Relative influence of heritability, environment and genetics on serum sclerostin.

SUMMARY: We determined factors associated with serum sclerostin in 446 Afro-Caribbean family members. Age, weight, sex, diabetes and kidney function were associated with sclerostin. Sclerostin was heritable, and nine SNPs in the SOST gene region were associated with sclerostin. Variation in serum sclerostin is a heritable factor that is determined by both genetic and environmental factors. INTRODUCTION: Sclerostin, encoded by the SOST gene, is a Wnt inhibitor that regulates bone mineralization and is a candidate gene locus for osteoporosis. However, little is known about the genetic and non-genetic sources of inter-individual variation in serum sclerostin levels. METHODS: Serum sclerostin was measured in 446 Afro-Caribbean men and women aged 18+ from seven large, multigenerational families (mean family size, 64; 3,840 relative pairs). Thirty-six common single nucleotide polymorphisms (SNP) were genotyped within a 100 kb region encompassing the gene encoding sclerostin (SOST). Genetic and non-genetic factors were tested for association with serum sclerostin. RESULTS: Mean serum sclerostin was 41.3 pmol/l and was greater in men than in women (P < 0.05). Factors associated with higher serum sclerostin were increased age and body weight, male sex, diabetes and decreased glomerular filtration rate, which collectively accounted for 25.4 % of its variation. Residual genetic heritability of serum sclerostin was 0.393 (P < 0.0001). Nine SNPs reached nominal significance with sclerostin. Three of those nine SNPs represented independent association signals (rs851056, rs41455049 and rs9909172), which accounted for 7.8 % of the phenotypic variation in sclerostin, although none of these SNPs surpassed a Bonferroni correction for multiple comparisons. CONCLUSIONS: Serum sclerostin is a heritable trait that is also determined by environmental factors including age, sex, adiposity, diabetes and kidney function. Three independent common SNPs within the SOST region may collectively account for a significant proportion of the variation in serum sclerostin.

Bilayer graphene grown on 4H-SiC (0001) step-free mesas.

We demonstrate the first successful growth of large-area (200 × 200 µm(2)) bilayer, Bernal stacked, epitaxial graphene (EG) on atomically flat, 4H-SiC (0001) step-free mesas (SFMs) . The use of SFMs for the growth of graphene resulted in the complete elimination of surface step-bunching typically found after EG growth on conventional nominally on-axis SiC (0001) substrates. As a result heights of EG surface features are reduced by at least a factor of 50 from the heights found on conventional substrates. Evaluation of the EG across the SFM using the Raman 2D mode indicates Bernal stacking with low and uniform compressive lattice strain of only 0.05%. The uniformity of this strain is significantly improved, which is about 13-fold decrease of strain found for EG grown on conventional nominally on-axis substrates. The magnitude of the strain approaches values for stress-free exfoliated graphene flakes. Hall transport measurements on large area bilayer samples taken as a function of temperature from 4.3 to 300 K revealed an n-type carrier mobility that increased from 1170 to 1730 cm(2) V(-1) s(-1), and a corresponding sheet carrier density that decreased from 5.0 × 10(12) cm(-2) to 3.26 × 10(12) cm(-2). The transport is believed to occur predominantly through the top EG layer with the bottom layer screening the top layer from the substrate. These results demonstrate that EG synthesized on large area, perfectly flat on-axis mesa surfaces can be used to produce Bernal-stacked bilayer EG having excellent uniformity and reduced strain and provides the perfect opportunity for significant advancement of epitaxial graphene electronics technology.

Genetic analysis of serum osteocalcin and bone mineral in multigenerational Afro-Caribbean families.

UNLABELLED: Osteocalcin is a major component of bone matrix. Concentrations of total, carboxylated, and uncarboxylated osteocalcin, are highly heritable and genetically correlated with bone mineral content (BMC) within African ancestry families. INTRODUCTION: Osteocalcin (OC) is a protein constituent of bone matrix and a marker of bone formation. We characterized the heritability of serum OC measures and identified genomic regions potentially involved in the regulation of OC via high-density genome-wide linkage analysis in African ancestry individuals. METHODS: African ancestry individuals (n = 459) were recruited, without regard to health status, from seven probands (mean family size = 66; 4,373 relative pairs). Residual heritability of serum OC measures was estimated and multipoint quantitative trait linkage analysis was performed using pedigree-based maximum likelihood methods. RESULTS: Residual heritabilities of total OC, uncarboxylated OC, carboxylated OC and percent uncarboxylated OC were 0.74 ± 0.10, 0.89 ± 0.08, 0.46 ± 0.10 and 0.41 ± 0.09, respectively. All OC measures were genetically correlated with whole body BMC. We obtained strong evidence of bivariate linkage for percent uncarboxylated OC and whole body BMC on chromosome 17 (logarithm of the odds [LOD] = 3.15, 99 cM). CONCLUSIONS: All forms of OC were highly heritable and genetically correlated with total body BMC in these African ancestry families. The identified linkage region contains several candidate genes for bone and energy metabolism including COL1A1 and TNFRSF11A. Further studies of this genomic region may reveal novel insight into the genetic regulation of OC and bone mineralization.

