Distinct types of diffuse large B-cell lymphoma identified by gene expression profiling

Diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin's lymphoma, is clinically heterogeneous: 40% of patients respond well to current therapy and have prolonged survival, whereas the remainder succumb to the disease. We proposed that this variability in natural history reflects unrecognized molecular heterogeneity in the tumours. Using DNA microarrays, we have conducted a systematic characterization of gene expression in B-cell malignancies. Here we show that there is diversity in gene expression among the tumours of DLBCL patients, apparently reflecting the variation in tumour proliferation rate, host response and differentiation state of the tumour. We identified two molecularly distinct forms of DLBCL which had gene expression patterns indicative of different stages of B-cell differentiation. One type expressed genes characteristic of germinal centre B cells ('germinal centre B-like DLBCL'); the second type expressed genes normally induced during in vitro activation of peripheral blood B cells ('activated B-like DLBCL'). Patients with germinal centre B-like DLBCL had a significantly better overall survival than those with activated B-like DLBCL. The molecular classification of tumours on the basis of gene expression can thus identify previously undetected and clinically significant subtypes of cancer.

The transcriptional program in the response of human fibroblasts to serum

The temporal program of gene expression during a model physiological response of human cells, the response of fibroblasts to serum, was explored with a complementary DNA microarray representing about 8600 different human genes. Genes could be clustered into groups on the basis of their temporal patterns of expression in this program. Many features of the transcriptional program appeared to be related to the physiology of wound repair, suggesting that fibroblasts play a larger and richer role in this complex multicellular response than had previously been appreciated.

Export of dissolved organic carbon from peatlands under elevated carbon dioxide levels

Peatlands represent a vast store of global carbon. Observations of rapidly rising dissolved organic carbon concentrations in rivers draining peatlands have created concerns that those stores are beginning to destabilize. Three main factors have been put forward as potential causal mechanisms, but it appears that two alternatives--warming and increased river discharge--cannot offer satisfactory explanations. Here we show that the third proposed mechanism, namely shifting trends in the proportion of annual rainfall arriving in summer, is similarly unable to account for the trend. Instead we infer that a previously unrecognized mechanism--carbon dioxide mediated stimulation of primary productivity--is responsible. Under elevated carbon dioxide levels, the proportion of dissolved organic carbon derived from recently assimilated carbon dioxide was ten times higher than that of the control cases. Concentrations of dissolved organic carbon appear far more sensitive to environmental drivers that affect net primary productivity than those affecting decomposition alone.

A physical map of 30,000 human genes

A map of 30,181 human gene-based markers was assembled and integrated with the current genetic map by radiation hybrid mapping. The new gene map contains nearly twice as many genes as the previous release, includes most genes that encode proteins of known function, and is twofold to threefold more accurate than the previous version. A redesigned, more informative and functional World Wide Web site (www.ncbi.nlm.nih.gov/genemap) provides the mapping information and associated data and annotations. This resource constitutes an important infrastructure and tool for the study of complex genetic traits, the positional cloning of disease genes, the cross-referencing of mammalian genomes, and validated human transcribed sequences for large-scale studies of gene expression.

Glial cell line-derived neurotrophic factor reverses toxin-induced injury to midbrain dopaminergic neurons in vivo

Fischer 344 rats were unilaterally injected into the medial forebrain bundle with 6-hydroxydopamine (6-OHDA). Apomorphine-induced rotational behavior was used to select animals whose rotation exceeded 300 turns/h, corresponding to greater than 95% dopamine (DA) depletion in the ipsilateral striatum. Four weeks later, glial cell line-derived neurotrophic factor (GDNF) or vehicle was injected intranigrally ipsilateral to the lesion (0.1-100 micrograms). The highest dose of GDNF tested produced a marked decrease in rotational behavior. This dose also produced levels of DA in the ipsilateral substantia nigra (SN) which were not statistically different from the contralateral side. Vehicle-treated animals showed a marked DA depletion in the ipsilateral SN. These results demonstrate neurochemical and behavioral improvements in unilaterally DA-lesioned rats following intranigral administration of GDNF, suggesting that GDNF may develop into a useful therapy for Parkinson's disease.

