Marrow stromal stem cells

Evidence for the hypothesis that there are stromal stem cells present in the soft connective tissues associated with marrow and bone surfaces that are able to give rise to a number of different cell lines is reviewed. The lines are currently designated fibroblastic, reticular, adipocytic and osteogenic. Fibroblastic colonies, each derived from a single colony-forming unit fibroblastic (CFU-F), are formed when marrow cells are cultured in vitro. In vivo assays of tissue formed by CFU-F in open transplant or in diffusion chambers, have demonstrated that some CFU-F have a high ability for self renewal and multipotentiality whereas some have more limited potential. Preliminary investigations in vitro also support the hypothesis and have shown that CFU-F are a heterogeneous population of stem and progenitor cells and that their differentiation in vitro can be modified at the colony level. The stromal cells which survive and proliferate in vitro are highly dependent on culture conditions. The number and hierarchy of cell lines belonging to the stromal fibroblastic system are not yet fully elucidated and more specific markers and better assays for the different phenotypes are required before a greater understanding can be achieved. The possibility that the marrow stromal system is part of a wider stromal cell system of the body is proposed.

Mutations in ATP2A2, encoding a Ca2+ pump, cause Darier disease

Darier disease (DD) is an autosomal-dominant skin disorder characterized by loss of adhesion between epidermal cells (acantholysis) and abnormal keratinization. Recently we constructed a 2.4-Mb, P1-derived artificial chromosome contig spanning the DD candidate region on chromosome 12q23-24.1. After screening several genes that mapped to this region, we identified mutations in the ATP2A2 gene, which encodes the sarco/endoplasmic reticulum Ca2(+)-ATPase type 2 isoform (SERCA2) and is highly expressed in keratinocytes. Thirteen mutations were identified, including frameshift deletions, in-frame deletions or insertions, splice-site mutations and non-conservative missense mutations in functional domains. Our results demonstrate that mutations in ATP2A2 cause DD and disclose a role for this pump in a Ca(2+)-signalling pathway regulating cell-to-cell adhesion and differentiation of the epidermis.

Family-based association study of 76 candidate genes in bipolar disorder: BDNF is a potential risk locus. Brain-derived neutrophic factor

Identification of the genetic bases for bipolar disorder remains a challenge for the understanding of this disease. Association between 76 candidate genes and bipolar disorder was tested by genotyping 90 single-nucleotide polymorphisms (SNPs) in these genes in 136 parent-proband trios. In this preliminary analysis, SNPs in two genes, brain-derived neurotrophic factor (BDNF) and the alpha subunit of the voltage-dependent calcium channel were associated with bipolar disorder at the P<0.05 level. In view of the large number of hypotheses tested, the two nominally positive associations were then tested in independent populations of bipolar patients and only BDNF remains a potential risk gene. In the replication samples, excess transmission of the valine allele of amino acid 66 of BDNF was observed in the direction of the original result in an additional sample of 334 parent-proband trios (T/U=108/87, P=0.066). Resequencing of 29 kb surrounding the BDNF gene identified 44 additional SNPs. Genotyping eight common SNPs identified three additional markers transmitted to bipolar probands at the P < 0.05 level. Strong LD was observed across this region and all adjacent pairwise haplotypes showed excess transmission to the bipolar proband. Analysis of these haplotypes using TRANSMIT revealed a global P value of 0.03. A single haplotype was identified that is shared by both the original dataset and the replication sample that is uniquely marked by both the rare A allele of the original SNP and a novel allele 11.5 kb 3'. Therefore, this study of 76 candidate genes has identified BDNF as a potential risk allele that will require additional study to confirm.

Stromal stem cells: marrow-derived osteogenic precursors

Evidence is discussed for the hypothesis that there are stromal stem cells present in the soft connective tissues associated with marrow and bone surfaces that are able to give rise to a number of different cell lines including the osteogenic line. Fibroblastic colonies, each derived from a single colony-forming unit fibroblastic (CFU-F), are formed when marrow cells are cultured in vitro. In vivo assays of CFU-F have demonstrated that some CFU-F have a high ability for self renewal and multipotentiality whereas some have more limited potential. In vitro studies also support the hypothesis and have shown that CFU-F are a heterogeneous population of stem and progenitor cells and that their differentiation in vitro can be modified at the colony level. Factors added to the medium can activate osteogenesis in a range of multipotential and more committed precursors. Different stromal cell lines can be promoted under different culture conditions. The number and hierarchy of cell lines belonging to the stromal fibroblastic system are not yet fully elucidated and more specific markers for the different lines are required before a better understanding can be achieved.