Body Composition Across the Adult Lifespan in African Caribbean Men: The Tobago Longitudinal Study of Aging.

Body composition and muscle strength change vary by age and ethnicity, and have a major impact on health and physical function. Little is known about the patterns of these changes in African-ancestry populations. Herein, we examined age-specific (5-year age groups) rates-of-change in lean and fat mass in 1918 African-ancestry men on the Caribbean island of Tobago (baseline age: 62.0±11.8 years, range: 40-99 years). Body composition (DXA) and grip strength were measured at three time points (baseline, 4- and 9-year follow-up). Annualized rates of change were calculated with all 3 time-points using Generalized Estimating Equations. We found that whole body lean mass declined at constant rate until age 65 (-0.72%/year; 95% CI: -0.76, -0.67), which accelerated to -0.92 %/year (-1.02, -0.82) among those 65-69, and again to -1.16 %/year (-1.30, -1.03 ) among those aged 70+. Whole body fat mass increased by a near constant rate of 2.93 %/year (2.72, 3.15%) across the lifespan. Finally, grip strength decline accelerated at age 50, and about 2x faster than lean mass through the lifespan after the age of 50. To conclude, in African-Caribbean men, the acceleration in muscle strength decline precedes the acceleration in lean mass decline by 10-15 years, suggesting decrements in factors other than lean mass drive this initial acceleration in muscle strength decline. We also found that African-Caribbean men undergo a constant shift to a more adipogenic phenotype throughout the adult lifespan (aged 40-99), which likely contributes to age-related loss of muscle and physical function.

Age-related decline in bone density among ethnically diverse older men.

UNLABELLED: We compared rates of BMD decline in older men of diverse ethnic background. The rate of bone loss was statistically equivalent between men of African and Caucasian descent. INTRODUCTION: Race differences in peak bone mineral density (BMD) are well established, but the magnitude of bone loss among non-white men has not been well characterized. Our objective was to compare and contrast the rates of decline in BMD with aging among older men of different race/ethnic groups. METHODS: The rate of decline in hip BMD was measured by dual-energy X-ray absorptiometry (Hologic QDR-4500 W) with an average follow-up of 4.6 years in 3,869 Caucasian, 138 African American, 145 Asian, and 334 Afro-Caribbean men aged ≥ 65 years (Mean ages: 73 ± 5, 70 ± 4, 72 ± 5, 71 ± 5 years, respectively). RESULTS: The annual rate of decline in BMD at the femoral neck was -0.32%, -0.42%, -0.09%, and -0.44%/year for Caucasian, African American, Asian, and Afro-Caribbean men, respectively (p < 0.05 for Caucasian versus Asian). Although men of African ancestry have higher peak BMD than Caucasians, rates of decline in BMD with aging appear to be statistically equivalent in our study. In contrast, Asian men experienced a slower rate of decline in BMD compared with Caucasians and African Americans. CONCLUSION: More studies are needed to better define the natural history of and factors associated with bone loss among non-white men.

Association analysis of 33 lipoprotein candidate genes in multi-generational families of African ancestry.

