The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

The genome of black cottonwood, Populus trichocarpa (Torr. & Gray)

We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.

Race, gender, and partnership in the patient-physician relationship

CONTEXT

Many studies have documented race and gender differences in health care received by patients. However, few studies have related differences in the quality of interpersonal care to patient and physician race and gender.

OBJECTIVE

To describe how the race/ethnicity and gender of patients and physicians are associated with physicians' participatory decision-making (PDM) styles.

DESIGN, SETTING, AND PARTICIPANTS

Telephone survey conducted between November 1996 and June 1998 of 1816 adults aged 18 to 65 years (mean age, 41 years) who had recently attended 1 of 32 primary care practices associated with a large mixed-model managed care organization in an urban setting. Sixty-six percent of patients surveyed were female, 43% were white, and 45% were African American. The physician sample (n = 64) was 63% male, with 56% white, and 25% African American.

MAIN OUTCOME MEASURE

Patients' ratings of their physicians' PDM style on a 100-point scale.

RESULTS

African American patients rated their visits as significantly less participatory than whites in models adjusting for patient age, gender, education, marital status, health status, and length of the patient-physician relationship (mean [SE] PDM score, 58.0 [1.2] vs 60.6 [3.3]; P = .03). Ratings of minority and white physicians did not differ with respect to PDM style (adjusted mean [SE] PDM score for African Americans, 59.2 [1.7] vs whites, 61.7 [3.1]; P = .13). Patients in race-concordant relationships with their physicians rated their visits as significantly more participatory than patients in race-discordant relationships (difference [SE], 2.6 [1.1]; P = .02). Patients of female physicians had more participatory visits (adjusted mean [SE] PDM score for female, 62.4 [1.3] vs male, 59.5 [3.1]; P = .03), but gender concordance between physicians and patients was not significantly related to PDM score (unadjusted mean [SE] PDM score, 76.0 [1.0] for concordant vs 74.5 [0.9] for discordant; P = .12). Patient satisfaction was highly associated with PDM score within all race/ethnicity groups.

CONCLUSIONS

Our data suggest that African American patients rate their visits with physicians as less participatory than whites. However, patients seeing physicians of their own race rate their physicians' decision-making styles as more participatory. Improving cross-cultural communication between primary care physicians and patients and providing patients with access to a diverse group of physicians may lead to more patient involvement in care, higher levels of patient satisfaction, and better health outcomes.

A family of human cdc2-related protein kinases

The p34cdc2 protein kinase is known to regulate important transitions in the eukaryotic cell cycle. We have identified 10 human protein kinases based on their structural relation to p34cdc2. Seven of these kinases are novel and the products of five share greater than 50% amino acid sequence identity with p34cdc2. The seven novel genes are broadly expressed in human cell lines and tissues with each displaying some cell type or tissue specificity. The cdk3 gene, like cdc2 and cdk2, can complement cdc28 mutants of Saccharomyces cerevisiae, suggesting that all three of these protein kinases can play roles in the regulation of the mammalian cell cycle. The identification of a large family of cdc2-related kinases opens the possibility of combinatorial regulation of the cell cycle together with the emerging large family of cyclins.

FIZZ1, a novel cysteine-rich secreted protein associated with pulmonary inflammation, defines a new gene family

Bronchoalveolar lavage fluid from mice with experimentally induced allergic pulmonary inflammation contains a novel 9.4 kDa cysteine-rich secreted protein, FIZZ1 (found in inflammatory zone). Murine (m) FIZZ1 is the founding member of a new gene family including two other murine genes expressed, respectively, in intestinal crypt epithelium and white adipose tissue, and two related human genes. In control mice, FIZZ1 mRNA and protein expression occur at low levels in a subset of bronchial epithelial cells and in non-neuronal cells adjacent to neurovascular bundles in the peribronchial stroma, and in the wall of the large and small bowel. During allergic pulmonary inflammation, mFIZZ1 expression markedly increases in hypertrophic, hyperplastic bronchial epithelium and appears in type II alveolar pneumocytes. In vitro, recombinant mFIZZ1 inhibits the nerve growth factor (NGF)-mediated survival of rat embryonic day 14 dorsal root ganglion (DRG) neurons and NGF-induced CGRP gene expression in adult rat DRG neurons. In vivo, FIZZ1 may modulate the function of neurons innervating the bronchial tree, thereby altering the local tissue response to allergic pulmonary inflammation.

