Transgenic overexpression of cardiac actin in the mouse heart suggests coregulation of cardiac, skeletal and vascular actin expression

Previous studies have shown that depletion of cardiac actin by targeted disruption is associated with increased expression of alternative actins in the mouse heart. Here we have studied the effects of transgenic overexpression of cardiac actin using the alpha-myosin heavy chain promoter. Lines carrying 7 or 8 copies of the transgene showed a 2-fold increase in cardiac actin mRNA and also displayed decreased expression of skeletal and vascular actin in their hearts. In contrast, a line with more than 250 copies of the transgene did not show a similar decrease in the expression of skeletal and vascular actin despite a 3-fold increase in cardiac actin mRNA. While the low copy number transgenic mice displayed hearts that were similar to non-transgenic controls, the high copy number transgenic line showed larger hearts with distinct atrial enlargement and cardiomyocyte hypertrophy. Further, while the low copy number transgenic mouse hearts were mildly hypocontractile when compared with non-transgenic mouse hearts, the high copy number transgenic mouse hearts were significantly so. We conclude that in the presence of a small number of copies of the cardiac actin transgene, homeostatic mechanisms involved in maintaining actin levels are active and negatively regulate skeletal and vascular actin levels in the heart in response to increased expression of cardiac actin. However, these putative mechanisms are either inoperative in the high copy number transgenic line or are countered by the enhanced expression of skeletal and vascular actin during cardiomyocyte hypertrophy.

Setting the stage: developmental biology in pre-college classrooms

Exercises that employ dynamic living material have proved highly successful at generating interest in science among young students. Developing embryos and larvae are especially well suited for such endeavors, for they can be handled without expensive or elaborate equipment, and their changing nature engages students. Using amphibian embryos, which are relatively large and exhibit profound, easily observed morphological changes, and amphibian larvae, which are easily kept and observed, captures the attention of children. By designing inquiry-based exercises and focused discussion sessions, a high intellectual content can be integrated into these endeavors. The long-term implications for generating an informed citizenry, improving the participation of women in science, and empowering elementary school teachers are profound. Professional developmental biology researchers should feel encouraged to participate in these types of activities.

Mice lacking skeletal muscle actin show reduced muscle strength and growth deficits and die during the neonatal period

All four of the muscle actins (skeletal, cardiac, vascular, and enteric) in higher vertebrates show distinct expression patterns and display highly conserved amino acid sequences. While it is hypothesized that each of the muscle isoactins is specifically adapted to its respective tissue and that the minor variations among them have developmental and/or physiological relevance, the exact functional and developmental significance of these proteins remains largely unknown. In order to begin to assess these issues, we disrupted the skeletal actin gene by homologous recombination. All mice lacking skeletal actin die in the early neonatal period (day 1 to 9). These null animals appear normal at birth and can breathe, walk, and suckle, but within 4 days, they show a markedly lower body weight than normal littermates and many develop scoliosis. Null mice show a loss of glycogen and reduced brown fat that is consistent with malnutrition leading to death. Newborn skeletal muscles from null mice are similar to those of wild-type mice in size, fiber type, and ultrastructural organization. At birth, both hemizygous and homozygous null animals show an increase in cardiac and vascular actin mRNA in skeletal muscle, with no skeletal actin mRNA present in null mice. Adult hemizygous animals show an increased level of skeletal actin mRNA in hind limb muscle but no overt phenotype. Extensor digitorum longus (EDL) muscle isolated from skeletal-actin-deficient mice at day 2 to 3 showed a marked reduction in force production compared to that of control littermates, and EDL muscle from hemizygous animals displayed an intermediate force generation. Thus, while increases in cardiac and vascular smooth-muscle actin can partially compensate for the lack of skeletal actin in null mice, this is not sufficient to support adequate skeletal muscle growth and/or function.

Genes for the biosynthesis of spinosyns: applications for yield improvement in Saccharopolyspora spinosa

Spinosyns A and D are the active ingredients in an insect control agent produced by fermentation of Saccharopolyspora spinosa. Spinosyns are macrolides with a 21-carbon, tetracyclic lactone backbone to which the deoxysugars forosamine and tri-O-methylrhamnose are attached. The spinosyn biosynthesis genes, except for the rhamnose genes, are located in a cluster that spans 74 kb of the S. spinosa genome. DNA sequence analysis, targeted gene disruptions and bioconversion studies identified five large genes encoding type I polyketide synthase subunits, and 14 genes involved in sugar biosynthesis, sugar attachment to the polyketide or cross-bridging of the polyketide. Four rhamnose biosynthetic genes, two of which are also necessary for forosamine biosynthesis, are located outside the spinosyn gene cluster. Duplication of the spinosyn genes linked to the polyketide synthase genes stimulated the final step in the biosynthesis--the conversion of the forosamine-less pseudoaglycones to endproducts. Duplication of genes involved in the early steps of deoxysugar biosynthesis increased spinosyn yield significantly.

