males were slightly more likely than females to die of SUDEP (male:female=1.5:1 based on the rate). The onset age of epilepsy was documented in 47.3% of cases (35/74) based on investigation and medical records. Of the 35 cases, 12 subjects had early onset epilepsy (onset ages 1-15 years) and 20 subjects had duration of epilepsy for more than 10 years. The majority of deaths (61 of the 74 cases, 82.4%) were unwitnessed. Death scene investigation showed that 71 deaths (95.9%) occurred inside their residence with 50 subjects (70.4%) found either in bed or on the bedroom floor near the bed. Forty-three out of 74 cases (58.1%) showed neuropathological lesions. Per history, 50 subjects were reported as being on anti-epileptic drugs (AEDs). However, postmortem toxicological analysis revealed that only 26 subjects (35.1%) had detectable AEDs. Of the 74 cases, seizure disorder or epilepsy was listed as primary cause of death in 66 cases and the term of SUDEP as official cause of death in only 8 cases. This report focuses on the characteristics of death scene investigation and postmortem examination findings of SUDEP cases., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Effect-directed analysis (EDA) can be useful in identifying and evaluating potential toxic chemicals in matrixes. Previous investigations of extracts of sediments from the upper Danube River in Germany revealed acute nonspecific and mechanism-specific toxicity as determined by several bioassays. In the present study, EDA was used to further characterize these sediments and identify groups of potentially toxic chemicals. Four extracts of sediments were subjected to a novel fractionation scheme coupled with identification of chemicals to characterize their ability to disrupt steroidogenesis or cause mutagenic and/or teratogenic effects. All four whole extracts of sediment caused significant alteration of steroidogenesis and were mutagenic as well as teratogenic. The whole extracts of sediments were separated into 18 fractions and these fractions were then subjected to the same bioassays as the whole extracts. Fractions 7 to 15 of all four extracts were consistently more potent in both the Ames fluctuation and H295R assays. Much of this toxicity could be attributed to polycyclic aromatic hydrocarbons, sterols, and in fraction 7-naphthoic acids. Because the fraction containing polychlorinated biphenyls, polychlorodibenzodioxin/furan, dichlorodiphenyltrichloroethane, and several organophosphates did not cause any observable effects on hormone production or a mutagenic response, or were not detected in any of the samples, these compounds could be eliminated as causative agents for the observed effects. These results demonstrate the value of using EDA, which uses multiple bioassays and new fractionation techniques to assess toxicity. Furthermore, to our knowledge this is the first study using the recently developed H295R assay within EDA strategies., (Copyright © 2012 SETAC.)

Inflammatory myofibroblastic tumor (IMT) or inflammatory pseudotumor is a rare primary cardiac tumor that may result in sudden death. We report a sudden unexpected death due to occlusion of the coronary arteries by IMT arising from the left coronary cusp of the aortic valve. An 8-year-old child suddenly woke up from his sleep with complaint of severe chest pain to his parents, and shortly he became unresponsive. He expired 40 min later in the hospital despite resuscitation efforts. The postmortem examination revealed a 2.5 × 2 × 1-cm mass composed of multiple entangled slender cylindrical fronts, filling the coronary sinus and obstructing the coronary ostia. The patient had complained of recurrent chest pains about 2 weeks prior to his death. Echocardiogram was conducted on the patient but did not recognize the mass. Histological examination of the mass established the diagnosis of primary cardiac IMT. The detailed pathological findings are described. In addition, the literature is reviewed, and pathogenesis, clinical presentation, and the importance of forensic autopsy examination are discussed.

This review summarizes microdialysis studies that address the question of which compounds serve as energy sources in the brain. Microdialysis was used to introduce 14C-labeled glucose, lactate, pyruvate, glutamate, glutamine, and acetate into the interstitial fluid of the brain to observe their metabolism to 14CO2. Although glucose uptake from the systemic system supplies the carbon source for these compounds, compounds synthesized from glucose by the brain are subject to recycling including complete metabolism to CO2. Therefore, the brain utilizes multiple compounds in its domain to provide the energy needed to fulfill its function. The physiological conditions controlling metabolism and the contribution of compartmentation into different brain regions, cell types, and subcellular spaces are still unresolved. The aconitase inhibitor fluorocitrate, with a lower inhibition threshold in glial cells, was used to identify the proportion of lactate and glucose that was oxidized in glial cells versus neurons. The fluorocitrate data suggest that glial and neuronal cells are capable of utilizing both lactate and glucose for energy metabolism.