Maskless fabrication of light-directed oligonucleotide microarrays using a digital micromirror array

Oligonucleotide microarrays, also called "DNA chips," are currently made by a light-directed chemistry that requires a large number of photolithographic masks for each chip. Here we describe a maskless array synthesizer (MAS) that replaces the chrome masks with virtual masks generated on a computer, which are relayed to a digital micromirror array. A 1:1 reflective imaging system forms an ultraviolet image of the virtual mask on the active surface of the glass substrate, which is mounted in a flow cell reaction chamber connected to a DNA synthesizer. Programmed chemical coupling cycles follow light exposure, and these steps are repeated with different virtual masks to grow desired oligonucleotides in a selected pattern. This instrument has been used to synthesize oligonucleotide microarrays containing more than 76,000 features measuring 16 microm 2. The oligonucleotides were synthesized at high repetitive yield and, after hybridization, could readily discriminate single-base pair mismatches. The MAS is adaptable to the fabrication of DNA chips containing probes for thousands of genes, as well as any other solid-phase combinatorial chemistry to be performed in high-density microarrays.

Activation of cell-specific expression of rat growth hormone and prolactin genes by a common transcription factor

In the anterior pituitary gland, there are five phenotypically distinct cell types, including cells that produce either prolactin (lactotrophs) or growth hormone (somatotrophs). Multiple, related cis-active elements that exhibit synergistic interactions appear to be the critical determinants of the transcriptional activation of the rat prolactin and growth hormone genes. A common positive tissue-specific transcription factor, referred to as Pit-1, appears to bind to all the cell-specific elements in each gene and to be required for the activation of both the prolactin and growth hormone genes. The data suggest that, in the course of development, a single tissue-specific factor activates sets of genes that ultimately exhibit restricted cell-specific expression and define cellular phenotype.

Induction of the LIM homeobox gene Lmx1 by WNT7a establishes dorsoventral pattern in the vertebrate limb

During vertebrate limb development, the ectoderm directs the dorsoventral patterning of the underlying mesoderm. To define the molecular events involved in this process, we have analyzed the function of WNT7a, a secreted factor expressed in the dorsal ectoderm, and LMX1, a LIM homeodomain transcription factor expressed in the dorsal mesenchyme. Ectopic expression of Wnt7a is sufficient to induce and maintain Lmx1 expression in limb mesenchyme, both in vivo and in vitro. Ectopic expression of Lmx1 in the ventral mesenchyme is sufficient to generate double-dorsal limbs. Thus, the dorsalization of limb mesoderm appears to involve the WNT7a-mediated induction of Lmx1 in limb mesenchymal cells.

Direct cultivation of the causative agent of human granulocytic ehrlichiosis

BACKGROUND

Human granulocytic ehrlichiosis is a potentially fatal tick-borne infection that has recently been described. This acute febrile illness is characterized by myalgias, headache, thrombocytopenia, and elevated serum aminotransferase levels. The disease is difficult to diagnose because the symptoms are non-specific, intraleukocytic inclusions (morulae) may not be seen, and the serologic results are often initially negative. Little is known about the causative agent because it has never been cultivated.

METHODS

We studied three patients with symptoms and laboratory findings suggestive of human granulocytic ehrlichiosis, including unexplained fever after probable exposure to ticks, granulocytopenia, and thrombocytopenia. Peripheral blood was examined for ehrlichia microscopically and with use of the polymerase chain reaction (PCR). Blood was inoculated into cultures of HL60 cells (a line of human promyelocytic leukemia cells), and the cultures were monitored for infection by Giemsa staining and PCR.

RESULTS

Blood from the three patients, only one of whom had inclusions suggestive of ehrlichia in neutrophils, was positive for human granulocytic ehrlichiosis on PCR. Blood from all three patients was inoculated into HL60 cell cultures and caused infection, with intracellular organisms visualized as early as 5 days after inoculation and cell lysis occurring within 12 to 14 days. The identity of the cultured organisms was confirmed by immunofluorescence microscopy, PCR analysis, and DNA sequencing. DNA from the infected cells was sequenced in regions of the 16S ribosomal gene reported to differ between the agent of human granulocytic ehrlichiosis and closely related species, including Ehrlichia equi and E. phagocytophila which cause infection in animals. The sequences from all three human isolates were identical and differed from the strain of E. equi studied in having guanine rather than adenine at nucleotide 84.