Macrophage tropism of human immunodeficiency virus type 1 isolates from brain and lymphoid tissues predicts neurotropism independent of coreceptor specificity

The viral determinants that underlie human immunodeficiency virus type 1 (HIV-1) neurotropism are unknown, due in part to limited studies on viruses isolated from brain. Previous studies suggest that brain-derived viruses are macrophage tropic (M-tropic) and principally use CCR5 for virus entry. To better understand HIV-1 neurotropism, we isolated primary viruses from autopsy brain, cerebral spinal fluid, blood, spleen, and lymph node samples from AIDS patients with dementia and HIV-1 encephalitis. Isolates were characterized to determine coreceptor usage and replication capacity in peripheral blood mononuclear cells (PBMC), monocyte-derived macrophages (MDM), and microglia. Env V1/V2 and V3 heteroduplex tracking assay and sequence analyses were performed to characterize distinct variants in viral quasispecies. Viruses isolated from brain, which consisted of variants that were distinct from those in lymphoid tissues, used CCR5 (R5), CXCR4 (X4), or both coreceptors (R5X4). Minor usage of CCR2b, CCR3, CCR8, and Apj was also observed. Primary brain and lymphoid isolates that replicated to high levels in MDM showed a similar capacity to replicate in microglia. Six of 11 R5 isolates that replicated efficiently in PBMC could not replicate in MDM or microglia due to a block in virus entry. CD4 overexpression in microglia transduced with retroviral vectors had no effect on the restricted replication of these virus strains. Furthermore, infection of transfected cells expressing different amounts of CD4 or CCR5 with M-tropic and non-M-tropic R5 isolates revealed a similar dependence on CD4 and CCR5 levels for entry, suggesting that the entry block was not due to low levels of either receptor. Studies using TAK-779 and AMD3100 showed that two highly M-tropic isolates entered microglia primarily via CXCR4. These results suggest that HIV-1 tropism for macrophages and microglia is restricted at the entry level by a mechanism independent of coreceptor specificity. These findings provide evidence that M-tropism rather than CCR5 usage predicts HIV-1 neurotropism.

Emerging role of the pediatric nurse practitioner in acute care

The pediatric nurse practitioner role in the tertiary setting is one of several emerging roles gaining recognition in the various groups of advanced practice nursing programs today. The advanced practice nurse (APN) who is a pediatric nurse practitioner (PNP) in an acute care setting helps to provide cost-effective, quality patient care for critically and chronically ill children who are in these settings. The foundation of advanced practice nursing in this role incorporates the general role expectations of advanced nursing preparation, including case management, clinical pathway development, consultation and education, research, and collaboration, with the specific knowledge and skills of the pediatric nurse practitioner to function effectively with sick children in the acute care areas.

Genetics of the complement system

After a brief history of complement genetics, general considerations and applications to our understanding of immune function, evolution, population structure and migration and forensic medicine, selected topics in complement genetics are presented. For individual complement proteins, genetic polymorphisms and deficiency states are described, as are the molecular bases of some of them. The clinical abnormalities exhibited by some patients with complement deficiency states are discussed, as are possible pathophysiologic mechanisms for them. The chromosomal location and the close linkage and a sharing of structural features by groups of complement proteins, such as the complotypes of the major histocompatibility complex, the regulators of complement activation, Clr and Cls, and the terminal components C6, C7 and C9, are presented in some detail. From these facts, the broad outlines are drawn of the evolution of the classical and alternative complement pathways from the lectin pathway and the terminal pathway from a common progenitor. From markers within the complotype region, rough conclusions are delineated regarding the evolution of C2, factor B, C4A and C4B alleles.

Plasmodesmata: gatekeepers for cell-to-cell transport of developmental signals in plants

Cell walls separate individual plant cells. To enable essential intercellular communication, plants have evolved membrane-lined channels, termed plasmodesmata, that interconnect the cytoplasm between neighboring cells. Historically, plasmodesmata were viewed as facilitating traffic of low-molecular weight growth regulators and nutrients critical to growth. Evidence for macromolecular transport via plasmodesmata was solely based on the exploitation of plasmodesmata by plant viruses during infectious spread. Now plasmodesmata are revealed to transport endogenous proteins, including transcription factors important for development. Two general types of proteins, non-targeted and plasmodesmata-targeted, traffic plasmodesmata channels. Size and subcellular location influence non-targeted protein transportability. Superimposed on cargo-specific parameters, plasmodesmata themselves fluctuate in aperture between closed, open, and dilated. Furthermore, plasmodesmata alter their transport capacity temporally during development and spatially in different regions of the plant. Plasmodesmata are exposed as major gatekeepers of signaling molecules that facilitate or regulate developmental programs, maintain physiological status, and respond to pathogens.

A cluster of genes for the biosynthesis of spinosyns, novel macrolide insect control agents produced by Saccharopolyspora spinosa

Spinosyns A and D are the active ingredients in a family of insect control agents produced by fermentation of Saccharopolyspora spinosa. Spinosyns are 21-carbon tetracyclic lactones to which are attached two deoxysugars. Most of the genes involved in spinosyn biosynthesis are clustered in an 74 kb region of the S. spinosa genome. This region has been characterized by DNA sequence analysis and by targeted gene disruptions. The spinosyn biosynthetic gene cluster contains five large genes encoding a type I polyketide synthase, and 14 genes involved in modification of the macrolactone, or in the synthesis, modification and attachment of the deoxysugars. Four genes required for rhamnose biosynthesis (two of which are also required for forosamine biosynthesis) are not present in the cluster. A pathway for the biosynthesis of spinosyns is proposed.