Human reserve pluripotent mesenchymal stem cells are present in the connective tissues of skeletal muscle and dermis derived from fetal, adult, and geriatric donors

This study details the profile of 13 cell surface cluster differentiation markers on human reserve stem cells derived from connective tissues. Stem cells were isolated from the connective tissues of dermis and skeletal muscle derived from fetal, mature, and geriatric humans. An insulin/dexamethasone phenotypic bioassay was used to determine the identity of the stem cells from each population. All populations contained lineage-committed myogenic, adipogenic, chondrogenic, and osteogenic progenitor stem cells as well as lineage-uncommitted pluripotent stem cells capable of forming muscle, adipocytes, cartilage, bone, fibroblasts, and endothelial cells. Flow cytometric analysis of adult stem cell populations revealed positive staining for CD34 and CD90 and negative staining for CD3, CD4, CD8, CD11c, CD33, CD36, CD38, CD45, CD117, Glycophorin-A, and HLA DR-II.

p16INK4A and p19ARF act in overlapping pathways in cellular immortalization

The INK4A locus encodes two independent but overlapping genes, p16INK4A and p19ARF, and is frequently inactivated in human cancers. The unusual structure of this locus has lead to ambiguity regarding the biological role of each gene. Here we express, in primary mouse embryonic fibroblasts (MEFs), antisense RNA constructs directed specifically towards either p16INK4A or p19 ARF. Such constructs induce extended lifespan in primary MEFs; this lifespan extension is reversed upon subsequent elimination of the p16INK4A or p19ARF antisense constructs. In immortal derivatives of cell lines expressing antisense p16INK4A or p19ARF RNA, growth arrest induced by recovery of p16INK4A expression is bypassed by compromising the function of the retinoblastoma protein (Rb), whereas growth arrest induced by re-expression of p19ARF is overcome only by simultaneous inactivation of both the Rb and the p53 pathways. Thus, the physically overlapping p16INK4A and p19ARF genes act in partly overlapping pathways.

Glial cell line-derived neurotrophic factor augments midbrain dopaminergic circuits in vivo

Recently, a novel glial cell line-derived neurotrophic factor (GDNF) has been identified, cloned, and shown to have potent survival- and growth-promoting activity on fetal rat midbrain dopaminergic neurons in cell culture. In this study, we document marked and long-lasting effects on adult rat midbrain dopaminergic neurons in vivo after intracranial administration. A single injection of this factor into the substantia nigra elicited a dose-dependent increase in both spontaneous and amphetamine-induced motor activity, and a decrease in food consumption, lasting 7-10 days. Using immunocytochemistry, we found sprouting of tyrosine hydroxylase-positive neurites towards the injection site, and increased tyrosine hydroxylase immunoreactivity of the ipsilateral striatum was produced by GDNF. There was also a marked and dose-dependent increase in dopamine turnover in the substantia nigra and striatum, and in ipsilateral dopamine levels in the substantia nigra. Little or no effects of GDNF were seen on norepinephrine or serotonin levels. The neurochemical changes on dopaminergic afferents persist for at least 3 weeks after a single intracranial injection of 10 micrograms. Taken together, these data suggest that this glial cell line-derived factor has a potent influence on adult rat dopamine neurons and may have a potentially important role as a trophic factor for these neurons.

Osteoblastic gene expression during adipogenesis in hematopoietic supporting murine bone marrow stromal cells

A growing body of data suggests that the bone marrow stroma contains a population of pluripotent cells capable of differentiating into adipocytes, osteoblasts, and lymphohematopoietic supporting cells. In this work, the murine stromal cell lines BMS2 and +/+ 2.4 have been examined as preadipocytes and adipocytes for evidence of osteoblastic gene expression. Adipocyte differentiation has been quantitated using fluorescence activated cell sorting. Within 7-10 days of adipocyte induction by treatment with glucocorticoids, indomethacin, and methylisobutylxanthine, between 40% to 50% of the cells contain lipid vacuoles and exhibit a characteristic adipocyte morphology. Based on immunocytochemistry, both the adipocytes and preadipocytes express a number of osteoblastic markers; these include alkaline phosphatase, osteopontin, collagen (I, III), bone sialoprotein II, and fibronectin. Based on biochemical assays, the level of alkaline phosphatase expression is not significantly different between preadipocyte and adipocyte cells. However, unlike rat cell lines, dexamethasone exposure causes a dose-dependent decrease in enzyme activity. The steady-state mRNA levels of the osteoblast associated genes varies during the process of adiopogenesis. The relative level of collagen I and collagen III mRNA is lower in adipocyte-induced cells when compared to the uninduced controls. Osteocalcin mRNA is detected in preadipocytes but absent in adipocytes. These data indicate that osteoblastic gene expression is detected in cells capable of undergoing adipocyte differentiation, consistent with the hypothesis that these cell lineages are interrelated.