CONCLUSIONS

We describe the cultivation of the agent of human granulocytic ehrlichiosis in cell culture. The ability to isolate this organism should lead to a better understanding of the biology, treatment, and epidemiology of this emerging infection.

Decreased food intake does not completely account for adiposity reduction after ob protein infusion

The effects of recombinantly produced ob protein were compared to those of food restriction in normal lean and genetically obese mice. Ob protein infusion into ob/ob mice resulted in large decreases in body and fat-depot weight and food intake that persisted throughout the study. Smaller decreases in body and fat-depot weights were observed in vehicle-treated ob/ob mice that were fed the same amount of food as that consumed by ob protein-treated ob/ob mice (pair feeding). In lean mice, ob protein infusion significantly decreased body and fat-depot weights, while decreasing food intake to a much lesser extent than in ob/ob mice. Pair feeding of lean vehicle-treated mice to the intake of ob protein-treated mice did not reduce body fat-depot weights. The potent weight-, adipose-, and appetite-reducing effects exerted by the ob protein in ob protein-deficient mice (ob/ob) confirm hypotheses generated from early parabiotic studies that suggested the existence of a circulating satiety factor of adipose origin. Pair-feeding studies provide compelling evidence that the ob protein exerts adipose-reducing effects in excess of those induced by reductions in food intake.

A pituitary POU domain protein, Pit-1, activates both growth hormone and prolactin promoters transcriptionally

The anterior pituitary gland provides a model for investigating the molecular basis for the appearance of phenotypically distinct cell types within an organ, a central question in development. The rat prolactin and growth hormone genes are expressed selectively in distinct cell types (lactotrophs and somatotrophs, respectively) of the anterior pituitary gland, reflecting differential mechanisms of gene activation or restriction, as a result of the interactions of multiple factors binding to these genes. We find that when the pituitary-specific 33-kD transcription factor Pit-1, expressed normally in both lactotrophs and somatotrophs, is expressed in either the heterologous HeLa cell line or in bacteria, it binds to and activates transcription from both growth hormone and prolactin promoters in vitro at levels even 10-fold lower than those normally present in pituitary cells. This suggests that a single factor, Pit-1, may be capable of activating the expression of two genes that define different anterior pituitary cell phenotypes. Because a putative lactotroph cell line (235-1) that does not express the growth hormone gene, but only the prolactin gene, appears to contain high levels of functional Pit-1, a mechanism selectively preventing growth hormone gene expression may, in part, account for the lactotroph phenotype.

Metabolites of dietary (soya) isoflavones in human urine

This study was undertaken to better understand the metabolic fate of dietary isoflavones in humans. Twelve volunteers were challenged with soya flour and urinary diphenol levels were then determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The presence of previously described urinary diphenols was confirmed, i.e. the isoflavones, daidzein and genistein; the isoflavonoid metabolites, equol, dihydrodaidzein (Int-O-D), O-desmethyl-angolensin (O-Dma); the lignan, enterolactone. Diphenols detected for the first time were the isoflavone, glycitein and five novel isoflavonoid metabolites which are tentatively identified as 6'-hydroxy-O-desmethylangolensin (6' OH-O-Dma), dihydrogenistein (Int-O-G), dehydro-O-desmethylangolensin (dehydro-O-Dma) and two isomers of tetrahydrodaidzein. Urinary excretion rates of the three isoflavones (daidzein, genistein, glycitein) over a 3-day period following soya challenge showed moderate variation (4x, 6x and 12x, respectively) between the 12 individuals suggesting some individual variabilities in ability to deconjugate and to absorb dietary isoflavones. However, urinary excretion rates of each of three major isoflavonoid metabolites (equol, O-Dma, 6' OH-O-Dma) showed more marked variation (922x, 17x, 15x, respectively); while some of this variability may reflect varying individual ability to ferment dietary isoflavones per se, an inverse relationship was found between urinary levels of equol and both O-Dma and 6' OH-O-Dma suggesting individual variability in the preferred metabolic pathways of dietary isoflavones.