Polymer-supported tetrafluorophenol: a new activated resin for chemical library synthesis

A new tetrafluorophenol activated resin that facilitates the use of 19F NMR to quantitate loading is presented. This new resin provides a useful tool for acylation, and a novel activated polymeric sulfonate ester to generate sulfonamides. This activated resin reacts with a wide scope of N-nucleophiles including primary and secondary amines, and anilines. This new activated resin methodology provides a powerful tool for pure single-compound library synthesis.

Conceptually new 20-epi-22-oxa sulfone analogues of the hormone 1alpha,25-dihydroxyvitamin D(3): synthesis and biological evaluation

New C,D-ring side-chain-modified sulfone 4a, with natural 1alpha, 3beta-hydroxyl groups but lacking the 25-hydroxyl group characteristic of the natural hormone 1alpha,25-dihydroxyvitamin D(3) (1), has been prepared and characterized. Novel synthetic features include: (1) chemoselective oxidation of only a primary silyl ether in a primary-secondary bis-silyl ether intermediate and (2) smooth reductive etherification without interference by a neighboring sulfonyl group. Sulfone 4a, but not its 1beta, 3alpha-diastereomer 4b, is powerfully antiproliferative and transcriptionally active in vitro but desirably noncalcemic in vivo. Although sulfone 4a, designed to resemble Leo Pharmaceutical Co.'s KH-1060 (3), is recognized by catabolic enzymes, the selective biological profile of sulfone 4a is likely not due to its metabolites that are formed in only minor amounts.

Reversible cognitive decline accompanies migraine and cluster headaches

Vascular headaches, including migraine, cluster, and migrainous transformation to chronic daily headaches, are disabling. During and shortly after headache intervals, difficulties are reported in concentration, comprehension, and communication, not accounted for by nausea, photophobia, or sonophobia. These interfere with interpersonal relations and performance at work with economic loss. The hypothesis tested and reported here is that cognitive impairments comprise an important part of vascular headache diatheses. One hundred ninety-six otherwise normative subjects suffering from migraine or cluster, but not tension-type, headaches (136 women, 63 men; mean age, 46 years) participated in an outpatient prospective trial. One hundred thirty-three patients had migraine without aura, 39 migraine with aura, 11 periodic cluster (by IHS criteria), and 13 had migrainous transformation into chronic daily headaches. Neuropsychological testing was compared with and without headaches, by combined Mini-Mental Status Examination (MMSE), Cognitive Capacity Screening Examination (CCSE), and Hamilton Depression Rating Scale (HDRS). During headache intervals, significant decline was measured in both CCSE and MMSE scores (P <. 001) without HDRS change in all types of vascular headache and independent of headache severity, which often improved, or associated physical symptoms. Cognitive decline was promptly relieved by serotonin agonists and sleep. Disorders of cerebral serotoninergic projection systems appear to cause these reversible cognitive impairments.

Evaluation of hepatitis C virus glycoprotein E2 for vaccine design: an endoplasmic reticulum-retained recombinant protein is superior to secreted recombinant protein and DNA-based vaccine candidates

Hepatitis C virus (HCV) is the leading causative agent of blood-borne chronic hepatitis and is the target of intensive vaccine research. The virus genome encodes a number of structural and nonstructural antigens which could be used in a subunit vaccine. The HCV envelope glycoprotein E2 has recently been shown to bind CD81 on human cells and therefore is a prime candidate for inclusion in any such vaccine. The experiments presented here assessed the optimal form of HCV E2 antigen from the perspective of antibody generation. The quality of recombinant E2 protein was evaluated by both the capacity to bind its putative receptor CD81 on human cells and the ability to elicit antibodies that inhibited this binding (NOB antibodies). We show that truncated E2 proteins expressed in mammalian cells bind with high efficiency to human cells and elicit NOB antibodies in guinea pigs only when purified from the core-glycosylated intracellular fraction, whereas the complex-glycosylated secreted fraction does not bind and elicits no NOB antibodies. We also show that carbohydrate moieties are not necessary for E2 binding to human cells and that only the monomeric nonaggregated fraction can bind to CD81. Moreover, comparing recombinant intracellular E2 protein to several E2-encoding DNA vaccines in mice, we found that protein immunization is superior to DNA in both the quantity and quality of the antibody response elicited. Together, our data suggest that to elicit antibodies aimed at blocking HCV binding to CD81 on human cells, the antigen of choice is a mammalian cell-expressed, monomeric E2 protein purified from the intracellular fraction.

Cardiovascular and other risk factors for Alzheimer's disease and vascular dementia

Factors accelerating cerebral degenerative changes represent potentially modifiable risks for cognitive decline. Putative risks accelerating subtle cognitive decline and dementia were correlated with repeated measures of cerebral atrophy, CT densitometry, perfusions, and cognitive testing among 224 neurologically and cognitively normative aging volunteers. After age 60, cerebral atrophy, ventricular enlargement, polioaraiosis, and leukoaraiosis geometrically increased as perfusions declined. Risks accelerating perfusional decline, cerebral atrophy, polioaraiosis, and leukoaraiosis were: transient ischemic attacks (TIAs), hypertension, smoking, hyperlipidemia, male gender. At age 71.5 +/- 11.9, subtle cognitive decline began, accelerated by TIAs, hypertension, and heart disease. Leukoaraiosis began before cognitive decline. TIAs, hypertension, and hyperlipidemia correlated with vascular dementias. Excessive cortical perfusional decreases and cerebral atrophy correlated with cognitive decline. Family history of neurodegenerative disease correlated with Alzheimer's disease. We concluded that TIAs, hypertension, hyperlipidemia, smoking, and male gender accelerate cerebral degenerative changes, cognitive decline, and dementia.