African ancestry individuals have a more favorable lipoprotein profile than Caucasians, although the mechanisms for these differences remain unclear. We measured fasting serum lipoproteins and genotyped 768 tagging or potentially functional single nucleotide polymorphisms (SNPs) across 33 candidate gene regions in 401 Afro-Caribbeans older than 18 years belonging to 7 multi-generational pedigrees (mean family size 51, range 21-113, 3,426 relative pairs). All lipoproteins were significantly heritable (P<0.05). Gender-specific analysis showed that heritability for triglycerides was much higher (P<0.01) in women than in men (women, 0.62+/-0.18, P<0.01; men, 0.13+/-0.17, P>0.10), but the heritability for LDL cholesterol (LDL-C) was higher (P<0.05) in men than in women (men, 0.79+/-0.21, P<0.01; women, 0.39+/-0.12, P<0.01). The top 14 SNPs that passed the false discovery rate threshold in the families were then tested for replication in an independent population-based sample of 1,750 Afro-Caribbean men aged 40+ years. Our results revealed significant associations for three SNPs in two genes (rs5929 and rs6511720 in LDLR and rs7517090 in PCSK9) and LDL-C in both the family study and in the replication study. Our findings suggest that LDLR and PCSK9 variants may contribute to a variation in LDL-C among African ancestry individuals. Future sequencing and functional studies of these loci may advance our understanding of genetic factors contributing to LDL-C in African ancestry populations.

Serum Vitamin D and Age-Related Muscle Loss in Afro-Caribbean Men: The Importance of Age and Diabetic Status.

BACKGROUND: Prospective studies examining the potential association of vitamin D with age-related muscle loss have shown inconsistent results. OBJECTIVE: To examine the association between baseline serum 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), and prospective change in lean mass with aging in African ancestry population. We also determined if associations were modulated by age and diabetes mellitus (DM). DESIGN: Prospective observational cohort study. SETTING: Data were collected from a random sub-sample of 574 men, participants of the Tobago Bone Health Study (TBHS). PARTICIPANTS: 574 Afro-Caribbean men, aged 43+ years (mean age: 59.1 ± 10.5), who were randomly selected as the participants in both the baseline and the follow-up visits. MEASUREMENTS: Baseline fasting serum 25(OH)D was measured using liquid chromatography mass spectrometry (LC-MS/MS), and and 1,25(OH)2D was measured using radioimmunosassay (RIA). Changes in dual-energy X-ray absorptiometry (DXA)-measured appendicular lean mass (ALM), and total body lean mass (TBLM) were measured over an average of 6.0 ± 0.5 years. The associations of 25(OH)D and 1,25(OH)2D with ALM and TBLM were assessed by multiple linear regression model after adjusting for potential confounders. RESULTS: When stratifying all men into two groups by age, greater baseline 25(OH)D and 1,25(OH)2D levels were associated with smaller losses of ALM and TBLM in older (age 60+ years) but not in younger (age 43 - 59 years) men. When stratifying by DM status, the associations of 25(OH)D and 1,25(OH)2D with declines in ALM and TBLM were statistically significant only in prediabetic, but not among normal glycemic or diabetic men. CONCLUSION: Higher endogenous vitamin D concentrations are associated with less lean mass loss with aging among older and prediabetic Afro-Caribbean men independent of potential confounders. Our findings raise a possibility that maintaining high serum vitamin D level might be important for musculoskeletal health in elderly and prediabetic African ancestry men.

Factors associated with HD CAG repeat instability in Huntington disease.

BACKGROUND: The Huntington disease (HD) CAG repeat exhibits dramatic instability when transmitted to subsequent generations. The instability of the HD disease allele in male intergenerational transmissions is reflected in the variability of the CAG repeat in DNA from the sperm of male carriers of the HD gene. RESULTS: In this study, we used a collection of 112 sperm DNAs from male HD gene-positive members of a large Venezuelan cohort to investigate the factors associated with repeat instability. We confirm previous observations that CAG repeat length is the strongest predictor of repeat-length variability in sperm, but we did not find any correlation between CAG repeat instability and either age at the time of sperm donation or affectedness status. We also investigated transmission instability for 184 father-offspring and 311 mother-offspring pairs in this Venezuelan pedigree. Repeat-length changes were dependent upon the sex of the transmitting parent and parental CAG repeat length but not parental age or birth order. Unexpectedly, in maternal transmissions, repeat-length changes were also dependent upon the sex of the offspring, with a tendency for expansion in male offspring and contraction in female offspring. CONCLUSION: Significant sibling-sibling correlation for repeat instability suggests that genetic factors play a role in intergenerational CAG repeat instability.

A comparative study of the prevalence of the metabolic syndrome and its components in type 2 diabetic patients in two Caribbean islands using the new International Diabetes Federation definition.

