Mladen Golubic

The GTPase stimulatory activities of the neurofibromatosis type 1 and the yeast IRA2 proteins are inhibited by arachidonic acid.

Three proteins, GTPase activating protein (GAP), neurofibromatosis 1 (NF1) and the yeast inhibitory regulator of the RAS‐cAMP pathway (IRA2), have the ability to stimulate the GTPase activity of Ras proteins from higher animals or yeast. Previous studies indicate that certain lipids are able to inhibit this activity associated with the mammalian GAP protein. Inhibition of GAP would be expected to biologically activate Ras protein. In these studies arachidonic acid is shown also to inhibit the activity of the catalytic fragments of the other two proteins, mammalian NF1 and the yeast IRA2 proteins. In addition, phosphatidic acid (containing arachidonic and stearic acid) was inhibitory for the catalytic fragment of NF1 protein, but did not inhibit the catalytic fragments of GAP or IRA2 proteins. These observations emphasize the biochemical similarity of these proteins and provide support for the suggestion that lipids might play an important role in their biological control, and therefore also in the control of Ras activity and cellular proliferation.

Reduced expression of schwannomin/merlin in human sporadic meningiomas.

OBJECTIVE:The neurofibromatosis type 2 gene is frequently mutated in sporadic meningiomas. The protein product of the neurofibromatosis type 2 gene is called schwannomin or merlin. Its expression in leptomeningeal cells from which meningiomas are derived and the characteristics of mutated forms in m

Trans-species evolution of Mhc-DRB haplotype polymorphism in primates: Organization of DRB genes in the chimpanzee

The DRB region of the human major histocompatibility complex displays length polymorphism: Five major haplotypes differing in the number and type of genes they contain have been identified, each at appreciable frequency. In an attempt to determine whether this haplotype polymorphism, like the allelic polymorphism, predates the divergence of humansfrom great apes, we have worked out the organization of the DRB region of the chimpanzee Hugo using a combination of chromosome walking, pulsed-field gel electrophoresis, and sequencing. Hugo is a DRB homozygote whose single DRB haplotype is some 440 kilobases (kb) long and contains five genes. At least one and possibly two of these are pseudogenes, while three are presumably active genes. The genes are designated DRB*A0201, DRB2*0101, DRB3*0201, DRB6*0105, and DRB5*0301, and are arranged in this order on the chromosome. The DRB2 and DRB3 genes are separated by approximately 250 kb of sequence that does not seem to contain any additional DRB genes. The DRB*A0201 gene is related to the DRB1 gene of the human DR2 haplotype; the DRB2*0101 and DRB3*0201 genes are related to the DRB2 and DRB3 genes of the human DR3 haplotype, respectively; the DRB6*0105 and DRB5*0301 genes are related to the DRBVI and DRB5 genes of the human DR2 haplotype, respectively. Thus the Hugo haplotype appears to correspond to the entire human DR2 haplotype, into which a region representing a portion of the human DR3 haplotype has been inserted. Since other chimpanzees have their DRB regions organized in different ways, we conclude that, first, the chimpanzee DRB region, like the human DRB region, displays length polymorphism; second, some chimpanzee DRB haplotypes are longer than the longest known human DRB haplotypes; third, in some chimpanzee haplotypes at least, the DRB genes occur in combinations different from those of the human haplotypes; fourth, and most importantly, certain DRB gene combinations have been conserved in the evolution of chimpanzees and humans from their common ancestors. These data thus provide evidence that not only allelic but also haplotype polymorphism can be passed on from one species to another in a given evolutionary lineage.