HIV protease inhibitor substitution in patients with lipodystrophy: a randomized, controlled, open-label, multicentre study

BACKGROUND

Lipodystrophy, dyslipidaemia and insulin resistance often complicate protease inhibitor-containing antiretroviral therapy. The aims of this study were to determine if these are reversible with continued HIV suppression following protease inhibitor substitution.

METHODS

Eighty-one HIV protease inhibitor recipients (78 male; mean antiretroviral therapy, 55 months) with predominant peripheral lipoatrophy, HIV RNA < 400 copies/ml plasma for at least the preceding 6 months, and no prior abacavir, non-nucleoside analogue or adefovir therapy were randomized 3 : 2 to continue nucleoside analogues and substitute protease inhibitor(s) with abacavir, nevirapine, adefovir and hydroxyurea (n = 49) or to continue all therapy (n = 32) with an option to switch at week 24. The primary endpoints were total body fat and HIV RNA at week 24. Other assessments were regimen safety, regional body composition, metabolic parameters, quality of life, and CD4 T-lymphocyte counts to week 48.

RESULTS

There was a greater decline in total body fat in the switch group than in the continue group (-1.6 and -0.4 kg, respectively at week 24; P = 0.006). This comprised greater declines in limb and subcutaneous abdominal fat, and in intra-abdominal fat of patients with moderate or severe abdominal fat accumulation. Viral suppression was similar, despite 18 (37%) switch group patients ceasing at least one study drug by week 24 because of adverse events. Total cholesterol and triglycerides declined more in the switch group (both P < 0.002). High density lipoprotein cholesterol increased significantly in both groups at week 48 (P < 0.02). There was no change for any glycaemic parameter.

CONCLUSIONS

In predominantly lipoatrophic patients, switching from HIV protease inhibitor therapy lead to improved lipids and less intra-abdominal fat, but also to less peripheral fat, and had minimal effect on insulin resistance. Virological control in these heavily pretreated patients was unaffected, despite frequent switch drug cessations.

The disparity between hypothermic coagulopathy and clotting studies

Hypothermic patients commonly develop coagulopathy, but the effects of hypothermia on coagulation remain unclear because clinical laboratories routinely perform clotting tests only at 37 degrees C. Measurements of activated partial thromboplastin times (APTT), prothrombin times (PT), and thrombin times (TT) were performed on plasma from normothermic and hypothermic rats at a range of temperatures (25 degrees-37 degrees C) to assess the effects of hypothermia on apparent clotting factor levels and clotting factor activities. In general, clotting times were more severely prolonged when test temperatures were hypothermic than when body temperatures were hypothermic. Indeed, little to no prolongation resulted from body hypothermia alone. These findings reveal the observed disparity between clinically evident hypothermic coagulopathy and near-normal clotting studies. Clotting studies performed at 37 degrees C will not confirm hypothermic coagulopathy. These results indicate that the appropriate treatment for hypothermia-induced coagulopathy is rewarming rather than administration of clotting factors.

A first-generation whole genome-radiation hybrid map spanning the mouse genome

We have assembled a first-generation anchor map of the mouse genome using a panel of 94 whole-genome-radiation hybrids (WG-RHs) and 271 sequence-tagged sites (STSs). This is the first genome-wide RH anchor map of a model organism. All of the STSs have been previously localized on the genetic map and are located 8.8 Mb apart on average. This mouse WG-RH panel, known as T31, has an average retention frequency of 27.6% and an estimated potential resolution of 145 kb, making it a powerful resource for efficient large-scale expressed sequence tag mapping. [All of the mapping data for the maps presented here have been deposited at the Research Genetics, Inc., web site and can be freely accessed and downloaded at http://www.resgen.com/.]