Cbfa1 is required for epithelial-mesenchymal interactions regulating tooth development in mice

Osteoblasts and odontoblasts, cells that are responsible for the formation of bone and dentin matrices respectively, share several molecular characteristics. Recently, Cbfa1 was shown to be a critical transcriptional regulator of osteoblast differentiation. Mutations in this gene cause cleidocranial dysplasia (CCD), an autosomal dominant disorder in humans and mice characterized by defective bone formation. CCD also results in dental defects that include supernumerary teeth and delayed eruption of permanent dentition. The dental abnormalities in CCD suggest an important role for this molecule in the formation of dentition. Here we describe results of studies aimed at understanding the functions of Cbfa1 in tooth formation. RT-PCR and in situ hybridization analyses show that Cbfa1 has a unique expression pattern in dental mesenchyme from the bud to early bell stages during active epithelial morphogenesis. Unlike that observed in osteoblast differentiation, Cbfa1 is downregulated in fully differentiated odontoblasts and is surprisingly expressed in ectodermally derived ameloblasts during the maturation phase of enamel formation. The role of Cbfa1 in tooth morphogenesis is further illustrated by the misshapen and severely hypoplastic tooth organs in Cbfa1−/− mice. These tooth organs lacked overt odontoblast and ameloblast differentiation and normal dentin and enamel matrices. Epithelial-mesenchymal recombinants demonstrate that dental epithelium regulates mesenchymal Cbfa1 expression during the bud and cap stages and that these effects are mimicked by the FGFs but not by the BMPs as shown by our bead implantation assays. We propose that Cbfa1 regulates the expression of molecules in mesenchyme that act reciprocally on dental epithelium to control its growth and differentiation. Taken together, our data indicate a non-redundant role for Cbfa1 in tooth development that may be distinct from that in bone formation. In odontogenesis, Cbfa1 is not involved in the early signaling networks regulating tooth initiation and early morphogenesis but regulates key epithelial-mesenchymal interactions that control advancing morphogenesis and histodifferentiation of the epithelial enamel organ.

A combined analysis of D22S278 marker alleles in affected sib-pairs: support for a susceptibility locus for schizophrenia at chromosome 22q12. Schizophrenia Collaborative Linkage Group (Chromosome 22)

Several groups have reported weak evidence for linkage between schizophrenia and genetic markers located on chromosome 22q using the lod score method of analysis. However these findings involved different genetic markers and methods of analysis, and so were not directly comparable. To resolve this issue we have performed a combined analysis of genotypic data from the marker D22S278 in multiply affected schizophrenic families derived from 11 independent research groups worldwide. This marker was chosen because it showed maximum evidence for linkage in three independent datasets (Vallada et al., Am J Med Genet 60:139-146, 1995; Polymeropoulos et al., Neuropsychiatr Genet 54:93-99, 1994; Lasseter et al., Am J Med Genet, 60:172-173, 1995. Using the affected sib-pair method as implemented by the program ESPA, the combined dataset showed 252 alleles shared compared with 188 alleles not share (chi-square 9.31, 1df, P = 0.001) where parental genotype data was completely known. When sib-pairs for whom parental data was assigned according to probability were included the number of alleles shared was 514.1 compared with 437.8 not shared (chi-square 6.12, 1df, P = 0.006). Similar results were obtained when a likelihood ratio method for sib-pair analysis was used. These results indicate that may be a susceptibility locus for schizophrenia at 22q12.

Pre-morbid adjustment and personality in psychosis. Effects of sex and diagnosis

Pre-morbid schizoid and schizotypal traits and social adjustment were assessed blind to diagnosis by interviewing the mothers of 73 consecutively admitted patients with DSM-III schizophrenia or affective psychosis. Analysis of factors associated with pre-morbid deficits showed a highly significant interaction of diagnosis with sex, such that schizophrenic men showed much greater pre-morbid impairment than either schizophrenic women or men with affective disorder. Poor pre-morbid adjustment predicted an early age at first admission. The results can be explained by a neurodevelopmental disorder in some schizophrenic males.