Impact of white matter hyperintensity volume progression on rate of cognitive and motor decline

BACKGROUND

White matter hyperintensity (WMH) change on brain MRI is observed with increased frequency in the elderly and has been independently associated with neurologic decline. The degree to which the location and rate of volume increase in WMH affects other structural brain changes along with cognitive and motor performance over time may determine subsequent degrees of risk for dementia and other syndromes of aging.

METHODS

One hundred four cognitively intact men and women followed longitudinally for up to 13 years underwent at least three MRIs with corresponding annual cognitive and neurologic assessments. Brain volume, ventricular CSF (vCSF), and total periventricular (PV) and subcortical WMH volumes were measured. Progression of MRI volumes was examined in relation to rates of cognitive, motor, and cerebral volume change based on slopes of outcomes.

RESULTS

Higher initial total and PV WMH volume was associated with total WMH, PV WMH, and vCSF progression, and with increased time and number of steps to walk 30 feet. Progression of PV WMH volume was associated with increased time to walk 30 feet. Progression of subcortical WMH volume was associated with decreased performance on logical memory testing and increased rate of vCSF volume change.

CONCLUSION

Increased total and periventricular (PV) white matter hyperintensity (WMH) burden and progression of PV WMH burden are associated with decreased gait performance over time, while progression of subcortical WMH volume is associated with memory decline in cognitively intact elderly. Greater progression of WMH burden is associated with an increased risk of memory and gait dysfunction, and thus should not be considered a benign process.

A urinary profile study of dietary phytoestrogens. The identification and mode of metabolism of new isoflavonoids

The metabolic fate of the dietary isoflavones daidzein and genistein was investigated in human volunteers challenged with soya. Urinary diphenols, isolated by partition chromatography on Sephadex LH-20, were characterized and identified by profile capillary gas chromatography (GC) and electron ionization mass spectrometry (GC-EIMS) analysis of the trimethylsilyl ether (TMS) derivatives. Novel isoflavonic phytoestrogens found in the urine of volunteers were those of tetrahydrodaidzein, dihydrogenistein, 6'-hydroxy-O-demethylangolesin and 2-dehydro-O-demethylangolensin. Other known diphenols identified were those of equal, dehydrodaidzein, O-demethylangolensin, daidzein, genistein, glycitein, and the lignan enterolactone. Two other urinary isomers with a fragmentation pattern closely resembling that of the persilylated TMS ethers of cis/trans-isomers of tetrahydrodaidzein, were characterized based on the elucidation of fragments associated with the loss of a non-phenolic-OTMS functional group in ring-C. These are fragments presented in the persilylated mass spectra of isoflavan-4-ols and isoflav-3-ene-4-ols, demonstrated here by a combination of simple and tandem mass spectrometry study of the deuterated persilylated TMS ethers of dihydrodaidzein. In a similar study we also present the data on the structural identification and fragment elucidation of the keto/enol tautomers of the TMS ether derivatives of the dihydro derivatives of daidzein and genistein, observed in the urine of volunteers and considered probable products of the derivatization process. Finally, the GC and GC-MS data of two unknown isoflavonoids and that of a lignan-like compound are presented together with those of dihydrodaidzein, dihydrogenistein, tetrahydrodaidzein and 2-dehydro-O-demethylangolensin. The latter four were obtained here as products of small scale chemical synthesis in a preliminary study on the tentative identification of urinary isoflavonoids in human volunteers challenged with soya.