BACKGROUND AND AIM: Tobago and Trinidad are two Caribbean islands with distinct genetic background and lifestyles; while Tobago is serene and a tourist centre, Trinidad is characterized by a hustling and bustling lifestyle. The study was aimed at determining and comparing the prevalence of the metabolic syndrome (MetS) and its critical components in type 2 diabetic patients using the new International Diabetes Federation (IDF) definition. METHODS: Four hundred and thirteen (166 Tobago, 247 Trinidad) type 2 diabetic patients visiting 10 lifestyle disease clinics were studied. Blood pressure, anthropometric parameters (height, weight, body mass index and waist circumference) and overnight fasting blood samples were taken. Plasma glucose and serum triglycerides, total cholesterol, LDL- and HDL-cholesterol, insulin, and adiponectin were determined. Insulin resistance (IR) was determined using the HOMA method. RESULTS: The patients in Tobago were significantly older than patients in Trinidad (p < 0.001) but the duration of diabetes (9.4 +/- 0.5 vs. 11.1 +/- 0.7 yr), medications, generalized (31.7 vs. 38.8%) and central (78.5 vs. 83.7%) obesity were similar (p > 0.05). In comparison with patients in Tobago, diabetic patients in Trinidad, irrespective of gender, had significantly higher prevalence of IDF critical components such as raised BP, raised triglycerides and reduced HDL-cholesterol (all, p < 0.001). Thus, while more patients in Trinidad were diagnosed with MetS based on three or four components, more patients in Tobago were diagnosed based on two components (p < 0.001). CONCLUSIONS: There were high prevalence rates of the components of the MetS in both the islands of Tobago and Trinidad. Quantitatively, the aggregation of the components is higher in patients in Trinidad, which constitute greater risk for adverse cardiovascular outcome. Controlling central obesity should be the target in preventing MetS in the two islands.

Determining the nature of the gap in semiconducting graphene.

Since its discovery, graphene has held great promise as a two-dimensional (2D) metal with massless carriers and, thus, extremely high-mobility that is due to the character of the band structure that results in the so-called Dirac cone for the ideal, perfectly ordered crystal structure. This promise has led to only limited electronic device applications due to the lack of an energy gap which prevents the formation of conventional device geometries. Thus, several schemes for inducing a semiconductor band gap in graphene have been explored. These methods do result in samples whose resistivity increases with decreasing temperature, similar to the temperature dependence of a semiconductor. However, this temperature dependence can also be caused by highly diffusive transport that, in highly disordered materials, is caused by Anderson-Mott localization and which is not desirable for conventional device applications. In this letter, we demonstrate that in the diffusive case, the conventional description of the insulating state is inadequate and demonstrate a method for determining whether such transport behavior is due to a conventional semiconductor band gap.

Functionalized graphene as a model system for the two-dimensional metal-insulator transition.

Reports of metallic behavior in two-dimensional (2D) systems such as high mobility metal-oxide field effect transistors, insulating oxide interfaces, graphene, and MoS2 have challenged the well-known prediction of Abrahams, et al. that all 2D systems must be insulating. The existence of a metallic state for such a wide range of 2D systems thus reveals a wide gap in our understanding of 2D transport that has become more important as research in 2D systems expands. A key to understanding the 2D metallic state is the metal-insulator transition (MIT). In this report, we explore the nature of a disorder induced MIT in functionalized graphene, a model 2D system. Magneto-transport measurements show that weak-localization overwhelmingly drives the transition, in contradiction to theoretical assumptions that enhanced electron-electron interactions dominate. These results provide the first detailed picture of the nature of the transition from the metallic to insulating states of a 2D system.

Hot carrier relaxation of Dirac fermions in bilayer epitaxial graphene.

Energy relaxation of hot Dirac fermions in bilayer epitaxial graphene is experimentally investigated by magnetotransport measurements on Shubnikov-de Haas oscillations and weak localization. The hot-electron energy loss rate is found to follow the predicted Bloch-Grüneisen power-law behaviour of T(4) at carrier temperatures from 1.4 K up to ∼100 K, due to electron-acoustic phonon interactions with a deformation potential coupling constant of 22 eV. A carrier density dependence n(e)(-1.5) in the scaling of the T(4) power law is observed in bilayer graphene, in contrast to the n(e)(-0.5) dependence in monolayer graphene, leading to a crossover in the energy loss rate as a function of carrier density between these two systems. The electron-phonon relaxation time in bilayer graphene is also shown to be strongly carrier density dependent, while it remains constant for a wide range of carrier densities in monolayer graphene. Our results and comparisons between the bilayer and monolayer exhibit a more comprehensive picture of hot carrier dynamics in graphene systems.

