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.

Myonuclear domains in muscle adaptation and disease

Adult skeletal muscle fibers are among the few cell types that are truly multinucleated. Recently, evidence has accumulated supporting a role for the modulation of myonuclear number during muscle remodeling in response to injury, adaptation, and disease. These studies have demonstrated that muscle hypertrophy is associated with, and is dependent on, the addition of newly formed myonuclei via the fusion of myogenic cells to the adult myofiber, whereas muscle atrophy and disease appear to be associated with the loss of myonuclei, possibly through apoptotic-like mechanisms. Moreover, these studies also have demonstrated that myonuclear domain size, i. e., the amount of cytoplasm per myonucleus, is unchanged following the acute phase of hypertrophy but is reduced following atrophy. Together these data demonstrate that modulation of myonuclear number or myonuclear domain size (or both) is a mechanism contributing to the remodeling of adult skeletal muscle in response to alterations in the level of normal neuromuscular activity.

Cardiac and skeletal muscle adaptations to voluntary wheel running in the mouse

In this paper, we describe the effects of voluntary cage wheel exercise on mouse cardiac and skeletal muscle. Inbred male C57/Bl6 mice (age 6-8 wk; n = 12) [corrected] ran an average of 4.3 h/24 h, for an average distance of 6.8 km/24 h, and at an average speed of 26.4 m/min. A significant increase in the ratio of heart mass to body mass (mg/g) was evident after 2 wk of voluntary exercise, and cardiac atrial natriuretic factor and brain natriuretic peptide mRNA levels were significantly increased in the ventricles after 4 wk of voluntary exercise. A significant increase in the percentage of fibers expressing myosin heavy chain (MHC) IIa was observed in both the gastrocnemius and the tibialis anterior (TA) by 2 wk, and a significant decrease in the percentage of fibers expressing IIb MHC was evident in both muscles after 4 wk of voluntary exercise. The TA muscle showed a greater increase in the percentage of IIa MHC-expressing fibers than did the gastrocnemius muscle (40 and 20%, respectively, compared with 10% for nonexercised). Finally, the number of oxidative fibers as revealed by NADH-tetrazolium reductase histochemical staining was increased in the TA but not the gastrocnemius after 4 wk of voluntary exercise. All results are relative to age-matched mice housed without access to running wheels. Together these data demonstrate that voluntary exercise in mice results in cardiac and skeletal muscle adaptations consistent with endurance exercise.

The environmental estrogen bisphenol A stimulates prolactin release in vitro and in vivo

Environmental estrogens (xenoestrogens) are a diverse group of chemicals that mimic estrogenic actions. Bisphenol A (BPA), a monomer of plastics used in many consumer products, has estrogenic activity in vitro. The pituitary lactotroph is a well established estrogen-responsive cell. The overall objective was to examine the effects of BPA on PRL release and explore its mechanism of action. The specific aims were to: 1) compare the potency of estradiol and BPA in stimulating PRL gene expression and release in vitro; 2) determine whether BPA increases PRL release in vivo; 3) examine if the in vivo estrogenic effects are mediated by PRL regulating factor from the posterior pituitary; and 4) examine if BPA regulates transcription through the estrogen response element (ERE). BPA increased PRL gene expression, release, and cell proliferation in anterior pituitary cells albeit at a 1000- to 5000-fold lower potency than estradiol. On the other hand, BPA had similar efficacy to estradiol in inducing hyperprolactinemia in estrogen-sensitive Fischer 344 (F344) rats; Sprague Dawley (SD) rats did not respond to BPA. Posterior pituitary cells from estradiol- or BPA-treated F344 rats strongly increased PRL gene expression upon coculture with GH3 cells stably transfected with a reporter gene. Similar to estradiol, BPA induced ERE activation in transiently transfected anterior and posterior pituitary cells. We conclude that: a) BPA mimics estradiol in inducing hyperprolactinemia in genetically predisposed rats; b) the in vivo action of estradiol and BPA in F344 rats is mediated, at least in part, by increasing PRL regulating factor activity in the posterior pituitary; c) BPA appears to regulate transcription through an ERE, suggesting that it binds to estrogen receptors in both the anterior and posterior pituitaries. The possibility that BPA and other xenoestrogens have adverse effects on the neuroendocrine axis in susceptible human subpopulations is discussed.