Effects of dietary cholesterol and fatty acids on plasma lipoproteins

The effects of dietary cholesterol and fatty acids on low density and high density lipoproteins (LDL and HDL) were studied in 20 young men. After 2-3 wk of evaluations on ad lib. diets, basal diets, which consisted of 15% protein, 45% carbohydrates, 40% fat, and 300 mg/day of cholesterol, were given for 4-5 wk (Basal). The ratio of dietary polyunsaturated to saturated fatty acids (P/S) for different groups of subjects were 0.25, 0.4, 0.8, or 2.5. 750 and 1,500 mg/d of cholesterol were added to the basal diets as 3 and 6 eggs, respectively. Total cholesterol and LDL cholesterol were lower in all subjects on the basal diets than on the ad lib. diets. Addition of 750 mg cholesterol to the diet with P/S = 0.25-0.4 raised LDL cholesterol by 16 +/- 14 mg/dl to 115% of basal diet values (n = 11, P less than 0.01); 1,500 mg increased LDL cholesterol by 25 +/- 19 mg/dl to 125% (n = 9, P less than 0.01). On the diet with P/S = 0.8, 750 mg produced insignificant increases in LDL cholesterol, but 1,500 mg produced increases of 17 +/- 22 mg/dl to 115% of basal (n = 6, P less than 0.02). On the P/S = 2.5 diet, neither 750 nor 1,500 mg produced significant changes. Thus, both the cholesterol contents and P/S ratios of diets were important in determining LDL levels. The lipid and apoprotein compositions, flotation rates, molecular weights, and binding by cellular receptors of LDL were virtually unchanged by the addition of cholesterol to the diets high in saturated fat. These diets, therefore, caused an increase in the number of LDL particles of virtually unchanged physical and biological properties. On the diet with low P/S ratio, HDL2 rose, whereas this effect was absent on diets with high P/S ratios. The response of LDL to dietary manipulations is consonant with epidemiologic data relating diets high in cholesterol and saturated fat to atherogenesis. The response of HDL2, however, is opposite to that of its putative role as a negative risk factor. Further work is needed to clarify this interesting paradox.

Generation and large-scale expansion of human inducible regulatory T cells that suppress graft-versus-host disease

Adoptive transfer of thymus-derived natural regulatory T cells (nTregs) effectively suppresses disease in murine models of autoimmunity and graft-versus-host disease (GVHD). TGFß induces Foxp3 expression and suppressive function in stimulated murine CD4+25- T cells, and these induced Treg (iTregs), like nTreg, suppress auto- and allo-reactivity in vivo. However, while TGFß induces Foxp3 expression in stimulated human T cells, the expanded cells lack suppressor cell function. Here we show that Rapamycin (Rapa) enhances TGFß-dependent Foxp3 expression and induces a potent suppressor function in naive (CD4+ 25-45RA+) T cells. Rapa/TGFß iTregs are anergic, express CD25 at levels higher than expanded nTregs and few cells secrete IL-2, IFNγ or IL-17 even after PMA and Ionomycin stimulation in vitro. Unlike other published methods of inducing Treg function, Rapa/TGFß induces suppressive function even in the presence of memory CD4+ T cells. A single apheresis unit of blood yields an average ~240 × 10⁹ (range ~ 70-560 × 10⁹) iTregs from CD4+25- T cells in ≤ 2 weeks of culture. Most importantly, Rapa/TGFß iTregs suppress disease in a xenogeneic model of GVHD. This study opens the door for iTreg cellular therapy for human diseases.

The variable metabolic response to dietary isoflavones in humans

The aim of this study was to better understand the metabolic fate of dietary estrogenic isoflavones in humans. Twelve volunteers were challenged with soya flour and urinary levels of the isoflavones daidzein (Da), genistein (Gen), and glycitein (Gly), and the isoflavonoid metabolites equol (Eq) and O-desmethylangolensin (O-Dma) determined by GC and GC-MS. Prior to challenge, Da, Gen, and Gly were present in the urine of all participants at low levels and Eq and O-Dma were present in 9/12 and 10/12 participants, respectively. Urinary levels of all five diphenols were increased in each individual on the day following challenge, returning to approximately prechallenge levels on the second or third day post-challenge. Mean post-challenge peak levels of the five diphenols compared with pre-challenge levels were Da (4x), Gen (8x), Gly (5x), Eq (45x), and O-Dma (66x). However, there was considerable individual variation in this metabolic response with peak levels of Eq showing the highest variation (1527x). An inverse relationship between Eq and O-Dma excretion was also found post-challenge suggesting individual variability in the preferred metabolic pathways of dietary isoflavones.