Polyclonal antibody directed against human RANTES ameliorates disease in the Lewis rat adjuvant-induced arthritis model

Adjuvant-induced arthritis (AIA) is one of many animal models of rheumatoid arthritis, a disease characterized by a T-lymphocyte and macrophage cellular infiltrate. We have characterized the development of this disease model with respect to chemokine expression. Increased levels of two chemokines, RANTES, a T-lymphocyte and monocyte chemo-attractant, and KC a chemoattractant for neutrophils, were found in whole blood and in the joint. Surprisingly, levels of MIP-1alpha, another T-lymphocyte and monocyte chemoattractant, were unchanged throughout the course of the disease in whole blood and only slightly elevated in the joint. RANTES expression plays an important role in the disease since a polyclonal antibody to RANTES greatly ameliorated symptoms in animals induced for AIA and was found to be as efficacious as treatment with indomethacin, a non-steroidal anti inflammatory. Polyclonal antibodies to either MIP-1alpha or KC were ineffective. This is the first report to show the importance of RANTES in the development of AIA.

Synthesis of a functional anti-phytochrome single-chain Fv protein in transgenic tobacco

We have expressed a synthetic gene that encodes an antigen-binding single-chain FV protein (scFV) in transgenic tobacco plants. The scFV gene was created by polymerase chain reaction (PCR) amplification of the variable domain coding regions from a mouse monoclonal hybridoma cell line. The monoclonal cell line secretes an IgG1 antibody that binds to the plant regulatory photoreceptor protein, phytochrome. The cloned scFV gene was expressed initially in Escherichia coli and shown to produce a 28 kD, phytochrome-binding binding scFV protein. Transgenic tobacco plants expressing the scFV gene were also found to produce a functional scFV protein, and seeds from transgenic R1 progeny displayed aberrant phytochrome-dependent germination. The scFV from transgenic tobacco could be isolated, to near homogeneity, by a single phytochrome-Sepharose affinity chromatography step.

Serotonergic system and attention deficit hyperactivity disorder (ADHD): a potential susceptibility locus at the 5-HT(1B) receptor gene in 273 nuclear families from a multi-centre sample

Attention deficit hyperactivity disorder (ADHD) is a highly heritable and heterogeneous disorder, which usually becomes apparent during the first few years of childhood. Imbalance in dopamine neurotransmission has been suggested as a factor predisposing to ADHD. However, evidence has suggested an interaction between dopamine and serotonin systems in the pathophysiology of the disorder. Studies using selective agonists of the different 5-HT receptors microinjected into selected brain structures have shown a positive modulating effect on the functional activities of the mesotelencephalic dopaminergic system. This suggests that some of the genetic predisposition to ADHD might be due to DNA variation at serotonin system genes. In this study, we investigated polymorphisms in HTR(1B) and HTR(2A) (which encode the serotonin receptors 5-HT(1B) and 5-HT(2A) respectively) in a European ADHD sample. Using haplotype based haplotype relative risk (HHRR) and transmission disequilibrium test (TDT) analyses, we observed significant preferential transmission of the allele 861G of the HTR(1B) in the total sample (for HHRR; chi(2) = 7.4, P = 0.0065 and TDT; (chi(2) = 6.4, P = 0.014). Analysis of HTR(2A) failed to reveal evidence of association or linkage between the His452Tyr polymorphism and ADHD in the total sample. However, a significantly increased transmission of the allele 452His was observed in the Irish sample alone (chi(2) = 4.9, P = 0.026). These preliminary data suggest an important role for the serotonin system in the development of ADHD. Further studies, preferentially including different ethnic groups are required to substantiate these findings.