Apoptosis: a mechanism contributing to remodeling of skeletal muscle in response to hindlimb unweighting

The role of apoptosis in the elimination of myonuclei during hindlimb unloading-induced atrophy and the inhibition of apoptosis in the prevention of muscle atrophy were examined. The number of nuclei demonstrating double-stranded DNA fragmentation seen by terminal deoxynucleotidyl transferase (TDT) histochemical staining, an indicator of apoptosis, was significantly increased after 14 days of suspension. Double staining with TDT and antilaminin immunohistochemistry revealed that some TDT-positive nuclei were within the fiber lamina and were most likely myonuclei. The number of fibers containing morphologically abnormal nuclei was also significantly greater in suspended compared with control rats. Combined treatment with growth hormone and insulin-like growth factor I (GH/ IGF-I) and resistance exercise attenuated the increase in TDT-positive nuclei (approximately 26%, P > 0.05) and significantly decreased the number of fibers with morphologically abnormal nuclei. The data suggest that 1) "programmed nuclear death" contributes to the elimination of myonuclei and/or satellite cells from atrophying fibers, and 2) GH/IGF-I administration plus muscle loading ameliorates the apoptosis associated with hindlimb unloading.

Antibody engineering for the analysis of affinity maturation of an anti-hapten response

The influence of structural variation, previously observed in a panel of V186.2 VH/V lambda 1-expressing anti-NP antibodies from the secondary response, on the affinity of these antibodies was examined by site-specific mutagenesis and recombinant antibody construction. A tryptophan----leucine exchange at position 33 in the VH segment of all but one of the high-affinity antibodies is the most frequently observed somatic mutation and by itself leads to a 10-fold higher affinity; all other somatic exchanges are irrelevant for affinity selection. In the single case of a high-affinity antibody without this common exchange, high affinity is mediated by a combination of mutations (including a one-codon deletion) in VH and the particular D-JH rearrangement carried by this antibody. The data indicate that the pattern of somatic diversification through hypermutation is shaped by affinity selection, but that only a single point mutation is available in the VH and the VL gene of lambda 1 chain-bearing anti-NP antibodies which by itself leads to an increase of hapten-binding affinity. Based on the analysis of two secondary response antibodies from which somatic mutations in VH and VL have been eliminated, it is also concluded that the recruitment of B cell clones into the pathway of hypermutation involves a mechanism which is not based upon affinity differences towards the antigen.

Effects of steroids and retinoids on wound healing

HYPOTHESIS

Anti-inflammatory corticosteroids significantly impair wound healing. Retinoids partially, but significantly, reverse this effect. Little is known about the mechanism of steroid retardation or retinoid reversal. We hypothesized that corticosteroids lower transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) levels and tissue deposition in wounds and that retinoids stimulate corticosteroid-impaired TGF-beta and IGF-I release and collagen production.

DESIGN

Randomized controlled trial.

SETTING

Wound healing research laboratory.

PARTICIPANTS

Animal study.

INTERVENTIONS

Four wire mesh wound cylinders were implanted subcutaneously into the backs of 72 male Sprague-Dawley rats. Wound healing was impaired by a single subcutaneous injection of 6 mg of methylprednisolone acetate (Depo-Medrol). Two preparations of retinoids were used in separate experiments: all-trans-retinoic acid and 9-cis-retinoic acid that were fed orally.

MAIN OUTCOME MEASURES

Hydroxyproline content was measured in the healing tissue and TGF-beta and IGF-I levels were analyzed in the wound fluid.