Background: Numerous e-learning initiatives have been launched during the last decade. Many of them have not been continued, due to lack of acceptance on the part of the students, low quality or insufficient financial funding. Since 2002, the DEJAVU project has been integrated into the curriculum at the Department of Dermatology at Charité-Universitätsmedizin Berlin. DEJAVU offers an online archive of recorded lectures, lecture hand outs, structured learning modules, and case reports as well as online information about the courses/classes., Methods: Since beginning of the summer semester 2005, the student's acceptance and utilization of the online offerings was regularly surveyed, using anonymous questionnaires handed out together with the final exams. The teaching staff's opinions about e-learning were surveyed by means of a single anonymous questionnaire., Results: At the end of winter semester 2006/2007, 93.5% of the students were aware of the existence of the e-learning program. The average amount of time spent with the program was 14.7 hours over the course of one semester. 66.8% of the students considered the program as very useful for their dermatology training. The lecture notes were the most frequently used online resource. Among the teaching staff, 86% considered e-learning a useful addition to traditional teaching., Conclusions: Our results show that e-learning is very well accepted by our students. It offers an additional way of acquiring knowledge and should be used to complement traditional ways of teaching.

Background: Injectable fillers are widely used in aesthetic medicine. Although most materials are considered to be safe, adverse events occur. Our knowledge on frequency and potential risk factors is limited., Objective: The aim of this study was to describe adverse reactions to injectable fillers based on a partly population-based case series., Methods: Dermatologists, plastic surgeons, and maxillofacial surgeons in Berlin were asked to report patients with adverse reactions. Additional patients were obtained from a private practice. A standardized questionnaire was used to assess all data. All data were analyzed by descriptive measures., Results: Fifty-six patients (age, 48+/-11.2 (SD) years) who had been treated with nine different fillers were assessed. In 48 patients treated with only one filler, 167 areas had been treated. In 129 (77.3%) areas adverse reactions occurred 12.2+/-15.6 (SD) months after injection. Adverse reactions to biodegradable fillers occurred after 4.9+/-5.8 (SD) months, and reactions to nonbiodegradable fillers after 18.3+/-19.0 (SD) months (p=.005). As adverse events, continuing pain, swelling, nodules, pigmentation, abscess formation, and erythema were found., Conclusion: Adverse reactions can be documented for all injectable fillers. Time until reaction as well as type of reaction, however, vary between different fillers. Further research is necessary to evaluate potential risk factors.

Hypersynchronous neuronal firing is a hallmark of epilepsy, but the mechanisms underlying simultaneous activation of multiple neurons remains unknown. Epileptic discharges are in part initiated by a local depolarization shift that drives groups of neurons into synchronous bursting. In an attempt to define the cellular basis for hypersynchronous bursting activity, we studied the occurrence of paroxysmal depolarization shifts after suppressing synaptic activity using tetrodotoxin (TTX) and voltage-gated Ca(2+) channel blockers. Here we report that paroxysmal depolarization shifts can be initiated by release of glutamate from extrasynaptic sources or by photolysis of caged Ca(2+) in astrocytes. Two-photon imaging of live exposed cortex showed that several antiepileptic agents, including valproate, gabapentin and phenytoin, reduced the ability of astrocytes to transmit Ca(2+) signaling. Our results show an unanticipated key role for astrocytes in seizure activity. As such, these findings identify astrocytes as a proximal target for the treatment of epileptic disorders.

Elder abuse remains a rapidly growing but largely invisible national policy issue. As the number of elderly persons increases, so will elder abuse, neglect, and financial exploitation. This has implications not only for the victims and the programs struggling to protect them but also for publicly funded programs such as Medicare and Medicaid. The urgent problem is to address elder abuse on a national level in a comprehensive and informed way to prevent the untold suffering of hundreds of thousands of older persons who deserve to live their final years with dignity and security.

It is a major recent finding that astrocytes can influence synaptic activity by release of glutamate, but many other glutamate-mediated activities are also controlled by astrocytes. Even the most obvious neuronal function of glutamate - its release as a transmitter - is regulated by astrocytes; these cells are needed for formation of precursors for glutamate synthesis, for reuptake of released transmitter, and for disposal of excess glutamate. Without astrocytic involvement, normal function of glutamatergic neurons is not possible, as exemplified by almost instantaneous abrogation of normal vision and learning upon inhibition of astrocyte-specific metabolic pathways. In addition, astrocytes are essential for production of the neuroprotectant glutathione, yet they can also contribute to neuronal death during ischemia by maintaining glutamine synthesis, enabling neuronal formation of neurotoxic glutamate.