Risk factors accelerating cerebral degenerative changes, cognitive decline and dementia

OBJECTIVES

Factors accelerating cerebral degenerative changes represent potentially modifiable risks for cognitive decline. Putative risk factors accelerating subtle cognitive decline and dementia were correlated with repeated measures of cerebral atrophy, CT densitometry, perfusions and cognitive testing among neurologically and cognitively normative ageing volunteers.

METHODS

Two hundred and twenty-four normative subjects at increased risk for cognitive decline were admitted to the study. Mean entry age was 59. 5+/-15.8 years. Mean follow-up is 4.3+/-3.1 years. At follow-up, 22 developed subtle cognitive decline (deltaCCSE>/=-3), 19 became demented, eight with vascular type (VAD) and 11 with Alzheimer's type (DAT) and 183 remain cognitively unchanged. Standardized questionnaires, medical, neuropsychological, neurological and blood work examinations were obtained. Cerebral atrophy, tissue densities and perfusions were measured by xenon-enhanced CT.

RESULTS

After age 60, cerebral atrophy, ventricular enlargement, polio- and leuko-araiosis geometrically increased as perfusions declined. Risk factors accelerating perfusional decline, cerebral atrophy, polio-araiosis and leuko-araiosis (thinning of grey-white matter densities) were: transient ischaemic attacks (TIAs), hypertension, smoking, hyperlipidemia, male gender. At age 71.5+/-11.9, subtle cognitive decline began, accelerated by TIAs, hypertension and heart disease. Leuko-araiosis began before cognitive decline. TIAs, hypertension and hyperlipidemia correlated with VAD. Excessive cortical perfusional decreases and cerebral atrophy correlated with cognitive decline. Family history of neurodegenerative disease correlated with DAT.

CONCLUSION

TIAs, hypertension, hyperlipidemia, smoking and male gender accelerate cerebral degenerative changes, cognitive decline and dementia.

XE-CT CBF changes during normative aging, cognitive decline and dementia

Factors accelerating cerebral degenerative changes represent potentially modifiable risks for cognitive decline. Putative risk factors accelerating mild cognitive decline and dementia were correlated with repeated measures of cerebral atrophy, CT densitometry, perfusions and cognitive testing among neurologically and cognitively normative volunteers. TIAs, hypertension, smoking and male gender accelerate cerebral degenerative changes, mild cognitive decline and dementia. Intervention by control of risk factors and cholinesterase inhibitors should prevent cerebral atropho-degenerative changes so that optimal cognitive performance is maintained.

Circulating CD2+ monocytes are dendritic cells

Low levels of CD2 have been described on subsets of monocytes, macrophages, and dendritic cells. CD2 is expressed on about one-third of circulating monocytes, at levels one-half log lower than on T or NK cells, representing 2-4% of PBMC. FACS analysis of CD2+ and CD2- monocytes revealed no significant difference in the expression of adhesion molecules (CD11a/b/c), class II Ags (HLA-DR, -DQ, -DP), myeloid Ags (CD13, CD14, CD33), or costimulatory molecules (CD80, CD86). Freshly isolated CD2+ and CD2- monocytes were morphologically indistinguishable by phase contrast microscopy. However, scanning electron microscopy revealed large prominent ruffles on CD2+ monocytes in contrast to small knob-like projections on CD2- monocytes. After 2 days of culture, the CD2+ monocytes largely lost CD14 expression and developed distinct dendrites, whereas the CD2- monocytes retained surface CD14 and remained round or oval. Freshly isolated CD2+ monocytes were more potent inducers of the allogeneic MLR and more efficiently induced proliferation of naive T cells in the presence of HIV-1 gp120 than did CD2- monocytes. After culture in the presence of GM/CSF and IL-4, CD2+ monocytes were up to 40-fold more potent than monocyte-derived dendritic cells or CD2- monocytes at inducing allogeneic T cell proliferation. These findings suggest that circulating CD2+ and CD2- monocytes are dendritic cells and the precursors of macrophages, respectively. Thus, dendritic cells are far more abundant in the blood than previously thought, and they and precursors of macrophages exist in the circulation as phenotypically, morphologically, and functionally distinct monocyte populations.

Risk factors accelerating cerebral degenerative changes, cognitive decline and dementia

OBJECTIVES

Factors accelerating cerebral degenerative changes represent potentially modifiable risks for cognitive decline. Putative risk factors accelerating subtle cognitive decline and dementia were correlated with repeated measures of cerebral atrophy, CT densitometry, perfusions and cognitive testing among neurologically and cognitively normative ageing volunteers.

METHODS

Two hundred and twenty-four normative subjects at increased risk for cognitive decline were admitted to the study. Mean entry age was 59. 5+/-15.8 years. Mean follow-up is 4.3+/-3.1 years. At follow-up, 22 developed subtle cognitive decline (deltaCCSE>/=-3), 19 became demented, eight with vascular type (VAD) and 11 with Alzheimer's type (DAT) and 183 remain cognitively unchanged. Standardized questionnaires, medical, neuropsychological, neurological and blood work examinations were obtained. Cerebral atrophy, tissue densities and perfusions were measured by xenon-enhanced CT.