RESULTS

Methylprednisolone treatment significantly decreased TGF-beta and IGF-I levels in the wound fluid and hydroxyproline content in the tissue (P<.05). Oral all-trans- and 9-cis-retinoic acid partially reversed the TGF-beta and IGF-I decrease and significantly increased hydroxyproline content toward normal levels (P<.05). Oral all-trans-retinoic acid enhanced collagen deposition, TGF-beta and IGF-I levels over normal chow fed control animals (P<.05).

CONCLUSIONS

Steroids and retinoids have antagonistic effects on growth factors and collagen deposition in wound healing. These effects can be relevant for treatment options in a clinical setting.

Predictors and correlates of adaptive functioning in children with developmental disorders

Autism is a developmental disorder marked by impairments in socialization, communication, and perseverative behavior and is associated with cognitive impairment and deficits in adaptive functioning. Research has consistently demonstrated that children with autism have deficits in adaptive functioning more severe than their cognitive deficits. This study investigates the correlates and predictors of adaptive functioning as measured by the Vineland Adaptive Behavior Scales in high- and low-functioning children with autism and their age and nonverbal IQ matched controls. Thirty-five 9-year-old children with high-functioning autism (HAD) were compared with 31 age-matched children with developmental language disorder (DLD), and 40 9-year-old children with low-functioning autism (LAD) were compared with 17 age-matched children with low IQ on adaptive functioning, IQ, autistic symptomology, and tests of language and verbal memory. Results indicate that both groups with autism were significantly impaired compared to their matched controls on Socialization and Daily Living, but not Communication and that these impairments were more pronounced in the HAD group than in the LAD group. Adaptive behavior was strongly correlated with autistic symptomology only in the HAD group. Regression analyses indicated that IQ was strongly predictive of adaptive behavior in both low-functioning groups, but tests of language and verbal memory predicted adaptive behavior in the higher functioning groups. Results suggest that IQ may act as a limiting factor for lower functioning children but higher functioning children are impaired by specific deficits, including autistic symptomology and impaired language and verbal memory.

A circadian enhancer mediates PER-dependent mRNA cycling in Drosophila melanogaster

Genes expressed under circadian-clock control are found in organisms ranging from prokaryotes to humans. In Drosophila melanogaster, the period (per) gene, which is required for clock function, is transcribed in a circadian manner. We have identified a circadian transcriptional enhancer within a 69-bp DNA fragment upstream of the per gene. This enhancer drives high-amplitude mRNA cycling under light-dark-cycling or constant-dark conditions, and this activity is per protein (PER) dependent. An E-box sequence within this 69-bp fragment is necessary for high-level expression, but not for rhythmic expression, indicating that PER mediates circadian transcription through other sequences in this fragment.

Timing, genetic requirements and functional consequences of somatic hypermutation during B-cell development

While somatic antibody mutants are rare in the preimmune repertoire and in primary immune responses, they dominate secondary and hyperimmune responses. We present evidence that somatic hypermutation is restricted to a particular pathway of B-cell differentiation in which distinct sets of B-cell clones are driven into the memory compartment. In accord with earlier results of McKean et al. (1984) and Rudikoff et al. (1984), somatic mutation occurs stepwise in the course of clonal expansion, before and after isotype switch, presumably at a rate close to 1 X 10(-3) per base pair per generation. At this rate, both selectable and unselectable mutations accumulate in the rearranged V region genes. The distribution of replacement mutations in the V regions shows that a fraction of the mutations in CDRs is positively selected whereas replacement mutations are counterselected in the FRs. By constructing an antibody mutant through site-specific mutagenesis we show that a point mutation in CDR1 of the heavy chain, found in most secondary anti-NP antibodies, is sufficient to increase NP binding affinity to the level typical for the secondary response. Somatic mutation may contribute to the immune repertoire in a more general sense than merely the diversification of a specific response. We have evidence that clones producing antibodies which no longer bind the immunizing antigen can be kept in the system and remain available for stimulation by a different antigen. Somatic mutations are 10 times less frequent in DJH loci than in either expressed or non-expressed rearranged VDJH or VJ loci. We therefore conclude that a V gene has to be brought into the proximity of the DJH segment in order to fully activate the hypermutational mechanism in these loci.