Major Cereal Grain Fibers and Psyllium in Relation to Cardiovascular Health

Numerous studies reveal the cardiovascular benefits of consuming dietary fiber and, especially, cereal fiber. Cereal fiber is associated with cardiovascular risk reduction through multiple mechanisms and consuming a variety of cereal fiber sources offers health benefits specific to the source. Certain cereal fibers have been studied more extensively than others and provide greater support for their incorporation into a healthful diet. β-glucan from oats or barley, or a combination of whole oats and barley, and soluble fiber from psyllium reduces the risk of coronary heart disease; inulin-type fructans added to foods and beverages may modestly decrease serum triacylglycerols; arabinoxylan and resistant starch may improve glycemic control. Individuals with low cereal fiber intake should increase their intake of whole grains in order to receive the benefits of whole grains in addition to fiber. For those adjusting to the texture and palatability of whole grains, turning to added-fiber products rich in β-glucan and psyllium may allow them to reach their fiber goals without increasing caloric intake.

Conservative evolution of the Mbc-DP region in anthropoid primates

To determine the organization of the DP region in the Mbc of anthropoid primates, we constructed contig maps from cosmid clones of the chimpanzee and orangutan, representatives of the infraorder Catarrhini, as well as of the cotton-top tamarin, a representative of the infraorder Platyrrhini. We found the maps to be remarkably similar to each other and to the previously published map of the human DP region. In each of the four species, the DP region consists of four loci arranged in the same order (DPB2 . . . DPA2 . . . DPB1 . . . DPA1) and in the same transcriptional orientation (tail-to-tail). The regions in the four species are of approximately the same length and many of the restriction sites are shared between species. The inserts of most Alu elements, of a ribosomal protein pseudogene, and of an IgC epsilon-like pseudogene are found in corresponding positions in all four species. The data indicate that the human-type organization of the DP region was established before the divergence of the Catarrhini and Platyrrhini lines more than 37 million years ago and that it has remained principally intact since that time. This conservation of the DP region is in striking contrast to the evolutionary instability of certain other Mbc regions, in particular those occupied by the DRB or C4 and CYP21 loci. We interpret the stability of the DP region as an indication that the region is being phased out functionally.

Multiplication of Mhc-DRB5 loci in the orangutan: implications for the evolution of DRB haplotypes

The β chain-encoding (B) class II genes of the primate major histocompatibility complex belong to several families. The DRB family of class II genes is distinguished by the occurrence of haplotype polymorphism—the existence of multiple chromosomal forms differing in length, gene number, and gene combinations, each form occurring at an appreciable frequency in the population. Some of the haplotypes, or fragments thereof, are shared by humans, chimpanzees, and gorillas. In an effort to follow the DRB haplotype polymorphism further back in time, we constructed DRB contig maps of the two chromosomes present in the orangutan cell line CP81. Two types of genes were found in the two haplotypes, Popy-DRB5 and Popy-DRB1*03, the former occurring in two copies and one gene fragment in each haplotype, so that the CP81 cell line contains four complete DRB5 genes and two DRB5 fragments altogether. Since the four genes are more closely related to one another than they are to other DRB5 genes, they must have arisen from a single ancestral copy by multiple duplications. At the same time, however, the two CP81 haplotypes differ considerably in their restriction enzyme sites and in the presence of Alu elements at different positions, indicating that they have been separated for a length of time that exceeds the lifespan of a primate species. Moreover, a segment of about 100 kilobase pairs is shared between the orangutan CP81-1 and the human HLA-DR2 haplotype. These findings indicate that part of the haplotype polymorphism may have persisted for more than 13 million years, which is the estimated time of human-orangutan divergence.