Spermiogenesis is impaired in mice bearing a targeted mutation in the protein phosphatase 1cgamma gene

Type 1 protein phosphatases (PP1) are involved in diverse cellular activities, ranging from glycogen metabolism to chromatin structure modification, mitosis, and meiosis. The holoenzymes are composed of two or more subunits, including a catalytic subunit (PP1c) and one or more regulatory subunits. Many eukaryotes possess several catalytic subunit genes which encode highly conserved isoforms. In rodents, one of these isoforms, PP1cgamma2, appears to be expressed predominantly in testes. Whether PP1cgamma2 performs a testis-specific function is unclear. To address this and other questions, the PP1cgamma gene was disrupted by targeted insertion in murine embryonic stem cells. Mice derived from these cells were viable, and homozygous females were fertile. However, males homozygous for the targeted insertion were infertile. Histological examination revealed severe impairment of spermiogenesis beginning at the round spermatid stage. In addition, defects in meiosis were inferred from the presence of polyploid spermatids. Immunohistochemistry revealed the presence of PP1calpha protein on condensing spermatids in both wild-type and mutant testes, suggesting that this closely related isoform is unable to compensate for the loss of PP1cgamma. These defects are discussed in the light of known functions of protein phosphatase 1.

Identification of regions of the SV40 genome which contain preferred SV40 T antigen-binding sites

SV40 T antigen binds to SV40 DNA. Using a series of purified SV40 DNA restriction fragments, we have obtained evidence indicating that the antigen preferentially binds to three specific regions. These binding regions are contained within Endo R-Hin d(II + III) A, B, and C.

The wee1 protein kinase is required for radiation-induced mitotic delay

Cellular feedback or 'checkpoint' mechanisms maintain the order of completion of essential, cell-cycle related functions. In the budding yeast, for example, the RAD9 gene product is required to delay progression into mitosis in response to DNA damage. Similarly, in fission yeast, the cdc25 and cdc2 gene products influence the ability of cells to delay mitosis in response to the inhibition of DNA synthesis. Because these two checkpoint controls regulate the same event, mitosis, we observed the effect of gamma-irradiation on cell cycle progression in fission yeast, to test whether the two controls require the same cell-cycle regulatory elements. We show that gamma-radiation-induced mitotic delay requires functional wee1 protein kinase but does not seem to involve the cdc25 pathway. Mitotic delay in response to DNA damage is thus distinct from the delay induced by inhibition of DNA synthesis, which involves cdc25 but is not dependent on wee1.

The cdr2(+) gene encodes a regulator of G2/M progression and cytokinesis in Schizosaccharomyces pombe

Schizosaccharomyces pombe cells respond to nutrient deprivation by altering G2/M cell size control. The G2/M transition is controlled by activation of the cyclin-dependent kinase Cdc2p. Cdc2p activation is regulated both positively and negatively. cdr2(+) was identified in a screen for regulators of mitotic control during nutrient deprivation. We have cloned cdr2(+) and have found that it encodes a putative serine-threonine protein kinase that is related to Saccharomyces cerevisiae Gin4p and S. pombe Cdr1p/Nim1p. cdr2(+) is not essential for viability, but cells lacking cdr2(+) are elongated relative to wild-type cells, spending a longer period of time in G2. Because of this property, upon nitrogen deprivation cdr2(+) mutants do not arrest in G1, but rather undergo another round of S phase and arrest in G2 from which they are able to enter a state of quiescence. Genetic evidence suggests that cdr2(+) acts as a mitotic inducer, functioning through wee1(+), and is also important for the completion of cytokinesis at 36 degrees C. Defects in cytokinesis are also generated by the overproduction of Cdr2p, but these defects are independent of wee1(+), suggesting that cdr2(+) encodes a second activity involved in cytokinesis.

Effects of a medicine review and education programme for older people in general practice

AIMS

To determine whether a medicine review and education programme influences the compliance and knowledge of older people in general practice.

METHODS

Older people taking at least three medicines were randomly allocated to a control or intervention group. Both groups received three visits from a clinical pharmacist: Visit 1: Assessment and patients' medicines rationalized in intervention group. Visit 2: Intervention group given medicines education. Visit 3: Knowledge and compliance in both groups assessed by structured questionnaire

RESULTS

Compliance in the intervention group was 91.3%, compared with 79.5% in the control group (P < 0.0001). The number of intervention group patients correctly understanding the purpose of their medicines increased from 58% to 88% on the second visit, compared with 67% to 70% in the control group (P < 0.0005).