Laparoscopy during pregnancy

OBJECTIVE

To compare the safety and efficacy of laparoscopic surgery with that of open laparotomy in pregnant patients.

DESIGN

Six-year case-control study.

SETTING

Tertiary care, university and community hospitals.

PATIENTS

Population-based sample. From 1990 through 1995, 16 pregnant patients underwent laparoscopic surgery (study group) and 18 underwent open laparotomy (control group) during the first or second trimester. Follow-up ranged from 1 month to 6 years.

INTERVENTION

In the study group, 4 patients underwent appendectomies and 12 underwent cholecystectomies. The control group included 7 appendectomies and 11 cholecystectomies.

MAIN OUTCOME MEASURES

The 2 groups were compared for age, trimester, surgical time, oxygen saturation, end-tidal carbon dioxide, return of gastrointestinal tract function, duration of intravenous or intramuscular narcotics, postoperative stay, gestational age of delivery, 1- and 5-minute Apgar scores, birth weights, and complications.

RESULTS

Age, trimester, oxygenation, end-tidal CO2, gestational age at delivery, Apgar scores, and birth weights were not different between the 2 groups. The patients who underwent laparoscopy had significantly longer operative times 82 vs 49 minutes), shorter stay (1.5 vs 2.8 days), earlier resumption of regular diet (1.0 vs 2.4 days), and shorter duration of intravenous or intramuscular narcotics (1.2 vs 2.6 days) (all P < .01). Four complications were found in the laparotomy group vs 6 in the laparoscopy group.

CONCLUSIONS

Laparoscopic surgery in pregnant women significantly decrease hospitalization, decreases narcotic use, and quickens return to a regular diet when compared with open laparotomy in pregnant women. No significant differences between the 2 groups in perioperative morbidity or mortality were present. These data suggest that therapeutic laparoscopy during pregnancy in the first or second trimester is safe.

Challenging behaviours: prevalence and topographies

BACKGROUND

Variations in reported prevalence of challenging behaviour indicate the need for further epidemiological research to support accurate planning of future service provision.

METHODS

All services providing for people with learning disabilities across seven unitary authorities, with a total population of 1.2 million, were screened to identify people with challenging behaviour. Interviews were conducted with primary carers to gain data on identified individuals' characteristics and support. Measures designed for a similar study conducted in Manchester University were incorporated to allow direct comparison with earlier findings, together with standardized tools to assess adaptive behaviour and social impairment.

RESULTS

In total, 4.5 (2.5-7.5) people per 10 000 population were rated as seriously challenging, representing 10% (5.5-16.8%) of the learning disability population; the most prevalent general form was other difficult/disruptive behaviour, with non-compliance being the most prevalent topography. The majority showed multiple behaviours and multiple topographies within each general behaviour category. Also identified were substantial numbers of additional people reported as presenting challenging behaviours at lower degrees of severity.

CONCLUSIONS

Prevalence rates for seriously challenging behaviours were comparable to those reported in the earlier studies, thus confirming previous findings. The prevalence of less serious challenging behaviour also has major clinical significance and emphasizes the need for enhanced understanding and skills among personnel within primary- and secondary-tier health, education and social care services, and for strengthening the capacity of community teams to provide behavioural expertise.