RESULTS

After age 60, cerebral atrophy, ventricular enlargement, polio- and leuko-araiosis geometrically increased as perfusions declined. Risk factors accelerating perfusional decline, cerebral atrophy, polio-araiosis and leuko-araiosis (thinning of grey-white matter densities) were: transient ischaemic attacks (TIAs), hypertension, smoking, hyperlipidemia, male gender. At age 71.5+/-11.9, subtle cognitive decline began, accelerated by TIAs, hypertension and heart disease. Leuko-araiosis began before cognitive decline. TIAs, hypertension and hyperlipidemia correlated with VAD. Excessive cortical perfusional decreases and cerebral atrophy correlated with cognitive decline. Family history of neurodegenerative disease correlated with DAT.

CONCLUSION

TIAs, hypertension, hyperlipidemia, smoking and male gender accelerate cerebral degenerative changes, cognitive decline and dementia.

Conceptually new sulfone analogues of the hormone 1alpha, 25-dihydroxyvitamin D(3): synthesis and preliminary biological evaluation

A conceptually new series of vitamin D(3)-like nonfluorinated and fluorinated 16-ene side chain tert-butyl sulfones 3-7 has been synthesized. Even though these novel C,D-ring side chain analogues of the hormone 1alpha,25-dihydroxyvitamin D(3) (1,1,25D(3)) lack a terminal OH group, thought previously to be essential for high biological activity, they are highly antiproliferative and, in several cases, transcriptionally active in vitro but desirably noncalcemic in vivo. The side chain sulfone group may be binding to the nVDR as a hydrogen-bond acceptor, in contrast to the hydrogen-bond donor function of the 25-OH group of natural 1,25D(3).

Retinoic acid and thyroid hormone may function through similar and competitive pathways in regenerating axolotls

The objective of this study was to determine whether thyroid hormone (TH) would interfere with retinoic acid (RA), which proximalizes axolotl larvae regenerate limb pattern. RA and TH are ligands for members of the steroid hormone thyroid hormone nuclear binding protein superfamily which form functional homodimers, but may also form stable heterodimers with the RXR protein and may recognize identical DNA sequences. TH alone does not affect limb pattern but induces metamorphosis in regenerating animals. Coinjected animals do not metamorphose, and when compared to RA controls regenerate more proximal and in some cases anteroposterior (AP) and dorsoventral (DV) duplicate limb structures. In addition, the tissues that are normally lost or changed during metamorphosis appear to be sensitized resulting in the formation of (1) new dorsal gill lamellae accompanied by bifurcation and broadening of the original gill lamellae, (2) partial resorption of the tail fin, and (3) changes in eye position and snout morphology. Bifurcation of gill lamellae tips, but not the formation of supernumerary gills, is also observed in animals treated with RA alone. These results indicate that the molecular mechanism of RA and TH function through similar and perhaps competitive pathways.

In vitro strength comparison of hydroxyapatite cement and polymethylmethacrylate in subchondral defects in caprine femora

Hydroxyapatite cement was investigated in situ for the reconstruction of juxta-articular defects. Polymethylmethacrylate is currently the most commonly used material for the reconstruction of bone defects following the exteriorization and curettage of aggressive benign tumors. In vitro, we compared the effects of hydroxyapatite cement and polymethylmethacrylate in restoring the stiffness of the subchondral plate in a caprine femoral defect model. Ten matched pairs of caprine femora underwent nondestructive compression testing normal to the load-bearing surface. A standardized subchondral defect 12 mm in diameter was created in the medial femoral condyle. Compression testing was repeated to determine the reduction in stiffness caused by the defect. Each femur from each pair was randomly assigned to one of two groups (n=9), and the defects were augmented with either polymethylmethacrylate or hydroxyapatite cement. After 12 hours, compression testing was repeated to determine the subchondral stiffness after augmentation. Compared with intact femora, the defect specimens that were later treated with either polymethylmethacrylate or hydroxyapatite cement exhibited stiffness values of 70 (386+/-107 N/mm) and 59% (343+/-94 N/mm) respectively, which represented a significant reduction in stiffness (p=0.05). Augmentation with polymethylmethacrylate or hydroxyapatite cement restored stiffness by 81 (450+/-111 N/mm) and 71% (413+/-115 N/mm), respectively, of the values of intact specimens. Hydroxyapatite cement restored stiffness significantly (p=0.05) over the stiffness of the nonaugmented defect compared with the stiffness after augmentation with polymethylmethacrylate (p=0.12). Neither polymethylmethacrylate nor hydroxyapatite cement restored stiffness to that of intact femora (p=0.05). In the current detect model, hydroxyapatite cement was comparable with polymethylmethacrylate in restoring subchondral stiffness. Unlike polymethylmethacrylate, however, hydroxyapatite cement has the following advantages: it is osteoconductive, is replaced by host bone, and avoids the potential for thermal necrosis. Hydroxyapatite cement may therefore provide a viable alternative to polymethylmethacrylate for augmentation of juxta-articular and other bone defects.

Racial/ethnic disparities in admissions to public and private psychiatric inpatient settings: the effect of managed care

This study investigates the effect of managed care on access patterns among people of color who are severely and persistently mentally ill. The distribution of admissions to public and private psychiatric hospitals was compared for African-American, Asian, Latino, and white case managed clients of the Massachusetts Department of Mental Health before and after implementation of Medicaid managed mental health care in October 1997. Managed care appears to have increased access to private services across all racial and ethnic groups, although admissions of non-white patients were still more likely to take place in publicly operated settings. These data suggest that equalizing access to putatively better inpatient treatment settings may be an externality of managed care.