CONCLUSIONS

A general practice based medication review and education programme improved medicine compliance and knowledge of older people in the short term.

A randomised, open-label comparison of three highly active antiretroviral therapy regimens including two nucleoside analogues and indinavir for previously untreated HIV-1 infection: the OzCombo1 study

BACKGROUND

Highly active antiretroviral therapy (HAART) including two nucleoside analogues and a potent protease inhibitor is standard of care initial therapy for HIV-infected adults. The best-tolerated and most potent initial HAART regimen is unknown and was investigated in this study.

METHODS

One hundred and nine HIV-infected adults with no prior antiretroviral therapy, and CD4 lymphocyte counts < 500 x 10(6) cells/l or plasma HIV RNA > 30,000 copies/ml were randomized to zidovudine-lamivudine-indinavir (ZDV-3TC-IDV), stavudine-lamivudine-indinavir (d4T-3TC-IDV) or stavudine-didanosine-indinavir (d4T-ddI-IDV) for 52 weeks. The primary endpoints were plasma HIV RNA and drug-related adverse events. Other assessments were overall safety, adherence and adverse events, CD4 lymphocyte counts, cutaneous delayed type hypersensitivity (DTH) responses and quality of life (Euroqol).

RESULTS

Only 58% patients had HIV RNA < 50 copies/ml plasma at 12 months, with no significant difference between the three regimes (P = 0.34). Drug-related adverse events sufficiently severe to warrant drug discontinuation were less common (P = 0.06) in patients receiving d4T-3TC-IDV (18%) than in those receiving ZDV-3TC-IDV (34%) or d4T-ddI-IDV (41%). The percentages of patients who remained on their assigned therapy with plasma HIV RNA < 50 copies/ml at 52 weeks were 60% with d4T-3TC-IDV, 53% with ZDV-3TC-IDV and 35% with d4T-ddI-IDV. Virological failure at 52 weeks was more likely in those whose adherence was estimated to be < 100% in the first 4 weeks of therapy (P = 0.02), but not in those who developed grade 3 or 4 drug-related adverse events. At 52 weeks, the mean CD4 lymphocyte count increase was 200 x 10(6) cells/l with only 7% of patients having counts lower than at baseline; DTH responses improved but remained clinically impaired in most patients. Quality of life improved significantly in all groups.

CONCLUSIONS

Initial HAART regimens including IDV failed to suppress plasma HIV RNA to < 50 copies/ml in > 40% patients after only 12 months of therapy although there was significant overall improvement immunologically and in quality of life. The type of dual nucleoside combination used was less important in predicting virological failure than was imperfect adherence early in therapy. Consideration should be given to modifying a HAART regimen relatively early in non-adherent patients.

Low HDL cholesterol, aggression and altered central serotonergic activity

Many studies support a significant relation between low cholesterol levels and poor impulse, aggression and mood control. Evidence exists also for a causal link between low brain serotonin (5-HT) activity and these behaviors. Mechanisms linking cholesterol and hostile or self-destructive behavior are unknown, but it has been suggested that low cholesterol influences 5-HT function. This study was designed to explore the relationship between plasma cholesterol, measures of impulsivity and aggression, and indices of 5-HT function in personality disordered cocaine addicts. Thirty-eight hospitalized male patients (age 36.8+/-7.1) were assessed with the DSM-III-R, the Buss-Durkee Hostility Inventory (BDHI), the Barratt Impulsiveness Scale (BIS) and the Brown-Goodwin Assessment for Life History of Aggression. Fasting basal cholesterol (total, LDL and HDL) was determined 2 weeks after cocaine discontinuation. On the same day 5-HT function was assessed by neuroendocrine (cortisol and prolactin) and psychological (NIMH and 'high' self-rating scales) responses following meta-chlorophenylpiperazine (m-CPP) challenges. Reduced neuroendocrine responses, 'high' feelings and increased 'activation-euphoria' following m-CPP have been interpreted as indicating 5-HT alterations in a variety of psychiatric conditions. Significantly lower levels of HDL cholesterol were found in patients who had a history of aggression (P=0.005). Lower levels of HDL cholesterol were also found to be significantly associated with more intense 'high' and 'activation-euphoria' responses as well as with blunted cortisol responses to m-CPP (P=0.033, P=0.025 and P=0.018, respectively). This study gives further support to existing evidence indicating that in some individuals, the probability of exhibiting impulsive and violent behaviors may be increased when cholesterol is low. It also suggests that low cholesterol and alterations in 5-HT activity may be causally related.