Plasticity of myonuclear number in hypertrophied and atrophied mammalian skeletal muscle fibers

Although a mammalian skeletal muscle fiber may contain thousands of myonuclei, the importance of this number or the potential to modulate it in adult muscle has not been clearly demonstrated. Using immunohistochemistry and confocal microscopy, we examined the plasticity of myonuclear number and fiber size in isolated fast and slow fiber segments from adult cat hindlimb muscles in response to chronic alterations in neuromuscular activity and loading. Compared with slow fibers in the soleus of control cats, myonuclear number in presumably transformed fast fibers was 32% lower and fiber size was decreased 73% after elimination of neuromuscular activation for 6 mo by spinal isolation. Slow fibers in the soleus of spinal-isolated cats had smaller cross-sectional areas, whereas myonuclear number was not significantly different than that in the control cats. Myonuclear number in fast plantaris fibers was more than threefold higher and fiber size was 2.8-fold higher after 3 mo of functional overload compared with the plantaris of control cats. Compared with control slow plantaris fibers, myonuclear number and fiber size also increased in overloaded slow plantaris fibers. These results demonstrate that changes in myonuclear number are associated with changes in myosin type and suggest that modulations in the amount of available DNA may be a factor in regulating cytoplasmic volume of muscle fibers in response to chronic changes in neuromuscular activity.

The xenoestrogen bisphenol A induces growth, differentiation, and c-fos gene expression in the female reproductive tract

The xenoestrogen bisphenol A (BPA) has been shown to mimic estrogen both in vivo and in vitro. BPA stimulates PRL secretion and the expression of a PRL regulating factor from the posterior pituitary in the estrogen-sensitive Fischer 344 rat (F344), but not in Sprague-Dawley (SD) rats. The goal of the present studies was to examine the in vivo actions of BPA on the reproductive tract. The specific objectives were 1) to characterize the short term effects of BPA on cell proliferation and c-fos expression in the uterus and vagina, and 2) to compare the effects of prolonged exposure to low doses of BPA on the reproductive tract of F344 and SD rats. Treatment with single high doses of BPA induced cell proliferation in the uterus and vagina of ovariectomized F344 rats, as determined by bromodeoxyuridine immunostaining. This proliferation was dose dependent (from 37.5-150 mg/kg) and followed a time course similar to that of estradiol (E2). Quantitative RT-PCR revealed that both BPA and E2 increased c-fos messenger RNA levels in the uterus 14- to 16-fold within 2 h, which returned to basal levels after 6 h. In the vagina, BPA-induced c-fos expression remained elevated for up to 6 h, compared with the transient increase caused by E2. Treatment of F344 rats for 3 days with continuous release capsules that supplied a much lower dose of BPA (approximately 0.3 mg/kg x day) resulted in hypertrophy, hyperplasia, and mucus secretion in the uterus and hyperplasia and cornification of the vaginal epithelium. The reproductive tract of SD rats did not respond to this treatment paradigm with BPA. These studies demonstrate that 1) the molecular and morphological alterations induced by BPA in the uterus and vagina are nearly identical to those induced by estradiol; 2) the vagina appears to be especially sensitive to the estrogenic actions of BPA; 3) the reproductive tract of the inbred F344 rat appears more sensitive to BPA than that of the outbred SD rat; and 4) continuous exposure to microgram levels of BPA is sufficient for exerting estrogenic actions.

Myonuclear number and myosin heavy chain expression in rat soleus single muscle fibers after spaceflight