Rescue of cardiac alpha-actin-deficient mice by enteric smooth muscle gamma-actin

The muscle actins in higher vertebrates display highly conserved amino acid sequences, yet they show distinct expression patterns. Thus, cardiac alpha-actin, skeletal alpha-actin, vascular smooth muscle alpha-actin, and enteric smooth muscle gamma-actin comprise the major actins in their respective tissues. To assess the functional and developmental significance of cardiac alpha-actin, the murine (129/SvJ) cardiac alpha-actin gene was disrupted by homologous recombination. The majority ( approximately 56%) of the mice lacking cardiac alpha-actin do not survive to term, and the remainder generally die within 2 weeks of birth. Increased expression of vascular smooth muscle and skeletal alpha-actins is observed in the hearts of newborn homozygous mutants and also heterozygotes but apparently is insufficient to maintain myofibrillar integrity in the homozygous mutants. Mice lacking cardiac alpha-actin can be rescued to adulthood by the ectopic expression of enteric smooth muscle gamma-actin using the cardiac alpha-myosin heavy chain promoter. However, the hearts of such rescued cardiac alpha-actin-deficient mice are extremely hypodynamic, considerably enlarged, and hypertrophied. Furthermore, the transgenically expressed enteric smooth muscle gamma-actin reduces cardiac contractility in wild-type and heterozygous mice. These results demonstrate that alterations in actin composition in the fetal and adult heart are associated with severe structural and functional perturbations.

Effects of restricting levothyroxine dosage strength availability

We conducted a prospective, randomized, controlled trial to assess whether hospital formulary restrictions involving limiting dosage strengths of levothyroxine affect physicians' ability to manage patients effectively and provide pharmacy cost savings in a tertiary care federal government research hospital. Thirty-three endocrinologists were randomly assigned to prescribe levothyroxine from a restrictive (dosage strengths of 25, 50, 100, 125, and 150 micrograms) or a nonrestrictive (dosage strengths of 25, 50, 75, 100, 112, 125, 150, 175, 200, and 300 micrograms) formulary through a central computer system. Their 241 respective outpatients' laboratory results and drug compliance were outcome measures. Achievement of treatment objectives was measured by thyroid function tests (free and total thyroxine, total triiodothyronine, thyrotropin), number of clinic visits, and compliance (survey method). Additional measures were drug distribution patterns, drug costs, and pharmacy inventory costs. Restriction of levothyroxine's dosage strength did not significantly alter therapeutic outcomes. However, the restricted formulary was associated with more complex dosing regimens, and resulted in no significant cost savings. It is not known whether such restriction would adversely affect the care of patients of nonspecialists. Prospective studies are required to verify presumed cost-containment measures before such measures are adopted for widespread application.

Reproducibility in the measurement of atlanto-occipital instability in children with Down syndrome

STUDY DESIGN

This study compared the reproducibility of three techniques used to measure translation between the occiput and C1 in children with Down syndrome.

OBJECTIVES

Intraobserver and interobserver variability were computed to determine if there is a reliable way to measure occiput-C1 instability.

SUMMARY OF BACKGROUND DATA

No studies have been performed comparing measurement techniques in children with Dow syndrome.

METHODS

Powers ratios, basion-axial intervals, and translational anteroposterior motion as described by Wiesel and Rothman were calculated for 50 pairs of flexion-extension lateral cervical radiographs from children with Down syndrome. Calculations were made on two occasions by four reviewers.

RESULTS

Mean differences between measurements for two observers were 0.14 for the Powers ratio, 1.3 mm for the Wiesel technique, and 1.8 mm for the basion-axial interval. The 95th percentiles of the differences between measurements for two observers were 0.38 for Powers ratios, 3.5 mm for the Wiesel technique, and 5.3 mm for the basion-axial interval.

CONCLUSIONS

Measurement of atlanto-occipital translation by any of these methods is not reproducible. Although the technique by Wiesel and Rothman is the easiest to apply, confirmation of instability with magnetic resonance imaging should guide management.

Severe lumbar lordosis after dorsal rhizotomy

Two children with spastic quadriplegia who developed excessive lumbar lordosis after selective dorsal rhizotomy are described. The rhizotomy did not change the ambulatory status of either child (one nonambulator, one household ambulator). Preservation of unopposed hip flexion in the presence of multiple laminectomies may lead to the development of a lordotic deformity in children who sit most of the time. Excessive lumbar lordosis may cause pain and difficulty in sitting. Surgical correction of this deformity is complex because of the removal of posterior elements during the rhizotomy.

Evaluation of fluid absorption during laser prostatectomy by breath ethanol techniques

PURPOSE

Laser prostatectomy has evolved as a less invasive method of relieving bladder outlet obstruction due to prostatic enlargement. The elimination of adenomatous tissue by laser induced coagulation necrosis theoretically avoids the sequelae of fluid absorption noted during traditional transurethral resection of the prostate. However, to our knowledge no accurate determination of fluid absorption during laser prostatectomy has been performed to date.

MATERIALS AND METHODS

A technique previously described to determine the amount of irrigant absorbed during transurethral resection of the prostate measures breath ethanol levels using a standard alcohol breath analyzer during the procedure after a predetermined amount of ethanol is added to the irrigant fluid. This method was used in 4 men undergoing laser prostatectomy.