Femoral morphology and cross-sectional geometry of adult myostatin-deficient mice

GDF-8, also known as myostatin, is a member of the transforming growth factor-beta (TGF-beta) superfamily of secreted growth and differentiation factors that is expressed in vertebrate skeletal muscle. Myostatin functions as a negative regulator of skeletal muscle growth and myostatin null mice show a doubling of muscle mass compared with normal mice. We examined femoral morphology of adult myostatin-deficient mice to assess the effects of muscle fiber hypertrophy and hyperplasia on bone shape and cross-sectional geometry. Femora of age- and weight-matched adult mice homozygous for the disrupted myostatin sequence were compared with those of wild-type controls (n = 8 per group). Results show that, as was the case in previous studies, myostatin null mice have hindlimb muscle masses that are approximately double those of controls. Myostatin-deficient mice exhibit third trochanters that are significantly larger than those of controls, whereas the femoral midshafts of the control and experimental mice do not differ significantly from one another in cortical area, bending moment of inertia, and polar moment of inertia. Our findings indicate that the increased muscle mass of myostatin-deficient mice primarily affects sites of muscle insertion, but does not induce additional cortical bone deposition in the diaphysis relative to controls. We therefore conclude that the expanded third trochanters of myostatin-deficient subjects result from tendon and Sharpey fiber expansion associated with muscle growth rather than cortical bone deposition in response to increased levels of mechanical stress.

Ectodysplasin-A1 is sufficient to rescue both hair growth and sweat glands in Tabby mice

Mutations in the human ectodysplasin-A (EDA) are responsible for the most common form of the ectodermal dysplasia and the defective orthologous gene in mice produces the tabby phenotype, suggesting its vital role in the development of hair, sweat glands and teeth. Among several EDA splice isoforms, the most common and the longest EDA splice isoforms, EDA-A1 and EDA-A2, differing by only two amino acids, activate NF-kappaB-promoted transcription by binding to distinct receptors, EDAR and XEDAR. The extent to which any particular isoform is sufficient for the formation of hair, sweat glands or teeth has remained unclear. Here we report that transgenic expression of the mouse EDA-A1 isoform in tabby (EDA-less) males rescued development of several skin appendages. The transgenic tabby mice showed almost complete restoration of hair growth, dermal ridges, sweat glands and molars. The number of hair follicles in the transgenic mice is the same as in wild-type; though the development of follicles and associated glands varies from indistinguishable from wild-type to smaller and/or only partially formed. These results suggest that the other EDA isoforms may not be absolutely required for skin appendage formation, but consistent with distinctive temporal and spatial expression of the EDA-A2 isoform, are likely required for appropriate timing and completeness of development. Our data provide the first direct physiological evidence that EDA-A1 is a key regulator of hair follicle and sweat gland initiation; its soluble ligand form could aid in deriving therapeutic reagents for conditions affecting hair and sweat gland formation.

Enamel wear caused by three different restorative materials

The ideal restorative material should cause minimal wear of opposing enamel. This study compared the effects of gold alloy, glazed porcelain, and a laboratory-processed composite on opposing enamel. Ten samples of a type III gold alloy, a porcelain, and a visible-light, heat, and vacuum-processed composite were abraded against cusps of extracted molars for 10,000 cycles on an abrading machine. Pretest and posttest profilometric measurements of the restorative materials demonstrated no statistical difference. Pretest and posttest tracings of the cusps were made on an optical comparator to determine loss of vertical height and surface area. The porcelain caused significantly more loss of vertical height and surface area than the gold alloy or the composite, which were similar.