Modification of the mouse mitochondrial genome by insertion of an exogenous gene.

Using homologous recombination in yeast we have inserted a synthetic gene encoding human ornithine transcarbamylase (sOTC), designed to allow mitochondrial (mt) translation, into the mouse mt genome. Modification of the mt genome was facilitated by its cloning into a yeast centromeric plasmid. The sOTC gene was initially flanked by 25 bp of the mt tRNA(His) gene at its 5' end and by 23 bp of the mt tRNA(Ser (AGY)) gene at its 3' end (Wheeler et al., 1996). In order to achieve homologous recombination the flanking homology was subsequently extended to 525 and 362 bp by the polymerase chain reaction (PCR). The sOTC gene was thus inserted into the cloned mt genome at a unique location between the tRNA(His) and tRNA(Ser (AGY)) genes. Positioning of the sOTC gene between these normally contiguous tRNA genes should allow its processing from the mt polycistronic transcript. The ability to modify the mammalian mt genome in this way is a valuable step towards a functional analysis of mt genetic mechanisms and possibly also towards a gene therapy approach for mt disorders.

Synthesis of a modified gene encoding human ornithine transcarbamylase for expression in mammalian mitochondrial and universal translation systems: a novel approach towards correction of a genetic defect.

The mitochondrial (MT) genome is a potential means of gene delivery to human cells for therapeutic expression. As a first step towards this, we have synthesized a gene coding for mature human ornithine transcarbamylase (OTC) by recursive PCR using 18 oligodeoxyribonucleotides, each 70-80 nucleotides in length, using codons which should allow translation in accordance with both mammalian mt and universal codon usage. Flanking mt DNA sequences were incorporated which are designed to facilitate site-specific cloning into the mt genome. Expression of this human gene in Escherichia coli leads to an immunoreactive OTC product of the correct size and N-terminal amino-acid sequence, but which forms inclusion bodies and lacks enzymatic activity.

Neocortical neurons cultured from mice with expanded CAG repeats in the huntingtin gene: unaltered vulnerability to excitotoxins and other insults.

Glutamate-mediated excitotoxicity might contribute to the pathogenesis of Huntington's disease and other polyglutamine repeat disorders. We used murine neocortical cultures derived from transgenic and knock-in mice to test the effect of expression of expanded polyglutamine-containing huntingtin on neuronal vulnerability to excitotoxins or other insults. Neurons cultured from mice expressing either a normal length (Hdh(Q20)) or expanded (Hdh(Q111)) CAG repeat as a knock-in genetic alteration in exon one of the mouse Hdh gene [Hum Mol Genet 8 (1999) 115] had similar vulnerability to N-methyl-D-aspartate (NMDA) and kainate-mediated excitotoxicity. These neurons also exhibited similar vulnerability to oxidative stress (24 h exposure to 10-100 microM paraquat or 1-10 microM menadione), apoptosis (48 h exposure to 30-100 nM staurosporine or 1 microM dizocilpine maleate (MK-801) and proteasome inhibition (48 h exposure to 0.3-3 microM MG-132). Neocortical neurons cultured from mice transgenic for an expanded CAG repeat-containing exon 1 of the human HD gene (Mangiarini et al., 1996, R6/2 line) and non-transgenic littermate controls also had similar vulnerability to NMDA and kainate-mediated excitotoxicity. These observations suggest that expression of expanded polyglutamine-containing huntingtin does not acutely alter the vulnerability of cortical neurons to excitotoxic, oxidative or apoptotic insults.

A resonance Raman spectroscopic study of the quadruplex form of polyriboinosinic acid.

The four stranded form of polyriboinosinic acid, or poly(rl), formed under conditions of high ionic strength, has been studied principally by resonance Raman spectroscopy excited in the ultraviolet absorbent band of the hypoxanthine residues. UV Absorption and circular dichroism studies were made, principally in order to verify the presence of the quadruplex form at the low concentrations of poly(rl) used, and a trial experiment with the structural probe Tb3+ was also performed. Experimental evidence is found for highly stacked metastable forms present at low concentrations of polynucleotide, which are destroyed by heating in favor of the two well known forms.

Folic acid and chromosome breakage. III. Types and frequencies of spontaneous chromosome aberrations in proliferating lymphocytes.