The effects of 14 days of spaceflight on myonuclear number, fiber size, and myosin heavy chain (MHC) expression in isolated rat soleus muscle fiber segments were studied. Single soleus muscle fibers from rats flown on the Spacelab Life Sciences-2 14-day mission were compared with those from age-matched ground-based control rats by using confocal microscopy and gel electrophoresis. Spaceflight resulted in a significant reduction in the number of fibers expressing type I MHC and an increase in the number of fibers expressing type IIx or IIa MHC. Space-flight also resulted in an increase in the percentage of fibers coexpressing more than one MHC and in the reexpression of the neonatal isoform of MHC in some fibers. Fiber cross-sectional area was significantly reduced in pure type I MHC-expressing fibers and in fibers coexpressing type I+II MHC but not in fibers expressing one or more type II MHC in the flight rats. The number of myonuclei per millimeter was significantly reduced in type I MHC-expressing fibers from the flight rats but was not significantly different in type I+II and type II MHC-coexpressing fibers. Fibers expressing neonatal MHC were similar in size to control fibers but had significantly fewer myonuclei per millimeter than flight fibers not expressing neonatal MHC. In type I MHC-expressing fibers, the reduction in fiber cross-sectional area was greater than the reduction in myonuclear number; thus the average cytoplasmic volume per myonucleus was significantly lower in flight than in control fibers. The reduction in both myonuclear number and fiber size of fibers expressing type I MHC after 14 days of spaceflight supports the hypothesis that changes in the number of myonuclei may be a contributing factor to the reduction in fiber size associated with chronic unloading of the musculature.

Osmolyte-induced changes in protein conformational equilibria

Examining solute-induced changes in protein conformational equilibria is a long-standing method for probing the role of water in maintaining protein stability. Interpreting the molecular details governing the solute-induced effects, however, remains controversial. We present experimental and theoretical data for osmolyte-induced changes in the stabilities of the A and N states of yeast iso-1-ferricytochrome c. Using polyol osmolytes of increasing size, we observe that osmolytes alone induce A-state formation from acid-denatured cytochrome c and N state formation from the thermally denatured protein. The stabilities of the A and N states increase linearly with osmolyte concentration. Interestingly, osmolytes stabilize the A state to a greater degree than the N state. To interpret the data, we divide the free energy for the reaction into contributions from nonspecific steric repulsions (excluded volume effects) and from binding interactions. We use scaled particle theory (SPT) to estimate the free energy contributions from steric repulsions, and we estimate the contributions from water-protein and osmolyte-protein binding interactions by comparing the SPT calculations to experimental data. We conclude that excluded volume effects are the primary stabilizing force, with changes in water-protein and solute-protein binding interactions making favorable contributions to stability of the A state and unfavorable contributions to the stability of the N state. The validity of our interpretation is strengthened by analysis of data on osmolyte-induced protein stabilization from the literature, and by comparison with other analyses of solute-induced changes in conformational equilibria.

Different pathways regulate expression of the skeletal myosin heavy chain genes

Mammalian skeletal muscles are a mosaic of different fiber types largely defined by differential myosin heavy chain (MyHC) expression. Little is known about the molecular mechanisms regulating expression of the MyHC gene family members in different fiber types. In this work, we identified several cis- and trans-elements that regulate expression of the three adult fast MyHC genes. Despite multiple DNA-binding motifs for well characterized muscle transcription factors upstream of all three fast MyHC genes, expression of MyoD/Myf-5, calcineurin, or NFAT3 had different effects on the three promoters. MyoD or Myf-5 overexpression preferentially activated the IIb promoter, whereas NFAT or activated calcineurin overexpression preferentially activated the IIa promoter. Calcineurin had a 50-100-fold stimulatory effect on the IIa promoter, and the known downstream effectors of calcineurin (myocyte enhancer factor-2 and NFAT) cannot completely account for this activation. Finally, we identified two elements critical for regulating MyHC-IId/x expression: a 130-base pair enhancer element and a CArG-like element that inhibited IId/x promoter activity in vitro. Thus, we have found specific regulatory pathways that are distinct for the three adult fast MyHC genes. These elements are logical candidates for fiber-specific control of skeletal muscle gene expression in vivo.