The MeduMobile project or Mobiler Campus Charité was started in the beginning of 2003 to evaluate new, multimedia supported teaching and learning scenarios. The project focuses especially on acute and rare diseases to which students usually have are very limited access. During the teaching sessions the MeduOnCall team and the academic teacher communicate with the students who are equipped with individual notebooks through a wireless net. In dermatology the MeduMobile project focused in summer 2003 and winter 2003/2004 on bedside teaching. Despite some technical difficulties in the beginning the project was well received by teachers and students. The possibility of simultaneous online searches by Internet as well as the possibility to include photographs depicting the course of the skin disease was felt to be one of the main advantages of this project. Based on these positive experiences an attempt will be made to integrate the project further into the regular teaching of the Charite.

Elimination of glutamate through enzymatic degradation is an alternative to glutamate receptor blockade in preventing excitotoxic neuronal injury. Glutamate pyruvate transaminase (GPT) is a highly active glutamate degrading enzyme that requires pyruvate as a co-substrate. This study examined the ability of GPT to protect neurons of the hippocampal slice preparation against glutamate toxicity. Two methods were used to elevate the concentration of glutamate in the peri-neuronal space. In an endogenous release paradigm, slices were incubated with 100-500 microM L-trans-pyrrolidine-2,4-dicarboxylate (PDC), an inhibitor of glutamate re-uptake. One hour of exposure to PDC in normal, pyruvate-free slice maintenance medium caused a dose dependent increase in neuronal death assessed 24 h later by propidium iodide uptake in dead cell nuclei. GPT (10 U/ml) decreased neuronal death caused by exposure to PDC at all PDC concentrations tested. Neuroprotection in this model was not dependent on added or non-physiologic levels of pyruvate. In a different paradigm, glutamate was added directly to the normal, pyruvate-free slice maintenance medium and not rinsed away, exposing the slices to a range of 1-5 mM glutamate for an extended period. Twenty-four hours later, neuronal death was again assessed by propidium iodide uptake. GPT was again neuroprotective, decreasing neuronal death in the range from 3 to 5 mM glutamate. In the setting of incubation with this large load of glutamate, neuroprotection by GPT was enhanced by adding pyruvate to the medium. GPT is an effective neuroprotectant against glutamate excitotoxicity. When exposure is limited to endogenously released glutamate, neuroprotection by GPT is not dependent on added pyruvate.

In the rodent brain, astrocytes are known to be the primary source of kynurenate (KYNA), an endogenous antagonist of both the glycine(B) and the alpha7 nicotinic acetylcholine receptor. In the present study, primary human astrocytes were used to examine the characteristics and regulation of de novo KYNA synthesis in vitro. To this end, cells were exposed to KYNA's bioprecursor L-kynurenine, and newly formed KYNA was recovered from the extracellular milieu. The production of KYNA was stereospecific and rose with increasing L-kynurenine concentrations, reaching a plateau in the high microM range. In an analogous experiment, astrocytes also readily produced and liberated the potent, specific glycine(B) receptor antagonist 7-chlorokynurenate from L-4-chlorokynurenine. KYNA synthesis was dose-dependently reduced by L-leucine or L-phenylalanine, two amino acids that compete with L-kynurenine for cellular uptake, and by aminooxyacetate, a non-specific aminotransferase inhibitor. In contrast, KYNA formation was stimulated by 5 mM pyruvate or oxaloacetate, which act as co-substrates of the transamination reaction. Aglycemic or depolarizing (50 mM KCl or 100 microM veratridine) conditions had no effect on KYNA synthesis. Subsequent studies using tissue homogenate showed that both known cerebral kynurenine aminotransferases (KAT I and KAT II) are present in astrocytes, but that KAT II appears to be singularly responsible for KYNA formation under physiological conditions. Taken together with previous results, these data suggest that very similar mechanisms control KYNA synthesis in the rodent and in the human brain. These regulatory events are likely to influence the neuromodulatory effects of astrocyte-derived KYNA in the normal and diseased human brain.