The types and frequencies of spontaneous chromosome aberrations were studied in human lymphocytes cultured for 96 h in minimal essential medium (MEM) or MEM without folic acid (MEM-FA). In both media, the most frequent aberrations were chromatid gaps, isochromatid gaps and chromatid breaks. Chromosome (isochromatid) breaks and dicentrics were seen less frequently. Neither of these less frequent aberrations was seen in 4000 cells from MEM, but both were seen in 4000 cells from MEM-FA.

Adhesives in larynx repair.

Guinea pig laryngeal fractures were used as a model to compare the ease of application and effectiveness of the fibrinogen-adhesive system with the ease of application and effectiveness of cyanoacrylate glue and control fractures stinted with contralateral gelatin film. Seven fibrin adhesive-treated and two cyanoacrylate glue-treated guinea pigs were perfused after 60 and 35 days, respectively. The larynges were serial sectioned, and the wound sites were compared. The fibrinogen adhesive system was easier to dispense than cyanoacrylate glue, did not require a completely dry surface, and stabilized within 3 minutes. Cartilage segment alignment with focal, complete fracture healing and symmetrical chondrocyte proliferation were seen in fibrogen adhesive-stinted larynges. In the cyanoacrylate glue-treated larynges, there was no alignment and minimal, asymmetrical chondrocyte proliferation. Gelatin film-stinted controls exhibited similar features. Thus, fibrogen adhesive was easier to apply and more effectively bound laryngeal fractures than cyanoacrylate glue or gelatin film.

HIV infection in the Caribbean.

The Caribbean is a multi-ethnic region with many different cultural differences. The majority of the population is of African descent, but there are also other ethnic groups present such as Indians, Chinese, Syrians and Europeans. The Caribbean region is influenced by countries such as the USA, Great Britain, France and Holland. The countries of the Caribbean have a serious problem with HIV infection and AIDS. The epidemiology of HIV infection in this region, is different from most other parts of the world in that the mode of spread does not easily fit into any of the three WHO patterns. This review shows that the infection initially started in the homosexual/bisexual community, but since then, it has moved to the heterosexual population and this form of contact is now the main mode of transmission of the virus. The Governments of the Caribbean countries have realized the extent of the problem and have taken measures to try to control the epidemic.

PIP: The Caribbean is a multi-ethnic region of great cultural diversity presently experiencing a serious problem with HIV infection and AIDS. Some of the countries have among the highest annual incidence rates of HIV infection and AIDS in the world. The number of AIDS cases reported keeps rising each year in most Caribbean countries, although the rate of increase is lower than when the epidemic first started. The epidemiology of HIV infection in the Caribbean differs from that of most other parts of the world because the mode of spread does not easily fit into any of the three World Health Organization patterns. This review shows that while HIV infection was initially observed among homosexuals and bisexuals, intercourse between heterosexuals has now become the main mode of HIV transmission in the region. This review further finds that HIV infection and AIDS in the Caribbean affects mainly young to middle-aged adults. Infected males outnumber females, but the gap is narrowing, while the Caribbean has no IV drug abuse problem except for in Bermuda and Puerto Rico. The governments of the Caribbean have realized the extent of the problem and have taken measures to try to control the epidemic. The paper considers the history of the epidemic; its epidemiology in terms of sources, prevalence, age, sex, and risk behaviors; HIV seroprevalence in populations such as homosexual and bisexual men, female prostitutes, intravenous drug users, blood donors, and antenatal clinics; trends; and geographical factors in Trinidad and Tobago, Bahamas, Puerto Rico, Bermuda, Haiti, Dominican Republic, St. Lucia, Cuba, and Guyana. The authors also note the effectiveness of the draconian Cuban policy in controlling the spread of HIV and AIDS, but stress that its severe nature may also drive cases underground, thus leading to an overall understating of the dimensions of the AIDS epidemic in the country.

Gene therapy for cancer.

Advances in molecular biology and technology now being made will open the way to using gene transfer as a therapeutic option for patients with cancer. Since there are > 5,000 known genetic diseases, the potential impact of these techniques is enormous. Possibilities for the application of gene therapy are emerging and along with them complex safety, ethical, and financial issues that will require resolution. Many of these concerns will become relevant to the oncology nurse, who will need to understand the science, ethics, safety considerations, and impact of this experimental therapy on the patient. Since gene therapy is a rapidly evolving method of treatment, it will be a challenge to remain up to date and knowledgeable.