RESULTS

All 4 subjects had ethanol levels of 0 throughout the operation, indicating that little or no irrigant fluid was absorbed.

CONCLUSIONS

We demonstrated in a quantitative manner that fluid absorption during laser prostatectomy is almost nil and patients are, indeed, at no risk for the transurethral resection syndrome.

Tissue-nonspecific alkaline phosphatase participates in the establishment and growth of feather germs in embryonic chick skin cultures

Alkaline phosphatase activity is present in the mesoderm of embryonic chick skin and becomes spatially restricted to the dermal condensation of the developing feather germs. Inhibitors to tissue-nonspecific (liver/bone/kidney), but not intestinal alkaline phosphatase inhibit the establishment and growth of feather germs in cultured skins. A window of maximum sensitivity to the inhibitor was observed to be the first day of culture when early development and establishment of pattern takes place. The cDNA for the avian tissue-nonspecific alkaline phosphatase was cloned and sequenced, and Southern analysis revealed a single copy of this gene in the avian genome. Northern analysis revealed that a 2.8 kb transcript for this form of alkaline phosphatase is present in developing skin.

Dominant mutants identify new roles for p34cdc2 in mitosis

A large number of dominant mutants have been generated in the fission yeast cdc2 gene, causing lethality when expressed in wild-type cells. The mutants interfere with distinct aspects of p34cdc2 function, producing one of four different phenotypes: mitotic arrest, multiple rounds of S phase in the absence of mitosis, premature mitosis or G2 arrest. The mitotic mutants DL41, DL45 and DL50 are characterized in this paper. Over-expression of DL41 or DL45 causes mitotic arrest, specifically interfering with sister chromatid separation, without preventing spindle elongation. This suggests a role for p34cdc2 in triggering sister chromatid separation at anaphase. DL41 and DL45 also cause abnormal septum formation, suggesting that p34cdc2 may also be involved in regulating this process in fission yeast. These mitotic aspects of p34cdc2 function may involve interaction with p13suc1, since increased expression of suc1 partially suppresses DL41 and DL45. Over-expression of DL50 causes premature mitotic entry in cells that have not completed S phase, resulting in lethality. DL41, DL45 and DL50 correspond to mutation of p34cdc2 residues predicted to be on the surface of the protein, identifying potential sites of interaction with mitotic regulators of p3cdc2, and these residues are conserved amongst cdc2 proteins found in other eukaryotes.

Persistent hepatitis C virus infection in a chimpanzee is associated with emergence of a cytotoxic T lymphocyte escape variant

Hepatitis C virus (HCV) establishes a persistent infection in humans and chimpanzees despite the presence of virus-specific, class I major histocompatibility complex-restricted CD8+ cytotoxic T lymphocytes (CTLs) in the liver. The data presented here demonstrate that CTLs directed against a conserved epitope in the HCV nonstructural 3 protein persist in the liver of a chronically infected chimpanzee for at least 2 years after infection. However, these CTLs did not recognize the HCV quasi-species present in the plasma of this animal at week 16 postinfection or at later time points. Escape from the CTL response was facilitated by an aspartic acid to glutamic acid (D-->E) substitution at amino acid position 1449 in all HCV genomes that were sequenced. The results of this study strongly support the concept that CTL responses can select for variant viruses with an enhanced ability to persist in a host and have important implications for the design of vaccines against HCV.

Terfenadine metabolism in human liver. In vitro inhibition by macrolide antibiotics and azole antifungals

To determine whether the clinical adverse interactions of terfenadine with azole antifungals and macrolide antibiotics may be related to inhibition of terfenadine biotransformation, an in vitro system was developed to follow the metabolism of terfenadine by rat liver S9 or human liver microsomes. When test compounds were coincubated with terfenadine, the metabolites formed and unchanged terfenadine was quantitatively analyzed by HPLC. Five metabolites of terfenadine were formed by rat liver S9: predominantly alcohol metabolite (III), with four minor metabolites--azacyclonol (I), acid metabolite (II), an unidentified metabolite (IV), and a new ketone metabolite (V). By human liver microsomes, two major metabolites were formed: azacyclonol (I) and alcohol metabolite (III). Ketoconazole, fluconazole, itraconazole, erythromycin, clarithromycin, and troleandomycin potently inhibited terfenadine metabolism by human liver (IC50 = 4-10 microM), but inhibition by rat liver was weaker (IC50 = 87-218 microM) and 18% maximally for troleandomycin. Other CYP3A substrates (cyclosporin A, naringenin, and midazolam) also demonstrated potent inhibition of terfenadine biotransformation in human liver microsomes (IC50 = 17-24 microM). Substrates of other P450 families [sparteine (CYP2D6), caffeine (CYP1A), and diclofenac (CYP2C)] only very weakly inhibited terfenadine metabolism. Dixon plot analyses for human liver revealed competitive/reversible inhibition by the azole antifungals and macrolide antibiotics of azacyclonol and alcohol metabolite formations.(ABSTRACT TRUNCATED AT 250 WORDS)

Essential role of vif in establishing productive HIV-1 infection in peripheral blood T lymphocytes and monocyte/macrophages