Studies on the concentration and intracellular localization of iron proteins in liver biopsy specimens from patients with iron overload with special reference to their role in lysosomal disruption

Liver biopsies were collected from control subjects and patients with iron overload due to either primary or secondary haemochromatosis. They were analysed for iron proteins by cation exchange chromatography and flameless atomic absorption spectrophotometry. In control tissue the transferrin fraction contains 25%, ferritin 50% and haemprotein and haemosiderin 10--15% each, of the total iron. In iron overloaded tissue the ferritin and haemosiderin iron increases approximately 10- and 100-fold, respectively, compared with control tissue. There was a close positive correlation between enhanced lysosomal fragility as determined by measurements of latent N-acetyl-beta-glucosaminidase and haemosiderin content of the tissue; it is suggested that the haemosiderin is responsible for the lysosomal disruption and hence the tissue damage in iron overload. Studies were performed on the intracellular localization of ferritin and of total iron in biopsy extracts from control subjects and from patients with iron overload. In control tissue, ferritin contains most of the iron and is apparently free in the cytosol. In iron overload, ferritin is the major iron protein in the post-nuclear supernatant sedimenting into the gradient as the free protein. There are, however, significant amounts of immunoreactive ferritin deeper in the gradients but this cannot be assigned to any particular subcellular organelle. The extreme fragility of lysosomes in iron overloaded human tissue makes isolation of these organelles for detailed biochemical analysis extremely difficult.

Motor cortical representation of the diaphragm in man

1. Transcranial magnetic stimulation was performed using a figure-of-eight-shaped coil over the right motor cortex with the aim of identifying those areas involved with activation of the diaphragm. 2. The response of the right and left hemi-diaphragms was recorded using surface electrodes in either the 7th or 8th intercostal spaces 3 cm lateral to the anterior costal margin on either side. 3. The compound muscle action potentials recorded over the left diaphragm in response to transcranial magnetic stimulation were maximal when the centre of the figure-of-eight coil was placed approximately 3 cm to the right of the mid-line and 2-3 cm anterior to the auricular plane. 4. The amplitude of the response recorded from the diaphragm depended upon the angulation of the figure-of-eight coil and hence the direction of the stimulating current. 5. The response of the inspiratory muscles to magnetic stimulation of one side of the brain was predominantly contralateral but a small response was seen on the ipsilateral side. Ultrasonic techniques confirmed that the diaphragm was responding contralaterally and not ipsilaterally.

A family-based and case-control association study of the dopamine D4 receptor gene and dopamine transporter gene in attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a highly heritable psychiatric condition of early childhood onset characterised by marked inattention, hyperactivity and impulsiveness. Molecular genetic investigations of ADHD have found positive associations with the 480-bp allele of a VNTR situated in the 3' untranslated region of DAT1 and allele 7 of a VNTR in exon 3 of DRD4. A number of independent studies have attempted to replicate these findings but the results have been inconsistent. We used both family-based and case control approaches to examine these polymorphisms in a sample of 137 children diagnosed with ICD-10, DSM-IV or DSM-III-R ADHD. We found no evidence of association with the DAT1 polymorphism, despite a sample size that has up to 80% power to detect a previously reported effect size. We observed a significant increase in the DRD4 7 repeat allele amongst ADHD probands (21.7%) and their parents (18.9% in mothers, 22.3% in fathers), compared to ethnically matched controls (12.8%). However TDT analysis showed no preferential transmission of allele 7 to ADHD probands.

The strength of the genetic effect. Is there room for an environmental influence in the aetiology of schizophrenia?

The evidence for a genetic contribution to schizophrenia is compelling. However, the pattern of inheritance is complex and it is usually assumed that environmental factors also have a role that will eventually be identified. We argue that this is not necessarily the case. While a hypothesis combining genetic diathesis with environmental stress cannot be disproved, it is also possible that 'non-genetic' factors consist entirely of stochastic events affecting gene expression or structure.

Familial cosegregation of major affective disorder and Darier's disease (keratosis follicularis)

Darier's disease is a rare autosomal dominantly inherited keratosis. This is an account of one family in which there is co-occurrence of major affective disorder and Darier's disease in five members and absence of both disorders in five members. The pedigree is consistent with genetic linkage between the Darier gene and a major autosomal dominant susceptibility locus for major affective disorder. When the Darier's disease gene has been mapped, its chromosomal location will be an interesting candidate locus for linkage studies of major affective disorder.