Pan: a transcriptional regulator that binds chymotrypsin, insulin, and AP-4 enhancer motifs

Two cDNAs were cloned that encode proteins (Pan-1 and Pan-2, with predicted molecular masses of 67.4 and 67.7 kD, respectively) that bind to a conserved transcriptional regulatory element present in pancreatic exocrine genes. The cDNAs are virtually identical in the region that encodes the amino-terminal 525 amino acids; they differ only by a 3-nucleotide insertion that results in the addition of a single amino acid. The cDNAs, however, code for related, but divergent, carboxy-terminal regions. Expression of the cloned cDNAs in HeLa cells activates expression of a cotransfected chimeric gene containing multimers of the pancreatic conserved element linked to a minimal promoter. Pan-1 and Pan-2 bind to the consensus sequence CAC/GCTGT/C, the CACCTGTC motif, which is present in transcriptional control elements of several genes. Both Pan-1 and Pan-2 bind to related motifs present in the rat insulin enhancer as well as a DNA segment containing the SV40 AP-4 element. The Pan-1 and Pan-2 cDNAs display extensive sequence identity with partial cDNA clones encoding E12 and E47, which bind to the immunoglobulin kappa E2 cis-active element, and may be derived from the same gene. These factors belong to a set of genetically distinct molecules, including AP-4 and MLTF, that bind to the CACCTGTC motif or related sequences. The Pan/E12,E47 proteins also show structural similarity with the Drosophila daughterless protein, MyoD, Myogenin, and Myf-5.

Discrete cis-active genomic sequences dictate the pituitary cell type-specific expression of rat prolactin and growth hormone genes

The anterior pituitary gland, which is derived from a common primordium originating in Rathke's pouch, contains phenotypically distinct cell types, each of which express discrete trophic hormones: adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), prolactin, growth hormone, and follicle stimulating hormone (FSH)/luteinizing hormone (LH). The structurally related prolactin and growth hormone genes, which are evolutionarily derived from a single primordial gene, are expressed in discrete cell types--lactotrophs and somatotrophs, respectively--with their expression virtually limited to the pituitary gland. The pituitary hormones exhibit a temporal pattern of developmental expression with rat growth hormone and prolactin characteristically being the last hormones expressed. The reported co-expression of these two structurally related neuroendocrine genes within single cells prior to the appearance of mature lactotrophs, in a subpopulation of mature anterior pituitary cells, and in many pituitary adenomas raises the possibility that the prolactin and growth hormone genes are developmentally controlled by a common factor(s). We now report the identification and characterization of nucleotide sequences in the 5'-flanking regions of the rat prolactin and growth hormone genes, respectively, which act in a position- and orientation-independent fashion to transfer cell-specific expression to heterologous genes. At least one putative trans-acting factor required for the growth hormone genomic sequence to exert its effects is apparently different from those modulating the corresponding enhancer element(s) of the prolactin gene because a pituitary 'lactotroph' cell line producing prolactin but not growth hormone selectively fails to express fusion genes containing the growth hormone enhancer sequence.

In vivo dopamine metabolism is altered in iron-deficient anemic rats

Previous studies of dopamine metabolism in iron-deficient rats demonstrated an elevation in extraneuronal levels of dopamine and a depression in the number of dopamine D2 receptors; however, the importance of anemia per se and the reversibility of these observations are not completely resolved. The purpose of this study was to determine if in vivo reuptake of caudate dopamine is altered by iron deficiency anemia, if it is reversible with iron therapy, and if anemia per se produced the same effects on dopamine metabolism. Male Sprague-Dawley rats (21-d old) were fed an iron-deficient diet (4 mg Fe/kg diet) and then iron repleted (5 mg iron dextran), or were fed an iron adequate diet (35 mg Fe/kg diet) and then given phenylhydrazine to induce hemolytic anemia. In vivo microdialysis was performed in steady-state conditions both before and after iron or no therapy and was followed by an intraperitoneal injection of a dopamine reuptake blocker (cocaine-HCl 30 mg/kg). Thirty percent higher extracellular dopamine levels in the caudate-putamen were observed in iron-deficient rats compared with control rats, but no differences were observed in tissue levels. Hemolytic anemic and iron-repleted rats had normal extracellular dopamine levels. The response to dopamine reuptake blockade was significantly attenuated in iron-deficient rats compared with control, iron-repleted, or hemolytic anemic rats. These experiments provide evidence that iron deficiency blunts the dopamine reuptake mechanism, that this is a reversible process in postweaning rats, and that anemia per se does not cause the increased extracellular dopamine levels.