The present study determined the metabolic fate of [U-13C]glutamate in primary cultures of cerebral cortical astrocytes from rat brain and also in cultures incubated in the presence of 1 or 5 mM alpha-ketoisocaproate (alpha-KIC). When astrocytes were incubated with 0.2 mM [U-13C]glutamate, 64.1% of the 13C metabolized was converted to glutamine, and the remainder was metabolized via the tricarboxylic acid (TCA) cycle. The formation of [1,2,3-(13)C3]glutamate demonstrated metabolism of the labeled glutamate via the TCA cycle. In control astrocytes, 8.0% of the [13C]glutamate metabolized was incorporated into intracellular aspartate, and 17.2% was incorporated into lactate that was released into the medium. In contrast, there was no detectable incorporation of [13C]glutamate into aspartate in astrocytes incubated in the presence of alpha-KIC. In addition, the intracellular aspartate concentration was decreased 50% in these cells. However, there was increased incorporation of [13C]glutamate into the 1,2,3-(13)C3-isotopomer of lactate in cells incubated in the presence of alpha-KIC versus controls, with formation of lactate accounting for 34.8% of the glutamate metabolized in astrocytes incubated in the presence of alpha-KIC. Altogether more of the [13C]glutamate was metabolized via the TCA cycle, and less was converted to glutamine in astrocytes incubated in the presence of alpha-KIC than in control cells. Overall, the results demonstrate that the presence of alpha-KIC profoundly influences the metabolic disposition of glutamate by astrocytes and leads to altered concentrations of other metabolites, including aspartate, lactate, and leucine. The decrease in formation of aspartate from glutamate and in total concentration of aspartate may impair the activity of the malate-aspartate shuttle and the ability of astrocytes to transfer reducing equivalents into the mitochondria and thus compromise overall energy metabolism in astrocytes.

MMP-2, a secreted 72-kd metalloproteinase that specifically degrades type IV collagen as well as denatured collagens, has been implicated in smooth muscle cell migration. To evaluate the possible contribution of this enzyme to the formation and progression of the atherosclerotic lesion, the expression of MMP-2 was studied in human aortic tissue. MMP-2 was visualized in frozen sections of the aortic wall by an immunofluorescent technique with a polyclonal antibody. Expression of MMP-2 in the aortic extracts was also studied by zymography and Western blotting. Our results reveal that a greater amount of MMP-2 is present in fatty streaks and atherosclerotic plaques as compared with normal regions of the aorta. Immunoblotting analysis showed that MMP-2 was expressed in atherosclerotic plaque > fatty streak > normal aortic wall in a ratio of approximately 4:2:1. Zymograms show that both forms (activated and latent) of MMP-2 increased in the atherosclerotic plaques. The presence of macrophages, detected by an immunohistochemical technique in some areas of higher MMP-2 expression suggests that these cells are a possible source of MMP-2. We conclude that MMP-2 collagenase may have a role in the formation and progression of the atherosclerotic lesion and may be involved in clinical complications of atherosclerosis, such as fissure and rupture, leading to thrombosis.

Upregulation of brain adenosine receptors in DBA/2J mice as affected by theophylline and caffeine, adenosine antagonists, was examined following subcutaneous drug implantation to ensure chronic exposure. Scatchard analysis of binding to membranes of cerebral cortex and cerebellum from individual mice showed a differential upregulation of (-)-N6-R-[G-3H]phenylisopropyladenosine ([3H]-L-PIA) binding density by theophylline. After 14 days of exposure to theophylline (serum concentration of 1.2 +/- 0.01 micrograms/ml measured by HPLC analysis), the Bmax for L-PIA binding to cerebellar membranes increased 22% over the control mice (statistically significant at P less than 0.01 level). Theophylline had no effect on the Bmax for L-PIA binding to cerebral cortical membranes. The observed increases in Bmax values of cerebellar (13.2%) and cerebral cortical membrane binding (14.2%) on chronic exposure to caffeine (7.1 +/- 0.5 micrograms/ml) were not statistically significant at the P less than or equal to 0.05 level. Neither methylxanthine affected the dissociation constant, KD, for L-PIA. The increased potential for adenosine receptor upregulation by theophylline compared to caffeine following chronic, low level exposure suggests that caffeine treatment for sleep apnea may be preferred to the standard theophylline therapy.

Malignant cells have enhanced sensitivity to inhibition of growth by thymidine. Cell growth of the permanent lymphoid cell line CCRF-CEM, originating from a patient with acute lymphoblastic leukemia, is inhibited by 3 x 10(-5) M thymidine, compared to 1 to 5 x 10(-3) M thymidine required to inhibit growth of normal lymphoid lines. Thymidine-resistant cells were isolated at a frequency of approximately 1/100,000 cells after cloning CCRF-CEM cells in medium containing 5 x 10(-4) M thymidine. The resistant cells lacked the enzyme thymidine kinase, had a 20-fold decrease of thymidine uptake, and were resistant to 1 x 10(-4) M 5-bromo-2-deoxyuridine. The cells were sensitive to 1 x 10(-5) M methotrexate, even in the presence of exogenously added thymidine and hypoxanthine. The data indicate that a small fraction of malignant cells may escape the toxic effect of high thymidine therapy and therefore, require additional chemotherapy for their control.