Increased expression of 5-lipoxygenase in high-grade astrocytomas

OBJECTIVE: 5-Lipoxygenase (5-LO) oxidizes arachidonic acid into proinflammatory eicosanoids that may promote tumorigenesis. In this study, we investigated whether 5-LO is expressed in human astrocytomas and what effect its expression may have on patient outcome. METHODS: Increased 5-LO messenger ribonucleic acid and protein expression was detected by the polymerase chain reaction and antibody-based approaches, respectively, in surgical astrocytoma specimens and established glioblastoma multiforme cell lines compared with primary cell culture from the human white matter. RESULTS: Immunohistochemical analysis revealed predominantly nuclear 5-LO staining in 44 of 49 glioblastoma multiforme samples (90%), 8 of 10 (80%) anaplastic astrocytomas samples, and 3 of 13 (23%) low-grade astrocytoma samples analyzed. Double-staining experiments with anti-CD-68 (macrophage/microglial marker) and anti-5-LO antibodies suggest that both CD-68-positive and CD-68-negative tumor cells express 5-LO protein. Staining of 5-LO was significantly more frequent in high-grade than in low-grade tumors (P = 0.001). Patients whose tumors expressed 5-LO were significantly older, had lower preoperative Karnofsky performance scores and shorter survival than patients whose tumors did not express 5-LO. After adjusting for pathological diagnosis and age, respectively, neither Karnofsky performance score nor survival were significantly associated with 5-LO staining. CONCLUSION: These data indicate that 5-LO is overexpressed in high-grade astrocytomas and supports the idea that eicosanoids may play a role in tumorigenesis of these brain tumors.

Yoga in the Management of Overweight and Obesity

Although yoga may help manage conditions comorbid with overweight and obesity, such as low back pain, whether yoga helps with weight loss or maintenance beyond that which can be achieved with diet and exercise remains unclear. A search of multiple databases through September 2012 was undertaken identifying peer-reviewed studies on yoga, meditation, mindfulness, obesity, and overweight. Studies on yoga and weight loss are challenged by small sample sizes, short durations, and lack of control groups. In addition, there is little consistency in terms of duration of formal group yoga practice sessions, duration of informal practices at home, and frequency of both. Studies do however suggest that yoga may be associated with weight loss or maintenance. Mechanisms by which yoga may assist with weight loss or maintenance include the following: (a) energy expenditure during yoga sessions; (b) allowing for additional exercise outside yoga sessions by reducing back and joint pain; (c) heightening mindfulness, improving mood, and reducing stress, which may help reduce food intake; and (d) allowing individuals to feel more connected to their bodies, leading to enhanced awareness of satiety and the discomfort of overeating. Thus, yoga appears promising as a way to assist with behavioral change, weight loss, and maintenance.

Docosahexaenoic Acid, Inflammation, and Bacterial Dysbiosis in Relation to Periodontal Disease, Inflammatory Bowel Disease, and the Metabolic Syndrome

Docosahexaenoic acid (DHA), a long-chain omega-3 polyunsaturated fatty acid, has been used to treat a range of different conditions, including periodontal disease (PD) and inflammatory bowel disease (IBD). That DHA helps with these oral and gastrointestinal diseases in which inflammation and bacterial dysbiosis play key roles, raises the question of whether DHA may assist in the prevention or treatment of other inflammatory conditions, such as the metabolic syndrome, which have also been linked with inflammation and alterations in normal host microbial populations. Here we review established and investigated associations between DHA, PD, and IBD. We conclude that by beneficially altering cytokine production and macrophage recruitment, the composition of intestinal microbiota and intestinal integrity, lipopolysaccharide- and adipose-induced inflammation, and insulin signaling, DHA may be a key tool in the prevention of metabolic syndrome.

Restriction Fragment Length Polymorphism of C4 Genes in Mice with t Chromosomes

Genomic DNA was isolated from 29 t strains and 4 congenic lines of mice, digested with restriction endonucleases, and hybridized with a probe representing the complement component 4 (C4) gene. All but one of the enzymes revealed restriction fragment length polymorphism in this sample of C4-related genes. Double digestion analysis suggested the presence of three C4 gene copies in some of the t chromosomes and two copies in others. The enzymes distinguished 16 different haplotypes among the 33 strains tested. Based on their restriction fragment length patterns, the t strains could be divided into four groups with strains in each group more closely related to each other with respect to their C4-region genes than strains belonging to different groups. At least three of these four groups represent different branches of the evolutionary tree constructed for the t chromosomes. The C4-related genes of the chromosomes are in strong linkage disequilibrium with the class II genes of the H-2 complex. Typing for the Ss and Slp allotypes of C4 has revealed the presence of the Ss1 phenotype in two t strains and of the Slpa phenotype in one strain.