The effect of parathyroid extract on cellular activity and plasma calcium levels in vivo

Parathyroid hormone has a direct effect on the osteoclast population present at the time of administration of the hormone. There was a significant stimulation of nuclear RNA synthesis at the earliest time (1½ hr.) at which the measurement could be made. This is followed by increased production of cytoplasmic RNA which reaches its maximum after a considerable time-lag (7 to 12 hr. after parathyroid extract (PTE)). The increase in cytoplasmic RNA is accompanied by a corresponding stimulation of protein and mucoprotein synthesis in the osteoclasts and the effect persists at least until 24 hr. This time-lag and the relatively long duration of the effect on protein synthesis can be correlated approximately with the effect on the plasma calcium level. It is suggested therefore that the rise in plasma calcium is mainly due to the increased cellular activity of the osteoclasts and the resulting increased bone resorption. The opposite effect on the osteoblast system has about the same time-sequence and would complement the effect on the osteoclast system. At about the same time as the maximum increase in cellular activity in the osteoclasts is observed, a significant effect on RNA synthesis in the endosteal mesenchymal cells, the precursors of the osteoclasts, becomes apparent. This is closely followed by a rise in the number of osteoclasts which is first apparent at 17 hr. after PTE and is maximal by 24 hr. Consequently, the rise in the number of osteoclasts is a secondary effect and is not responsible for the initial rise in plasma calcium which occurred much earlier. It is suggested that the increase in osteoclast numbers follows as a result of the increased metabolic activity of the osteoclast population present when the hormone was injected.

There is a depression of RNA synthesis in both the osteoblasts and their precursors, the preosteoblasts. This means that the hormone has opposite effects, not only on the osteoblasts and osteoclasts, but also on their respective precursors, indicating that osteoprogenitor cells contain a mixture of cells with two main lines, those differentiating in an osteoblastic or osteoclastic direction, respectively.

Suggestive evidence for linkage of schizophrenia to markers on chromosome 13q14.1-q32

Family, twin and adoption studies highlight the influence of genes in the aetiology of schizophrenia, though the mode of inheritance is unclear. We have been conducting a systematic search for major genes in schizophrenia using a series of multiply affected families and report preliminary results of linkage under heterogeneity with markers on chromosome 13. A lod2 score of 1.61 for marker D13S144 was obtained at theta = 0 and alpha of 0.5 and nearby markers also produced positive values.

Herbicide-resistant crops and weed resistance to herbicides

The adoption of genetically modified (GM) crops has increased dramatically during the last 3 years, and currently over 52 million hectares of GM crops are planted world-wide. Approximately 41 million hectares of GM crops planted are herbicide-resistant crops, which includes an estimated 33.3 million hectares of herbicide-resistant soybean. Herbicide-resistant maize, canola, cotton and soybean accounted for 77% of the GM crop hectares in 2001. However, sugarbeet, wheat, and as many as 14 other crops have transgenic herbicide-resistant cultivars that may be commercially available in the near future. There are many risks associated with the production of GM and herbicide-resistant crops, including problems with grain contamination, segregation and introgression of herbicide-resistant traits, marketplace acceptance and an increased reliance on herbicides for weed control. The latter issue is represented in the occurrence of weed population shifts, the evolution of herbicide-resistant weed populations and herbicide-resistant crops becoming volunteer weeds. Another issue is the ecological impact that simple weed management programs based on herbicide-resistant crops have on weed communities. Asiatic dayflower (Commelina cumminus L) common lambsquarters (Chenopodium album L) and wild buckwheat (Polygonum convolvulus L) are reported to be increasing in prominence in some agroecosystems due to the simple and significant selection pressure brought to bear by herbicide-resistant crops and the concomitant use of the herbicide. Finally, evolution of herbicide-resistant weed populations attributable to the herbicide-resistant crop/herbicide program has been observed. Examples of herbicide-resistant weeds include populations of horseweed (Conyza canadensis (L) Cronq) resistant to N-(phosphonomethyl)glycine (glyphosate). An important question is whether or not these problems represent significant economic issues for future agriculture.