Two related helix-loop-helix proteins participate in separate cell-specific complexes that bind the insulin enhancer

Cell-specific expression of the insulin gene is dependent on a conserved 8-basepair sequence, GCCATCTG, present in two copies in the 5' flanking DNA of the rat insulin 1 gene (Nir and Far elements). A protein factor with well characterized binding affinities binds to this sequence and is unique to the nuclei of insulin-producing cells. Using the Nir element as a probe to screen a hamster insulinoma cDNA expression library, we cloned two cDNA inserts that encode two related helix-loop-helix DNA-binding proteins: Syrian hamster Pan-1 (shPan-1) and Syrian hamster Pan-2 (shPan-2). These clones have minimal differences from the previously reported human E47/E12 and rat PAN (rPan) DNA-binding proteins. In vitro translated protein products of both clones bound the insulin gene promoter Nir and far elements as well as the E2 elements of the mu heavy chain and kappa light chain immunoglobulin genes. Treating insulinoma cell nuclear extract with antiserum selectively directed to each of the two shPan proteins demonstrated the presence of each form of shPan in separate DNA-binding complexes, which together form the previously described, cell-specific, Nir element-binding complex. We conclude that shPan-1 and shPan-2 are the hamster homologs of the ubiquitous E47/E12 and rPan proteins, but form parts of distinct DNA-binding complexes apparently found only in the nuclei of insulin-producing cells.

The burden of inherited leukodystrophies in children

OBJECTIVES

Leukodystrophies are diseases of the white matter for which data concerning clinical characteristics, incidence, disease burden, and description of outcomes are sparse. The purpose of our study was to determine the incidence and most common types of inherited leukodystrophies in a population, the mortality and time course of deaths, common neurologic features in patients, and health care costs associated with leukodystrophies.

METHODS

We conducted a retrospective, hospital- and clinic-based surveillance of inherited leukodystrophies among children younger than 18 years presenting to a regional children's hospital. We enrolled children evaluated from January 1, 1999, through December 31, 2007; clinical information was obtained from medical records. We calculated incidence based on state birth rates.

RESULTS

A total of 122 children with an inherited leukodystrophy were identified; 542 patients were excluded. A total of 49% had epilepsy, 43% required a gastrostomy tube, and 32% had a history of developmental regression. Mortality was 34%; average age at death was 8.2 years. No final diagnosis was reported in 51% of patients. The most common diagnoses were metachromatic leukodystrophy (8.2%), Pelizaeus-Merzbacher disease (7.4%), mitochondrial diseases (4.9%), and adrenoleukodystrophy (4.1%). Endocrine abnormalities and hypoplastic cerebellum were noted in significant portions of patients (15% and 14%). Average yearly per-patient medical costs were $22,579. Population incidence was 1 in 7,663 live births.

CONCLUSIONS

Inherited leukodystrophies are associated with substantial morbidity and mortality in children. Overall population incidence is higher than generally appreciated (1 in 7,663 live births). Most leukodystrophies remain undiagnosed, but a logical algorithm based on prevalence could aid testing.

A single domain of the estrogen receptor confers deoxyribonucleic acid binding and transcriptional activation of the rat prolactin gene

Binding of ligand to the estrogen receptor, a member of the steroid receptor gene family, rapidly increases PRL gene transcription. A 15 base pair core sequence 5'TTGTCACTATGTCCT-3' greater than 1.5 kilobase upstream from the rat PRL gene transcription start site is necessary for receptor binding, demonstrates interaction with the receptor DNA binding domain, and confers estrogen regulation. Transient cotransfection of expression plasmids encoding mutant estrogen receptors with a luciferase reporter plasmid under regulation of the rat PRL estrogen regulatory element were used to investigate the minimal information necessary and sufficient for activation of gene transcription. These analyses confirmed the absolute requirement for the receptor DNA binding domain in positive regulation of transcription, and revealed that removal of amino-terminal domains reduced, but did not abolish transcriptional effects. In contrast, truncation of the receptor immediately carboxy-terminal to the DNA binding domain resulted in constitutive activation of the receptor. The observations that removal of the steroid binding domain results in a constitutively active transcriptional factor, and that the amino-terminal domains are not required for transcriptional effect provides evidence that for two members of the steroid receptor gene family (the glucocorticoid and estrogen receptors), a relatively short DNA binding domain is sufficient for transcriptional activation. These results are likely to be prototypic for other members of this family of transcriptional factors.