Development of serine protease inhibitors displaying a multicentered short (<2.3 A) hydrogen bond binding mode: inhibitors of urokinase-type plasminogen activator and factor Xa

Novel scaffolds that bind to serine proteases through a unique network of short hydrogen bonds to the catalytic Ser195 have been developed. The resulting potent serine protease inhibitors were designed from lead molecule 2-(2-hydroxyphenyl)1H-benzoimidazole-5-carboxamidine, 6b, which is known to display several modes of binding. For instance, 6b can recruit zinc and bind in a manner similar to that reported by bis(5-amidino-2-benzimidazolyl)methane (BABIM) (Nature 1998, 391, 608-612).(1) Alternatively, 6b can bind in the absence of zinc through a multicentered network of short (<2.3 A) hydrogen bonds. The lead structure was optimized in the zinc-independent binding mode toward a panel of six human serine proteases to yield optimized inhibitors such as 2-(3-bromo-2-hydroxy-5-methylphenyl)-1H-indole-5-carboxamidine, 22a, and 2-(2-hydroxybiphenyl-3-yl)-1H-indole-5-carboxamidine, 22f. Structure-activity relationships determined that, apart from the amidine function, an indole or benzimidazole and an ortho substituted phenol group were also essential components for optimal potency. The affinities (K(i)) of 22a and 22f, for example, bearing these groups ranged from 8 to 600 nM toward a panel of six human serine proteases. High-resolution crystal structures revealed that the binding mode of these molecules in several of the enzymes was identical to that of 6b and involved short (<2.3 A) hydrogen bonds among the inhibitor hydroxyl oxygen, Ser195, and a water molecule trapped in the oxyanion hole. In summation, novel and potent trypsin-like serine protease inhibitors possessing a unique mode of binding have been discovered.

Subgroups of children with autism by cluster analysis: a longitudinal examination

OBJECTIVES

A hierarchical cluster analysis was conducted using a sample of 138 school-age children with autism. The objective was to examine (1) the characteristics of resulting subgroups, (2) the relationship of these subgroups to subgroups of the same children determined at preschool age, and (3) preschool variables that best predicted school-age functioning.

METHOD

Ninety-five cases were analyzed.

RESULTS

Findings support the presence of 2 subgroups marked by different levels of social, language, and nonverbal ability, with the higher group showing essentially normal cognitive and behavioral scores. The relationship of high- and low-functioning subgroup membership to levels of functioning at preschool age was highly significant.

CONCLUSIONS

School-age functioning was strongly predicted by preschool cognitive functioning but was not strongly predicted by preschool social abnormality or severity of autistic symptoms. The differential outcome of the 2 groups shows that high IQ is necessary but not sufficient for optimal outcome in the presence of severe language impairment.

Modulation of myonuclear number in functionally overloaded and exercised rat plantaris fibers

The effects of 10 wk of functional overload (FO), with and without daily treadmill endurance training, on the cross-sectional area, myonuclear number, and myonuclear domain size of mechanically isolated single fiber segments of the adult rat plantaris were determined. The fibers were typed on the basis of high-resolution gel electrophoresis for separation of specific myosin heavy chain (MHC) isoforms and grouped as type I(+) (containing some type I MHC with or without any combination of fast MHCs), type IIa(+) (containing some type IIa with or without some type IIx and/or IIb but no type I MHC), and type IIx/b (containing only type IIx and/or IIb MHCs). Type I(+) fibers had a higher myonuclear number than did both fast types of fibers in the control and FO, but not in the FO and treadmill trained, rats. All fiber types in both FO groups had a significantly larger (36-90%) cross-sectional area and a significantly higher (61-109%) myonuclear number than did control. The average myonuclear domain size of each fiber type was similar among the three groups, except for a smaller domain size in the type IIx/b fibers of the FO compared with control. In general, these data indicate that during hypertrophy the number of myonuclei increase proportionally to the increase in fiber volume. The maintenance of myonuclear domain size near control values suggests that regulatory mechanisms exist that ensure a tight coupling between the quantity of genetic machinery and the protein requirements of a fiber.

Phantom limb pain and residual limb pain following lower limb amputation: a descriptive analysis

PURPOSE

This research aimed to develop a clearer picture of the experience of residual limb pain and phantom limb pain following a lower limb amputation and to gain a greater understanding of their relationships with physical and psychosocial variables.