Examining for association between candidate gene polymorphisms in the dopamine pathway and attention-deficit hyperactivity disorder: a family-based study

Attention-deficit hyperactivity disorder (ADHD) is a highly heritable childhood-onset psychiatric condition characterized by developmentally inappropriate inattention, hyperactivity, and impulsiveness. The pathophysiology of ADHD is currently unknown. However, the therapeutic effects of stimulant medication together with findings from animal and neuroimaging studies as well as from several molecular genetic studies of the dopamine receptor D4 gene and dopamine transporter gene have implicated involvement of the dopaminergic system. To test the dopaminergic hypothesis further, we have looked for association between ADHD and alleles of seven dopamine-related candidate genes using a family-based association approach in a sample of 150 children diagnosed with ADHD. We tested polymorphisms in genes encoding three dopamine receptors (DRD3, DRD4, and DRD5) and four dopamine-relevant enzymes: tyrosine hydroxylase [tyrosine hydroxylase (TH)], dopamine beta hydroxylase (DbetaH), catechol-O-methyltransferase (COMT), and monoamine oxidase A (MAOA). We were unable to detect a significant association with any of the polymorphisms genotyped, although there was a trend for preferential transmission of the DRD5 148 bp marker allele and the MAOA 122 bp marker allele. We conclude that none of the alleles we have tested makes a major contribution to ADHD, although much larger samples are required to exclude small effects.

A comparison of epidural analgesia with 0.125% ropivacaine with fentanyl versus 0.125% bupivacaine with fentanyl during labor

We previously found that the extent of an epidural motor block produced by 0.125% ropivacaine was clinically indistinguishable from 0.125% bupivacaine in laboring patients. By adding fentanyl to the 0. 125% ropivacaine and bupivacaine solutions in an attempt to reduce hourly local anesthetic requirements, we hypothesized that differences in motor block produced by the two drugs may become apparent. Fifty laboring women were randomized to receive either 0. 125% ropivacaine with fentanyl 2 microg/mL or an equivalent concentration of bupivacaine/fentanyl using patient-controlled epidural analgesia (PCEA) with settings of: 6-mL/hr basal rate, 5-mL bolus, 10-min lockout, 30-mL/h dose limit. Analgesia, local anesthetic use, motor block, patient satisfaction, and side effects were assessed until the time of delivery. No differences in verbal pain scores, local anesthetic use, patient satisfaction, or side effects between groups were observed; however, patients administered ropivacaine/fentanyl developed significantly less motor block than patients administered bupivacaine/fentanyl. Ropivacaine 0.125% with fentanyl 2 microg/mL produces similar labor analgesia with significantly less motor block than an equivalent concentration of bupivacaine/fentanyl. Whether this statistical reduction in motor block improves clinical outcome or is applicable to anesthesia practices which do not use the PCEA technique remains to be determined.

IMPLICATIONS

By using a patient-controlled epidural analgesia technique, ropivacaine 0.125% with fentanyl 2 microg/mL produces similar analgesia with significantly less motor block than a similar concentration of bupivacaine with fentanyl during labor. Whether this statistical reduction in motor block improves clinical outcome or is applicable to anesthesia practices which do not use the patient-controlled epidural analgesia technique remains to be determined.

Herbicide-resistant crops: utilities and limitations for herbicide-resistant weed management

Since 1996, genetically modified herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, have transformed the tactics that corn, soybean, and cotton growers use to manage weeds. The use of GR crops continues to grow, but weeds are adapting to the common practice of using only glyphosate to control weeds. Growers using only a single mode of action to manage weeds need to change to a more diverse array of herbicidal, mechanical, and cultural practices to maintain the effectiveness of glyphosate. Unfortunately, the introduction of GR crops and the high initial efficacy of glyphosate often lead to a decline in the use of other herbicide options and less investment by industry to discover new herbicide active ingredients. With some exceptions, most growers can still manage their weed problems with currently available selective and HR crop-enabled herbicides. However, current crop management systems are in jeopardy given the pace at which weed populations are evolving glyphosate resistance. New HR crop technologies will expand the utility of currently available herbicides and enable new interim solutions for growers to manage HR weeds, but will not replace the long-term need to diversify weed management tactics and discover herbicides with new modes of action. This paper reviews the strengths and weaknesses of anticipated weed management options and the best management practices that growers need to implement in HR crops to maximize the long-term benefits of current technologies and reduce weed shifts to difficult-to-control and HR weeds.