The role of vif during the establishment of human immunodeficiency virus type 1 (HIV-1) infection of peripheral blood T lymphocytes and monocyte/macrophages was investigated using vif mutants of three HIV-1 proviral DNAs. Vif was found to be essential for the establishment of productive HIV-1 infection in peripheral blood T lymphocytes after cell-free infection with HXB2 and DFCI-HD, a vpr-positive, vpu-positive, nef-positive derivative of HXB2. A chimeric HIV-1 provirus in which the T-cell line-tropic env sequences in DFCI-HD were replaced with the macrophagetropic env of the ADA strain was constructed for studies on the role of vif during the establishment of HIV-1 infection in primary monocyte/macrophages. These studies showed that vif is also essential for the initiation of productive HIV-1 infection in primary monocyte/macrophage cultures after cell-free virus transmission. The DFCI-HD-ADA virus was shown to replicate in the CD4+ T-cell line Molt 4 clone 8 but not in other T-cell or monocytic cell lines, as previously shown for another macrophagetropic strain YU-2 (1), suggesting that this cell line may be useful for future studies on at least some macrophagetropic strains of HIV-1. The finding that vif is essential for the establishment of productive HIV-1 infection in primary T lymphocytes and monocyte/macrophages suggests that vif may be required for HIV-1 transmission and disease pathogenesis during natural infections and thus may be a good target for prophylactic or therapeutic intervention.

A unique, predominant hepatitis C virus variant found in an infant born to a mother with multiple variants

To demonstrate vertical transmission of hepatitis C virus (HCV) from an HCV-infected, non-human immunodeficiency virus type 1-infected mother to her infant and to assess the distribution of viral species in the mother and infant, the hypervariable region of the gene encoding the putative envelope glycoprotein E2 (E2HV) was sequenced in three mothers and one mother-infant pair. The data indicate that (i) quasi-species distributions of HCV E2HV variants were found in all four mothers, (ii) a single predominant HCV E2HV variant was found in the infant of a mother shown to have nine predominant E2HV variants, and (iii) the infant's E2HV variant was highly related to, but not identical with, the nine variants identified in the mother at the time of birth. These findings indicate that HCV is transmitted from mother to infant and raise the possibility that the transmission occurs in utero.

The hepatitis C virus encodes a serine protease involved in processing of the putative nonstructural proteins from the viral polyprotein precursor

The hepatitis C virus (HCV) nonstructural protein 3 (NS3) domain has been predicted from sequence comparisons to represent a trypsin-like serine protease. By expressing wild-type and mutant HCV-1 cDNAs in transfected mammalian cells, we have identified putative nonstructural proteins 3 (72 kDa), 4 (10 kDa and 27 kDa) and 5 (58 kDa) and have shown that their processing from the viral polyprotein precursor is dependent on Ser1165 located in the proposed protease catalytic site. Data obtained from in vitro RNA translations indicate that unlike the processing of the NS2/NS3 junction, NS3/NS4 processing is dependent on Ser1165. In contrast to the situation for the related flaviviral NS3 proteases, the HCV NS3-mediated cleavage of the NS3/NS4 junction does not require the upstream NS2 domain and may not occur at dibasic sites.

Dietary restriction of adult male rhesus monkeys: design, methodology, and preliminary findings from the first year of study

Dietary restriction (DR) retards aging processes and extends maximum life span in rodents and in simpler animals. We initiated a study in 30 adults (8-14 years old) male rhesus monkeys to determine whether or not aging processes are retarded by adult-onset DR in a primate species and herein report results from the experiment's first year. Following a 3-6 month period when baseline data were obtained, 15 animals were assigned to a control group and given free access to a semipurified diet for 6-8 hours per day. The other 15 monkeys were fed the same diet but at 70% of their baseline intake levels predetermined individually. The animals are being evaluated semi-annually for body size and composition, physical activity, metabolic rate, glucose tolerance and insulin sensitivity, hematologic indices, immunologic function, and fingernail growth. Ocular function is assessed annually. The preliminary observations after one year are: (a) all monkeys appear to be in excellent health; (b) average body weights for controls increased by 9% while monkeys on DR did not gain weight; (c) monkeys on DR have less body fat than do control monkeys, whereas the amount of lean body mass has not been significantly influenced by DR; (d) there was a small but statistically significant reduction in physical activity for monkeys on DR relative to controls; and (e) DR has not overtly influenced the other measures. Control monkeys gradually reduced their voluntary levels of food intake during the first year of study, and food allotments to DR monkeys are being adjusted accordingly in order to reinstate the intended 30% difference between groups. These early data indicate that DR can be safely instituted in adult monkeys, but that longer term and/or more severe DR is required to determine if it is capable of influencing age-sensitive indices in long-lived primates.

Characterization of the hepatitis C virus E2/NS1 gene product expressed in mammalian cells

Truncated and full-length versions of the hepatitis C virus protein domain encoding a presumptive envelope glycoprotein designated E2/NS1 were stably expressed in CHO cell lines. Characterization of the processing events involved in the maturation of E2/NS1 revealed that a high-mannose form resident in the endoplasmic reticulum was the most abundant form detected intracellularly. The ionophore carboxyl cyanide m-chlorophenyl-hydrazone was used to show that the E2/NS1 glycoprotein resided in the endoplasmic reticulum. The full-length form of E2/NS1 appeared to be cell-associated and could not be detected as a secreted product. C-terminal truncated molecules could be detected in the extracellular media as fully processed glycoproteins containing terminal sialic acid additions. These truncated glycoproteins are predicted to be biologically relevant targets of the host immune response and are therefore potential subunit vaccine candidates.