METHOD

One hundred and four participants completed the Trinity Amputation and Prosthesis Experience Scales (TAPES), which includes a section on each of, psychosocial issues, activity restriction, satisfaction with a prosthesis and pain (incidence, duration, level and extent of interference).

RESULTS

The results showed that 48.1% of the sample experienced residual limb pain and 69.2% experienced phantom limb pain. While fewer people experienced residual limb pain, those who did, experienced it for longer periods, at a greater level of intensity and with a greater amount of interference in their daily lifestyle, than people who were experiencing phantom limb pain. The experience of residual limb pain was associated with other medical problems and low levels of Adjustment to Limitation. Phantom limb pain was associated with older age, being female, above knee amputation, causes other than congenital causes, not receiving support prior to the amputation, the experience of other medical problems, low scores on Adjustment to Limitation and high scores on Aesthetic Satisfaction with the prosthesis.

CONCLUSION

These findings provide a greater understanding of the issues to be taken into consideration in the rehabilitation of people with a lower limb amputation.

Growth of severely impaired children: neurological versus nutritional factors

Nineteen children with cerebral palsy who have had gastrostomies since 1981 and who have been followed for at least six months postoperatively were reviewed to assess the effects of gastrostomy feeding on their growth and to determine whether growth failure was due to neurological or nutritional dysfunction. The children's ages ranged from five to 168 months (mean 60.4 months) and follow-up extended from six to 41 months (mean 23.1 months). All were profoundly handicapped, with involvement of all four limbs. 11 also had seizures and all 19 were severely to profoundly retarded. Heights and weights were recorded during the visit immediately before surgery and at most recent follow-up. Data were recorded as a standard deviation score (Z-score). Before surgery the mean weight/height was -2.71 Z. Postoperatively this improved to -1.18 Z. 16 of the 19 children increased their weight/height ratio. Three children had a weight/height ratio greater than 10th percentile preoperatively. 11 achieved this on follow-up. Seven children were greater than 25th percentile for weight/height. Improvement in weight/height did not correlate with length of follow-up. For severely neurologically impaired children, nutritional factors play a major rôle in growth. By ensuring adequate caloric intake via gastrostomy, a significant number of children achieved adequate growth and better nutritional status.

Vitronectin stabilizes thrombi and vessel occlusion but plays a dual role in platelet aggregation

The role of vitronectin (Vn) in thrombosis is currently controversial; both inhibitory and supportive roles have been reported. To monitor directly the function of Vn in thrombotic events at the site of vascular injury, we studied Vn-deficient (Vn-/-) and wild-type (WT) control mice with two real-time intravital microscopy thrombosis models. In the mesenteric arteriole model, vessel injury was induced by ferric chloride. We observed unstable thrombi and a significantly greater number of emboli in Vn-/- mice. Vessel occlusion was also delayed and frequent vessel re-opening occurred. In the cremaster muscle arteriole model, vessel injury was induced by a nitrogen dye laser. We observed significantly fewer platelets, lower fibrin content, and unstable fibrin within the thrombi of Vn-/- mice. To define further the role of Vn in thrombus growth, we studied platelet aggregation in vitro. Consistent with our in vivo data, the second wave of thrombin-induced aggregation of gel-filtered platelets was abolished at a low concentration of thrombin in Vn-/- platelets. Interestingly, adenosine diphosphate (ADP)-induced platelet aggregation was significantly increased in Vn-/- platelet-rich plasma (PRP) and this effect was attenuated by adding purified plasma Vn. We also observed increased platelet aggregation induced by shear stress in Vn-/- whole blood. These data demonstrate that Vn is a thrombus stabilizer. However, in contrast to released platelet granule Vn which enhances platelet aggregation, plasma Vn inhibits platelet aggregation.