Extent of linkage disequilibrium between the androgen receptor gene CAG and GGC repeats in human populations: implications for prostate cancer risk

While studies have implicated alleles at the CAG and GGC trinucleotide repeats of the androgen receptor gene with high-grade, aggressive prostate cancer disease, little is known about the normal range of variation for these two loci, which are separated by about 1.1 kb. More importantly, few data exist on the extent of linkage disequilibrium (LD) between the two loci in different human populations. Here we present data on CAG and GGC allelic variation and LD in six diverse populations. Alleles at the CAG and GGC repeat loci of the androgen receptor were typed in over 1000 chromosomes from Africa, Asia, and North America. Levels of linkage disequilibrium between the two loci were compared between populations. Haplotype variation and diversity were estimated for each population. Our results reveal that populations of African descent possess significantly shorter alleles for the two loci than non-African populations (P<0.0001). Allelic diversity for both markers was higher among African Americans than any other population, including indigenous Africans from Sierra Leone and Nigeria. Analysis of molecular variance revealed that approx. 20% of CAG and GGC repeat variance could be attributed to differences between the populations. All non-African populations possessed the same common haplotype while the three populations of African descent possessed three divergent common haplotypes. Significant LD was observed in our sample of healthy African Americans. The LD observed in the African American population may be due to several reasons; recent migration of African Americans from diverse rural communities following urbanization, recurrent gene flow from diverse West African populations, and admixture with European Americans. This study represents the largest genotyping effort to be performed on the two androgen receptor trinucleotide repeat loci in diverse human populations.

Suppression of microtubule dynamic instability and treadmilling by deuterium oxide

Deuterium oxide (D(2)O) is known to promote the assembly of tubulin into microtubules in vitro, to increase the volume of mitotic spindles and the number and length of spindle microtubules, and to inhibit mitosis. Reasoning that its actions on cellular microtubules could be due to modulation of microtubule dynamics, we examined the effects of replacing H(2)O with D(2)O on microtubule dynamic instability, treadmilling, and steady-state GTPase activity. We found that replacing 50% or more of the H(2)O with D(2)O promoted microtubule polymerization and stabilized microtubules against dilution-induced disassembly. Using steady-state axoneme-seeded microtubules composed of pure tubulin and video microscopy, we found that 84% D(2)O decreased the catastrophe frequency by 89%, the shortening rate by 80%, the growing rate by 50%, and the dynamicity by 93%. Sixty percent D(2)O decreased the treadmilling rate of microtubules composed of tubulin and microtubule-associated proteins by 42%, and 89% D(2)O decreased the steady-state GTP hydrolysis rate by 90%. The mechanism responsible for the ability of D(2)O to stabilize microtubule dynamics may involve enhancement of hydrophobic interactions in the microtubule lattice and/or the substitution of deuterium bonds for hydrogen bonds.

Estrogen and muscle stiffness have a negative relationship in females

PURPOSE

Hormonal fluctuations are one potential reason why females might have a greater rate of noncontact ACL injury. The hamstrings are capable of limiting anterior cruciate ligament (ACL) loading. This study examined whether relationships existed between reproductive hormones (estradiol-β-17, free testosterone, and progesterone) and hamstring neuromechanical variables (hamstring musculotendinous stiffness (MTS), rate of force production (RFP), time to 50% peak torque (T50%), and electromechanical delay (EMD)) in genders combined and independently.

METHODS

Muscle properties of the hamstrings and reproductive hormones were evaluated in 30 subjects (15 males and 15 females) that were free from lower extremity injury and had no history of ACL injury. Females were tested 3-5 days after the onset of menses and were not using oral contraceptive. Pearson correlation coefficients were calculated for each hormone and muscle property.

RESULTS

For genders combined, estrogen (mean = 46.0 ± 28.2 pg/mL) was negatively correlated with RFP (mean = 758.8 ± 507.6 N/kg s(-1), r = -0.43, P = 0.02) and MTS (mean = 12.8 ± 2.6 N/cm, r = -0.43, P = 0.02). Free testosterone (mean = 13.2 ± 13.0 pg/mL) was positively correlated with RFP (r = 0.56, P < 0.01) and MTS (r = 0.46, P = 0.01) but negatively correlated with T50% (mean = 114.7 ± 38.9 ms, r = -0.43, P = 0.02). When gender was considered separately, females demonstrated negative correlation between estrogen (mean = 68.0 ± 23.2 pg/mL) and MTS (mean = 11.7 ± 1.5 N/cm, r = -0.53, P = 0.05) and free testosterone (mean = 1.5 ± 0.6 pg/mL) and MTS (r = -0.52, P = 0.05). Males alone displayed no significant correlations between the selected hormones and muscle properties.

CONCLUSIONS

Correlations exist between muscle properties and reproductive hormones. Females, however, may be more sensitive to reproductive hormones and their fluctuations.